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ELECTRONICALLY FILED - 2020 November 10 4:17 PM - SCPSC - Docket # 2020-125-E - Page 1 of 100 EXHIBIT 2

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EXHIBIT 2

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 1 of 22

A SCANA COMPANY

Generator Interconnection System Impact Studyfor

SCE&G V.C. Summer Nuclear ¹2

Prepared for:SCE&G Nuclear Group

July 5, 2007

Prepared by:SCE&G Transmission Planning

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 2 of 22

TABLE OF CONTENTS

General Discussion..

I. Generator Information.

... Page 3

. Page 5

II. Transmission Studiesa. Power Flow Analysisb. Short Circuit Analysis .

c. Stability Analysis

... Page 5

... Page 5

... Page 6

... Page 6

III. Required Interconnection Facilities. ... Page 17

IV. Engineering Design & Cost.a. Engineering Single Line Layout ..

b. Transmission & Substation Cost.

Page 19... Page 19

..... Page 21

V. Adjustments to the VC Summer ¹2 Interconnection Plan ....... Page 22

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 3 of 22

Generator Interconnection System Impact Studyfor

SCE&G V.C. Summer Nuclear ¹2

A Generator Interconnection System Impact Study is an extension of the previousGeneration Interconnection Feasibility Study, and is a detailed study of the SCE8Gtransmission system considering the full output of the proposed new generation. TheSystem Impact Study includes a full test of the NERC Reliability Standards Table 1 andthe SCE&G Internal Transmission Planning Criteria.

General Discussion

The SCE&G Nuclear Group has applied for interconnection of a new 1375 MVA nucleargenerator near the existing V.C. Summer site. This new generator would be jointlyowed by SCE8G and Santee Cooper, SCE&G would own 55% and Santee Cooperwould own the remaining 45%. In this study Santee Cooper's portion of the generatoroutput was represented as delivered to the Santee Cooper system.

In addition to this Interconnection System Impact Study, SCE&G Transmission Planningparticipated in a joint study with Southern Company, Santee Cooper, Duke Energy andother interconnected transmission providers to evaluate the effect of this generator andother planned generators in the region. Results of this joint study indicated nounacceptable interaction between these planned generators or the identified associatedtransmission expansion.

In the future, SCE&G Transmission Planning will periodically review the results of thisInterconnection System Impact Study to determine if the recommended expansionremains valid.

The previously completed Feasibility Study recommended the following transmissionline improvements:

1. Construct a VC Summer ¹2-Killian 230kV line with 81272 conductor~ (add 230kV terminal at Killian)

2. Construct a VC Summer ¹2-Lake Murray 230kV line with 81272 conductor~ (add 230kV terminal at Lake Murray)

3. Construct a VC Summer ¹2-VC Summer (existing) Bus ¹2 230kV line with 81272conductor

~ (add 230kV terminal at VC Summer ¹1 Bus ¹2)4. Construct a VC Summer ¹2-VC Summer (existing) Bus ¹3 230kV line with 81272

conductor~ (add 230kV terminal at VC Summer ¹1 Bus ¹3)

5. Upgrade the existing Denny Terrace-Lyles 230kV line to 812726. Upgrade the existing Parr-VC Summer ¹1 230kV line to 812727. Upgrade the existing Parr-VC Summer ¹2 230kV line to 812728. Add a 3rd 230/115kV 336 MVA auto transformer at Lake Murray9. Add a 3rd 230/115kV 336 MVA auto transformer at Denny Terrace

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 4 of 22

10. Upgrade the existing Saluda-McMeekin 115kV line to B127211. Upgrade the existing Lake Murray-McMeekin 115kV line to B127212. Upgrade the existing Lake Murray-Saluda 115kV to with B1272

In addition, it will be necessary to construct a new 230kV generator substation at theproposed site using a breaker-and-a-half design with seven 230kV terminals.

1. One -for the generator step up transformer2. One — for station service3. One - for the new 230kV line to the existing V. C. Summer 230kV bus ¹24. One-for the new 230kV line to the existing V. C. Summer 230kV bus ¹35. One — for the new 230kV line to Lake Murray6. One-for the new 230kV line to Killian7. One-for the new 230kV line to Santee Cooper

A total of eleven 230kV breakers are needed at the new generator substation for thisdesign.

To resolve overstressed conditions of several 230kV and 115kV breakers as describedin the Short Circuit Analysis section, Transmission Planning recommends replacing thefollowing breakers with higher interrupting capability breakers:

Location Volta e areaker ttVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC Summer

230230230230230230230230230230230

87228732874287728792883288428852889289128942

ParrParrParrParrParr

230 6402230 6412230 6422230 6432230 6442

Saluda H dro 115 562McMeekinMcMeekinEdenwoodEdenwoodEdenwood

115 1051115 2051115 2712115 3672115 3682

Denny Terrace 115 8032Denny Tenace 115 8042Denn Terrace 115 8092

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 5 of 22

The report will be presented as follows:

I. Generation Informationll. Transmission Studies

A. Power Flow AnalysisB. Short Circuit AnalysisC. Stability Analysis

ill. Required Interconnection FacilitiesIV. Engineering Design 6 Cost

I. Generator Information

The generator design consists of a single nuclear unit and one step-up transformer.The generator unit will have a maximum gross MVA output capacity of 1,375 MVA anda maximum continuous net MW of 1,165 MW.

The generator design consists ofMVA — gross:MW — net:Power Factor:Voltage:Speed:X'd-sat.: 0.465 PU;X2-sat.: 0.320 PU;

the following information:13751165between .90 and 1.0522I&V

1800 rpmX"d-sat.: 0.325 PUXO: 0.237 PU

II. Transmission Studies

A. Power Flow Analysis

Since the completion of the Generation Interconnection Feasibility Study,modifications were made to the 230kV generator substation layout and thearrangement of lines connecting to the existing V.C. Summer substation and theproposed V.C. Summer substation. These changes resulted in the proposedretirement of the Parr 230kV substation. The original improvements along withthese proposed modifications were modeled and Transmission Planning has runmore detailed power flow analysis of the SCESG transmission system to include afull test of the NERC Reliability Standards Table 1 and the SCEKG InternalTransmission Planning Criteria. This analysis shows the following overloadcondition due to the additional generation:

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 6 of 22

Transmission Planning recommends that this contingency event be mitigated byinstalling a 2" bus tie breaker at the Denny Terrace 230kV bus.

B. Short Circuit Analysis

The previously complete feasibility study indicated sixteen 230kV breakers and nine115kV breakers were overstressed due to the additional generation at V. C. Summerand must be replaced. However, five of these 230kV breakers are at Parr 230kVsubstation and because of the proposed retirement of the Parr 230kV substation,these five breaker replacements are no longer required. Additionally, two 230kVbreakers are eliminated at the VC Summer ¹1 Substation with the new linearrangement. Transmission Planning now recommends that nine 230kV breakersand nine 115kV breakers be replaced as listed in the recommendations section ofthis report.

C. Stability Analysis

1. Overview of Stability Analysis.The stability study of the connection of the V.C. Summer ¹2 AP1000 generator tothe SCE&G and SCPSA transmission systems assessed the ability of this generatorto remain in synchronism following selected transmission system contingencies.Also reviewed were the adequacy of damping of generation/transmission oscillationsand the impact of the proposed generator on the stability performance of othersystem generators. System voltage responses were examined for indications ofvoltage instability. In addition, generator frequency responses and the effects ofprotective system performance were evaluated.

For the system peak load cases, the nearby V.C. Summer ¹1 generator wassimulated as switched off except for where noted as otherwise. In addition, the230kV transmission line connecting the V.C. Summer ¹2 generator switchyard toSCPSA's Pomaria substation was switched out. These outages were simulated inorder to account for the possibility that major generation and transmission could beout of service during the operation of the connecting facility. Power flow studiesshowed that these were the generation and transmission outages that resulted in thegreatest impact on the reactive output of the V.C. Summer ¹2 generator.

Rotor angle responses of the V.C. Summer ¹2 generator were simulated in order todetermine if angular instability could result from likely contingencies. Generatorfrequency deviations were examined in order to determine if generator frequencyprotection could result in generator tripping. The results of the loss of the V.C.

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 7 of 22

Summer ¹2 generator were examined in order to determine if any resultingunderirequency relay operations would lead to system load shedding. Finally, theeffects of each contingency on the V.C. Summer ¹2 230kV switchyard bus wereexamined along with voltages at the existing V.C. Summer ¹1 230kV and 115kVOffsite Power Supply buses to determine if the voltage requirements of the OffsitePower Supply buses were violated. Generator response plots are not included butare available for review upon request.

An initial 30 second steady state simulation for the selected connection configurationwas performed in order to establish that steady state conditions existed prior to faultconditions. The simulation of each contingency repeated the steady state conditionfor 1 second prior to introducing permanent fault conditions so that the responsescould be compared to the initial steady state condition. In order to determine theeffects on all system generators, contingencies were simulated under system peakload conditions and system valley load conditions.

Contingencies were selected in order to satisfy each of four categories as specifiedby NERC Reliability Standards TPL-001 through TPL-004. As a companion to thisstudy, SCPSA has performed a study of this generator interconnection and hasdetermined that the NERC Reliability Standards are satisfied for its system. AnExecutive Summary of the SCPSA study of generator rotor angle responses tocontingencies on its system follows the results of the SCE8G stability anaiysis.Although not included in this report, a stability study of this interconnection was alsoperformed for the VCS ¹2 8 VCS ¹3 Combined Operating License Application(COLA). The results of that study support the findings of this Interconnection Study.

The results of the stability analysis are described in the following sections and aresummarized following the detailed results.

2. Results of Peak Load Stability Analysis.A.1. Steady state conditions (NERC Category A condition)

The interconnection of the V.C. Summer ¹2 generator was shown to result in systemsteady state conditions. Generator rotor angles and frequencies showed nodeviations through out the 30 second simulation. The voltage at the V.C. Summer¹2 bus remained at 232.3kV during the simulation. The voltages at the V.C.Summer ¹1 Offsite Power Supply buses were constant at 232.3kV and 117.75kV.

A.2. Normal clearing of a three phase fault on the V.C. Summer ¹2 generatorterminal 26kV bus (NERO Category B-1 Contingency)

Following a 1 second steady state period, a permanent fault was simulated at the26Kv side of the V.C. Summer ¹2 generator step up transformer. This results in theopening of the generator breaker 5 cycles after the appearance of the fault. Sincethe station service buses are normally served from the 26kV bus, this operationwould result in the loss of the station service loads. However, the station fasttransfer scheme switches these loads to the switchyard 230kV bus and allows thecontinued service of these loads.

Rotor angle oscillations were moderate and well damped with no indication ofangular instability. There was no indication of voltage instability. Likewise, system

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 8 of 22

frequency responses were also moderate and well damped with no indication ofsystem underfrequency load shedding or generator under/overfrequency operations.

During the application of the fault, the voltage at the V.C. Summer ¹2 bus dropped to121.41kV. The V.C. Summer ¹1 230kV and 115kV Offsite Power Supply busvoltages dropped to 125.06kV and 78.98kV respectively. This allowed the degradedvoltage and loss of voltage relay timers to initiate. However, the voltages recoveredenough to reset the timers within 1 cycle of the clearing of the fault.

Steady state conditions were reestablished with no further system operations.

A.3. Delayed clearing of a single line to ground fault on the future V.C. Summer ¹2switchyard to the existing V.C. Summer ¹1 generator switchyard bus ¹2 (NERCCategory C-8 contingency)

Since this contingency places a fault near the existing V.C. Summer ¹1 generator,this unit was modeled as switched on. All local transmission lines were alsomodeled as in service. Following a 1 second steady state period, a permanentsingle phase-to-ground fault was simulated at the V.C. Summer ¹2 end of the V.C.Summer ¹2 — V.C. Summer «1 230kV transmission line ¹2. The circuit breaker atthe V.C. Summer ¹1 end of the line was simulated as operating normally. Thebreaker and a half scheme at the V.C. Summer ¹2 switchyard cleared the faultfollowing a fault duration of approximately 0.25 seconds.

During the application of the fault, the voltage at the V.C. Summer ¹2 bus dropped to121.44kV. The V.C. Summer ¹1 230kV and 115kV Offsite Power Supply busvoltages dropped to 126.94kV and 71.20kV respectively. This allowed the degradedvoltage and loss of voltage relay timers to initiate. However, the voltages recoveredenough to reset the timers within 1 cycle of the clearing of the fault.

Rotor angle osciilations were moderate and were adequately damped with noindication of angular instability. There was no indication of voltage instability.Likewise, system frequency responses were also moderate and adequately dampedwith no indication of system underfrequency load shedding or generatorunder/overfrequency operations.

Steady state conditions were reestablished with no further system operations.

A.4. Normal clearing of a three phase fault on the existing V.C. Summer ¹1generator switchyard bus ¹1 (NERO Category D-10 contingency)

Since this contingency places a fault near the existing V.C. Summer ¹1 generator,this unit was modeled as switched on. All local transmission lines were alsomodeled as in service. Following a 1 second steady state period, a permanentsingle three phase fault was simulated at the V.C. Summer ¹1 bus ¹1. Since this isthe bus that the V.C. Summer ¹1 generator is connected to that generator wastripped when the fault was cleared. In addition, in order to prevent the FairfieldPumped Storage generators from becoming unstable, a Special Protection Systemwill need to be installed at the V.C. Summer ¹1 switchyard that will trip those units

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 9 of 22

as well. The operations to clear the fault and trip the generators will occur within 6cycles from the appearance of the bus fault.

During the application of the fault, the voltage at the V.C. Summer ¹2 230kV busdropped to 6.99kV. The V.C. Summer ¹1 230kV and 115kV Offsite Power Supplybus voltages dropped to 0.00kV and 21.79kV respectively. This allowed thedegraded voltage and loss of voltage relay timers to initiate. However, the voltagesrecovered enough to reset the timers within 14-15 cycles following the appearanceof the fault.

Rotor angle oscillations were moderate and were adequately damped with noindication of angular instability. There was no indication of voltage instability.Likewise, system frequency responses were also moderate and adequately dampedwith no indication of system underfrequency load shedding or generatorunder/overfrequency operations.

Steady state conditions were reestablished with no further system operations.

3. Results of Low Load Stability Analysis.A.1. Steady state conditions (NERC Category A condition)

The interconnection of the V.C. Summer ¹2 generator was shown to result in systemsteady state conditions. Generator rotor angles and frequencies showed nodeviations through out the 30 second simulation. The voltage at the V.C. Summer¹2 bus remained at 232.3kV during the simulation. The voltages at the V.C.Summer ¹1 Ofl'site Power Supply buses were constant at 232.3kV and 116.84kV.

A.2. Normal clearing of a three phase fault on the V.C. Summer ¹2 generatorterminal 26kV bus (NERC Category B-1 Contingency)

Following a 1 second steady state period, a permanent fault was simulated at the26Kv side of the V.C. Summer ¹2 generator step up transformer. This results in theopening of the generator breaker 5 cycles after the appearance of the fault. Sincethe station service buses are normally served from the 26kV bus, this operationwould result in the loss of the station service loads. However, the station fasttransfer scheme switches these loads to the switchyard 230kV bus and allows thecontinued service of these loads.

Rotor angle oscillations were small but poorly damped due to the smaller level ofsynchronizing torque within the system due to the reduced amount of generation online during system low load conditions. However, the generator rotor angleoscillations were eventually damped and there was no indication of angularinstability. There was no indication of voltage instability. Likewise, systemfrequency responses were also small and poorly damped but with no indication ofsystem underfrequency load shedding or generator under/overfrequency operations.

During the application of the fault, the voltage at the V.C. Summer ¹2 bus dropped to133.47kV. The V.C. Summer ¹1 230kV and 115kV Offsite Power Supply busvoltages dropped to 136.00kV and 74.82kV respectively. This allowed the degraded

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 10 of 22

voltage and loss of voltage relay timers to initiate. However, the voltages recoveredenough to reset the timers within 1 cycle of the clearing of the fault.

Steady state conditions were reestablished with no further system operations.

A.3. Delayed clearing of a single line to ground fault on the future V.C. Summer¹2 switchyard to the existing V.C. Summer ¹1 generator switchyard bus ¹2 (NERCCategory C-8 contingency)

Since this contingency places a fault near the existing V.C. Summer ¹1 generator,this unit was modeled as switched on. All local transmission lines were alsomodeled as in service. Following a 1 second steady state period, a permanentsingle phase-to-ground fault was simulated at the V.C. Summer ¹2 end of the V.C.Summer ¹2 — V.C. Summer ¹1 230kV transmission line ¹2. The circuit breaker atthe V.C. Summer ¹1 end of the line was simulated as operating normally. Thebreaker and a half scheme at the V.C. Summer ¹2 switchyard cleared the faultfollowing a fault duration of approximately 0.25 seconds.

During the application of the fault, the voltage at the V.C. Summer ¹2 bus dropped to115.83kV. The V.C. Summer ¹1 230kV and 115kV Offsite Power Supply busvoltages dropped to 121.03kV and 67.65kV respectively. This allowed the degradedvoltage and loss of voltage relay timers to initiate. The voltages recovered enoughto reset the timers within 2-3 cycles of the clearing of the fault.

Rotor angle oscillations were small and were adequately damped with no indicationof angular instability. There was no indication of voltage instability. Likewise,system frequency responses were also small and adequately damped with noindication of system underfrequency load shedding or generatorunder/overfrequency operations.

Steady state conditions were reestablished with no further system operations.

A.4. Normal clearing of a three phase fault on the existing V.C. Summer ¹1generator switchyard bus ¹1 (NERC Category D-10 contingency)

Since this contingency places a fault near the existing V.C. Summer ¹1 generator,this unit was modeled as switched on. All local transmission lines were alsomodeled as in service. Following a 1 second steady state period, a permanent threephase fault was simulated at the V.C. Summer ¹1 bus ¹1. Since this is the bus thatthe V.C. Summer ¹1 generator is connected to, that generator was tripped when thefault was cleared. In addition, in order to prevent the Fairfield Pumped Storagegenerators from becoming unstable, a Special Protection System will need to beinstalled at the V.C. Summer ¹1 switchyard that will trip those units as well. Theoperations to clear the fault and trip the generators will occur within 6 cycles from theappearance of the bus fault.

During the application of the fault, the voltage at the V.C. Summer ¹2 230kV busdropped to 5.89kV. The V.C. Summer ¹1 230kV and 115kV Offsite Power Supplybus voltages dropped to 0.00kV and 18.19kV respectively. This allowed thedegraded voltage and loss of voltage relay timers to initiate. However, the voltages

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 11 of 22

recovered enough to reset the timers within 12-17 cycles of the appearance of thefault.

Rotor angle oscillations were moderate and were adequately damped with noindication of angular instability. There was no indication of voltage instability.Likewise, system frequency responses were also moderate and adequately dampedwith no indication of system underfrequency load shedding or generatorunder/overfrequency operations.

Steady state conditions were reestablished with no further system operations. Theplots for this case are shown in

A.5. Three phase fault with normal clearing on the existing V.C. Summer ¹1generator bus ¹2 to Fairfield Pumped Storage Generators ¹ 5-8 (NERC Category D-11 contingency)

Since this contingency places a fault near the existing V.C. Summer ¹1 generator,this unit was modeled as switched on. All local transmission lines were alsomodeled as in service. Following a 1 second steady state period, a permanentthree phase fault was simulated on the 230kV transmission line that connects theV.C. Summer ¹1 bus ¹2 to the Fairfield Pumped Storage units ¹5-8. When this linewas openod these units which were operating in the pumping mode were taken offline. This represents the largest load that can be removed from the system as aresult of a single event.

During the application of the fault, the voltage at the V.C. Summer ¹2 230kV busdropped to 6.00kV. The V.C. Summer ¹1 230kV and 115kV Offsite Power Supplybus voltages dropped to 0.00kV and 18.40kV respectively. This allowed thedegraded voltage and loss of voltage relay timers to initiate. The voltage recoverydiffered between the 230kV and 115kV Offsite Power Supply buses but was easilysufficient to allow all relay timers to reset to prevent the switching of the EngineeredSafeguard Features buses from the Offsite Power Supply buses.

Rotor angle oscillations were moderate and were adequately damped with noindication of angular instability. Likewise, system frequency responses were alsomoderate and adequately damped with no indication of system underfrequency loadshedding or generator under/overfrequency operations.

Steady state conditions were reestablished with no further system operations.

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 12 of 22

V.C. Summer ¹2 STABILITY STUDY RESULTSPeak S stem Load Cases

A.1. Stead state conditionsA. Generator rotor angles demonstrate steady state condition.B. There was no indication of voltage instability.C. Generator frequencies show no deviation.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-001 compliance demonstrated.

A.2. Three phase fault with normal clearing on the V.C. Summer ¹2 generatorterminal 26kV bus

A. Moderate rotor angle oscillation for SCE&G generators with good dampingand no indication of instability.

B. There was no indication of voltage instability.C. Generator frequency responses are moderate and well damped with no

system UFLS or generator under/over frequency operations.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-002 compliance demonstrated.

A.3. Single line to ground fault with delayed clearing on the future V.C. Summer ¹2switchyard to the existing V.C. Summer ¹1 generator switchyard bus ¹2

A. Moderate rotor angle oscillation for SCE8G generators with good dampingand no system instability.

B. There was no indication of voltage instability.C. Generator frequency responses are moderate and well damped with no

system UFLS or generator under/over frequency operations.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-003 compliance demonstrated.

A.4. Three phase fault with normal clearing on the existing V.C. Summer ¹1generator bus ¹1

A. Moderate rotor angle oscillation for SCE&G generators with adequatedamping, but Special Protection Scheme to trip Fairfield Pumped Storagegenerators is needed.

B. There was no indication of voltage instability.C. Generator frequency responses are moderate and well damped with no

system UFLS or generator under/over frequency operations.D. Special Protection System to trip Fairfield Pumped Storage ¹1-8 required.E. No negative impact on existing V.C. Summer ¹1 offsite power.F. NERC Reliability Standard TPL-004 compliance demonstrated.

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 13 of 22

V.C. Summer ¹2 STABILITY STUDY RESULTSS stem Low Load Cases

A.1. Stead state conditionsA. Generator rotor angles demonstrate steady state condition.B. There was no indication of voltage instability.C. Generator frequencies show no deviation.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-001 compliance demonstrated.

A.2. Three phase fault with normal clearing on the V.C. Summer ¹2 generatorterminal 26kV bus

A. Small rotor angle oscillation for SCE&G generators with poor but adequatedamping.

B. There was no indication of voltage instability.C. Generator frequency oscillations small with poor but adequate damping.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-002 compliance demonstrated.

A.3. Single line to ground fault with delayed clearing on the future V.C. Summer ¹2switchyard to the existing V.C. Summer ¹1 generator switchyard bus ¹2

A. Small rotor angle oscillation for SCE&G generators with adequate damping.B. There was no indication of voltage instability.C. Generator frequency oscillations also small with adequate damping.D. NERC Reliability Standard TPL-003 compliance demonstrated.

A.4. Three phase fault with normal clearing on the existing V.C. Summer ¹1generator bus ¹1

A. Moderate rotor angle oscillation for SCE&G generators with adequatedamping.

B. There was no indication of voltage instability.C. Generator frequency oscillations moderate and adequately damped.D. Special Protection System to trip Fairfield Pumped Storage ¹1-8 required.E. No negative impact on existing V.C. Summer ¹1 offsite power.F. NERC Reliability Standard TPL-004 compliance demonstrated.

A.5. Three phase fault with normal clearing on the existing V.C. Summer ¹1generator bus ¹2 to Fairfield Pumped Storage Generators ¹5-8

A. Moderate rotor angle oscillation for SCE&G generators with adequatedamping.

B. There was no indication of voltage instability.C. Generator frequency oscillations moderate and adequately damped.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-004 compliance demonstrated.

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3. SCPSA Executive Summary

Exhibit Q-1 (Exhibit No. (HCY-1))Page 14 of 22

Santee Cooper has completed a portion of a joint utility assessment evaluating thedynamic performance of the bulk transmission system performance with the additionof a proposed 1,165 MW generating unit at the existing V.C. Summer site.Assessments are based on Reliability Standards adopted by the North AmericanElectric Reliability Corporation (NERC) used simulated contingency events ofprojected 2015 summer and light-load seasons.

This study assesses both the transient stability and dynamic stability under normaloperation and for selected contingencies simulated within the Santee Cooper electricsystem. The study focuses on selected contingency events addressing each of thefour contingency Categories defined by NERC Reliability Standards TPL-001through TPL-004. Contingencies selected for inclusion in this study focus onassessing the impact of specific, proposed changes in the power system networkconfiguration and operating scenario associated with the proposed 1,165 MWgenerating unit addition at the existing V.C. Summer site.

Study scenario contingencies are applied to dynamic simulation models representingprojected summer peak and light-load system conditions for 2015. These modelswere developed with coordinated input from Santee Cooper, SCE8G, SouthernCompany, Duke and Progress Energy Caroiinas. Since it is impractical to include allpossible contingency scenarios in specific stability assessments, those contingencyscenarios judged most likely to impact the stability of Santee Cooper facilities areincorporated in this evaluation of actual or proposed system changes. Contingencyevents evaluated and assessments of each simulation are detailed in Table 1.Selected plots for each scenario are included for each simulation under projectedsummer peak and light-load conditions.

Review and appraisal of each of the scenarios evaluated do not identify anyperformance issues within the Santee Cooper bulk transmission system resultingfrom the proposed additional generation at the V.C. Summer site. Each of theselected contingency scenarios from Categories A, B and C and D of NERCPlanning Standard TPL-001 through 004, Table 1 indicates that the Santee Coopersystem is expected to comply with the requirements outlined for these contingencycategories in the projected representation of both the 2015 summer and light-loadseasons.

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 15 of 22

Table 1

Contin enc SimulationsScenario

¹NERC

Cate oB-2

C-3

C-5

C-7

D-3

D-4

D-5

Descri tionNewberry 230 kV to Pomaria 230 kVline has a fault next to Newbery 230 kVSwitching 230 kV switching station. Theline is opened and closed under normalbreaker operation causing the fault toclear.Newberry 230 kV to Greenwood County230 kV line has a fault next to Newbery230 kV Switching 230 kV switchingstation. The line is opened undernormal breaker operation causing thefault to clear. This line is not closed. 5seconds later the Newberry 230 kV toPomaria 230 kV line has a fault next toNewbery 230 kV Switching 230 kVswitching station. The line is openedand closed under normal breakero eration causin the fault to clear.Failure of common structure causesboth Greenwood to Hodges 230 kV andGreenwood to Rainey 230 kV lines tohave a single line to ground fault. Bothlines are taking out of service by normalbreaker operation resulting in theclearing of the fault.

A single line to ground fault on theCamden to Lugoff 230kv occurs nearthe Camden switching station. Due toslow breaker operation there is a delayin clearing the fault. The Camden toLugoff 230 kV line is opening and thenclosed resultin in clearin the fault.Fault on line near Newberry 230 kVstation is not cleared due to breakerfailure. The station is then drop bysecondary breaker protection.

Fault occurs on Pomaria 230 kV buss tiebreaker resulting is delayed clearing of230 kV lines and loss of Pomaria bus.Fault on Blythewood 230 to 69 kVtransformer results in opening andclosing of both VC Summer toBlythewood 230 kV and Blythewood toLugoff 230k kV lines. Both Blythewood230 to 69 kV transformers are trippedresulting in loss of 230 kV support to theSantee Coo er 69kV s stem.

Findin sBoth seasonal case scenarios exhibitgood damping following thedisturbance. Machine relative anglesquickly return to pre-disturbancevalues without significant swings.

Both seasonal case scenarios exhibitgood damping following both the 1"and 2" disturbance. Machine relativeangles quickly return to pre-disturbance values without significantswings during either of thedisturbances.

Both scenarios exhibit good dampingfollowing the disturbance. Thesummer scenario indicates thatmacnine reiative angles quicklyreturning to pre-disturbance valueswith no significant swings followingthe disturbance. The light-loadscenario shows machine relativeangles quickly finding new steadystates of operation with no significantswin s.Both scenarios exhibit good dampingfollowing the disturbance. Themachine relative angles quickly returnto pre-disturbance values nosignificant swings.

Machine relative angles exhibit widerswings than those identified for thesummer season, though bothseasonal scenarios exhibit gooddam in followin the disturbance.Results indicate that oscillationsfollowing the disturbance are well-dam ed for both seasonal scenarios.Both scenarios exhibit good dampingfollowing the disturbance. Themachine relative angles quickly returnto pre-disturbance values nosignificant swings.

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4. Stability Study Conclusions

Exhibit Q-1 (Exhibit No. (HCY-1))Page 16 of 22

This study demonstrates that the proposed V.C. Summer ¹2 generatorinterconnection to the SCEBG and SCPSA systems is compliant with NERCReliability Standards. There was no indication of voltage instability. None ofthe simulations indicated that system UFLS or generator under/overfrequencyoperations would occur. Neither does the interconnection have a negativeimpact on the existing V.C. Summer ¹1 offsite power quality. Several caseswith faults located near the V.C. Summer ¹1 and the Fairfield Pumped Storageunits revealed a need for a Special Protection System that will trip the Fairfieldunits to prevent instability. The SCE8G Relay and SCADA Applicationsdepartment has identified the operating features of such a scheme and willneed to make the required system protection improvements.

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 17 of 22

III. Re uired Interconnection Facilities

The analyses performed in this study confirmed the results of the Feasibility Study andshow that constructing two new 230kV lines from the VC Summer site to the ColumbiaArea load center, plus additional transmission improvements described below, arerequired to reliably transmit the 1,165 MW of the proposed VC Summer ¹2 generatorfrom of the VC Summer area to the remainder of the SCE&G system. Also, theanalyses show that constructing two new 230kV lines is less costly and more effectivethan upgrading the numerous existing 230kV transmission facilities that currentlytransmit power from the VC Summer area.

The required transmission improvements:

1. Construct a VC Summer ¹1 bus ¹1 - Killian 230kV line with B1272conductor. (add 230kV terminal at Killian)

2. Construct a VC Summer ¹2 - Lake Murray 230kV line with B1272 conductor.(add 230kV terminal at Lake Murray)

3. Construct a VC Summer ¹2 - VC Summer ¹1 bus ¹2 230kV line with B1272conductor. (add 230kV terminal at VC Summer ¹1 bus ¹2)

4. Construct a VC Summer ¹2 - VC Summer ¹1 bus ¹3 230kV line with B1272conductor. (add 230kV terminai at VC Surnrner ¹1 bus ¹3)

5. Upgrade the existing Denny Terrace-Lyles 230kV line to B12726. Add a 3rd 230/115kV 336 MVA auto transformer at Lake Murray7. Add a 3rd 230/115kV 336 MVA auto transformer at Denny Terrace8. Upgrade the existing Saluda-McMeekin 115kV line to B12729. Upgrade the existing Lake Murray-McMeekin 115kV line to B127210. Upgrade the existing Lake Murray-Saluda 115kV to with B127211. Add a second 230kV bus tie breaker at Denny Terrace

Construct a new 230kV generator substation at the proposed site using a breaker-and-a-half design with ten 230kV terminals. To minimize the number of line crossings and toretire the Parr 230kV substation, several existing lines are being re-terminated at the VCSummer ¹2 substation and some of the new required lines are terminating at the VCSummer ¹1 substation.

1. VC Summer ¹2 generator step up transformer2. VC Summer ¹2 station service3. New 230kV line to VC Summer ¹1 bus ¹24. New 230kV line to VC Summer ¹1 bus ¹35. New 230kV line to Lake Murray6. Re-terminate existing 230kV line to Lake Murray7. Re-terminate existing 230kV line to Bush River (Duke)8. Re-terminate existing 230kV line to Graniteville9. Re-terminate existing 230kV line to Denny Terrace10. Re-terminate existing 230kV line to Newberry (Santee)

A total of eighteen 230kV breakers are needed at the new generator substation for thisdesign.

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 18 of 22

To resolve overstressed conditions of several 230kV and 115kV breakers as describedin the Short Circuit Analysis section, the following breakers must be replaced withhigher interrupting capability breakers:

Location Volta e 6reaker ¹VC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC Summer

230 8722230 8772230 8792230 8832230 8842230 8852230 8892230 8912230 8942

Saluda H dro 115 562McMeekinMcMeekinEdenwoodEdenwoodEdenwood

115 1051115 2051115 2712115 3672115 3682

Denny Terrace 115 8032Denny Terrace 115 8042Denn Terrace 115 8092

As stated in the stability analysis section, several cases with faults located near the V.C.Summer ¹1 and the Fairlield Pumped Storage units revealed a need for a SpecialProtection System that will trip the Fairfield units to prevent instability. The SCE&GRelay and SCADA Applications department has identified the operating features of sucha scheme and will need to make the required system protection improvements.

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IV. En ineerin Desi n & Cost

Exhibit Q-1 (Exhibit No. (HCY-1))Page 19 of 22

A. Engineering Single line Layout & Substation Arrangement

Transmission Single Line

Duke230 I&

Existing 230 kV lineWinnsboro (Santee)B-1272 ACSR

e to B-1272 ACSR

sboro 230 kV

To Gran230 kv

To Wateree 230 kV

Lake Murray

To Edenwoo

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 20 of 22

Substation Arrangement

Fairfield itl & ¹2

Nuclear ¹1

Wino«bore (Santec)

VVCSl bus ¹1

«Newpo

wood (Santee)

«Bush River (Duke)

«Newberry (Santee)

e re-terminated

Lake Murray ¹

*Lake Murray ¹1

«Denny Terrace ¹1

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B. Transmission & Substation Cost

Exhibit Q-1 (Exhibit No. (HCY-1))Page 21 of 22

All cost estimates are in 2006 dollars.

1. Construct VC Summer-Killian 230kV.. 25,000,000~ (add 230kV terminal at Killian). ..600,000

2. Construct VC Summer-Lake Murray 230kV. 17,000,000~ (add 230kV terminal at Lake Murray) ......................................600,000

3. Construct VC Summer ¹2-VC Summer ¹1 bus ¹2 ..................................600,000~ (add 230kV terminal at VC Summer ¹1 bus ¹2) ......................600,000

4. Construct VC Summer ¹2-VC Summer ¹1 bus ¹3 ..................................600,000~ (add 230kV terminal at VC Summer ¹1 bus ¹3) ......................600,000

5. Upgrade existing Denny Terrace-Lyles 230kV .....................................1,500,0006. Add a 3rd 230/115kV 336 MVA auto transformer at Lake Murray ........5,000,0007. Add a 3rd 230/115kV 336 MVA auto transformer at Denny Terrace ....8,000,0008. Upgrade existing Saluda-McMeekin 115kV line 125,0009. Upgrade existing Lake Murray-McMeekin 115kV line..............................500,00010. Upgrade existing Lake Murray-Saluda 115kV .450,00011. Add second 230kV bus tie breaker at Denny Terrace .............................500,000

Construct a new 230kV generator substation at the proposed site using a breaker-and-a-half design with ten 230kV terminals. 12,589,000

Construct Transmission from VC Summer ¹2 Generator to VC Summer ¹2Switchyard. .340,000

Re-terminate VC Summer area lines to the VC Summer ¹2 Substation .........1,271,000

1. Re-terminate Bush River (Duke) 230kV line to VC Summer ¹2 substation2. Re- terminate Newberry (SCPSA) 230kV line to VC Summer ¹2 substation (paid

by SCPSA)3. Re-terminate Ward 230kV line to VC Summer ¹2 substation4. Re-terminate Lake Murray 230kV ¹1 line to VC Summer ¹2 substation5. Re-terminate Denny Terrace 230kV ¹1 line to VC Summer ¹2 substation

Re-terminate VC Summer area lines to the VC Summer ¹1 Substation ............681,000

1. Re-terminate Blythewood (SCPSA) 230kV line to VCS bus ¹1 (paid by SCPSA)2. Re-terminate Pineland 230kV line to VCS bus ¹33. Re-terminate Denny Terrace 230kV line ¹2 to VCS bus ¹34. Re-terminate Newport (Duke) 230kV line to VCS bus ¹2

Replace overstressed1. 230kV breakers-9.2. 115kV breakers - 9.

....4,500,0002,700,000

Total Cost Estimate.. ..... $83,756,000

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Exhibit Q-1 (Exhibit No. (HCY-1))Page 22 of 22

V. Ad'ustments to the VC Summer ¹2 Interconnection Plan

SCE8G Transmission Planning is adjusting the VC Summer ¹2 generatorinterconnection plan to consider future native load needs of the system. Theexisting system has limited capability to serve future load growth along the Interstate77 corridor. Without reactive compensation, the system can serve only an additional40 MW of customer load. With reactive compensation, 81 MW can be served.

Transmission Planning is expecting the load along 1-77 to grow rapidly in the future,exceed the additional 81 MW amount and, at that time, the area will need additionaltransmission expansion to reliably serve the growing load.

Transmission Planning is recommending that the VC Summer — Killian 230kVtransmission line, discussed above in this report, be routed from VC Summer toWinnsboro and then to Killian. This will extend the 230kV line but with relatively littleadditional cost this will also provide for service along the 1-77 corridor for many yearsinto the future.

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 1 of 22

A SCANA COAfPANV

Generator Interconnection System Impact Studyfor

SCE&G V.C. Summer Nuclear ¹3

Prepared for:SCE&G Nuclear Group

August 31, 2007

Prepared by:SCE&G Transmission Planning

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 2 of 22

TABLE OF CONTENTS

General Discussion.

I. Generator Information.

.. Page 3

Page 5

II. Transmission Studies.a. Power Flow Analysisb. Short Circuit Analysis.c. Stability Analysis

... Page 5

... Page 5Page 7Page 7

III. Required Interconnection Facilities. Page 17

IV. Engineering Design 8 Cost.a. Engineering Single Line Layout......b. Transmission 8 Substation Cost.....

Page 19..... Page 19..... Page 22

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 3 of 22

Generator Interconnection System Impact Studyfor

SCES G V.C. Summer Nuclear ¹3

A Generator Interconnection System Impact Study is an extension of the previousGeneration Interconnection Feasibility Study, and is a detailed study of the SCE&Gtransmission system considering the full output of the proposed new generation. TheSystem Impact Study includes a full test of the NERC Reliability Standards Table 1 andthe SCE&G Internal Transmission Planning Criteria.

General Discussion

The SCE&G Nuclear Group has applied for interconnection of an additional 1375 MVAnuclear generator near the existing V.C. Summer site. This new generator would bejointly owed by SCE8G and Santee Cooper, SCE&G would own 55% and SanteeCooper would own the remaining 45%. In this study Santee Cooper's portion of thegenerator output was represented as delivered to the Santee Cooper system.

In the future, SCE&G Transmission Plannina will periodically review the results of thisInterconnection System Impact Study to determine if the recommended expansionremains valid.

The previously completed Feasibility Study recommended the following transmissionline improvements:

1. Construct VCS New-St George 230kV Double Circuit B1272 line (135 miles)(Add two 230kV terminals at VC Summer New using breaker-and-a-half design)

2. Construct VCS New-VCS¹1, Bus ¹1 230kV line(Add one 230kV terminal at existing VC Summer Bus ¹1)(Add one 230kV terminal at VC Summer New using breaker-and-a-half design)

3. Establish a St George 230kV Switching Station using breaker-and-a-half design(6 terminals - 9 breakers)(Add land)

4. Fold-in the Canadys-Santee 230kV line at St George 230kV

5. Upgrade the Canadys-St George 230kV line to B1272(Upgrade Canadys terminal)

6. Fold-in the Wateree-Summerville 230kV line at St George 230kV

7. Upgrade the St George-Summerville 230kV line to B1272

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 4 of 22

(Upgrade Summerville terminal)

8. Upgrade Saluda-Georgia Pacific 115kV Double Circuit line to 1272(Upgrade Saluda terminal)

Add five (5) terminals (9 breakers) to the VC Summer New substation using breaker-and-a-half design.

1. One-for VC Summer ¹3 generator step up transformer2. One - for VC Summer ¹3 station service3. One - for the new 230kV line to the existing VC Summer ¹1 230kV bus ¹14. Two — for the 2 new 230kV lines to St George

To resolve overstressed conditions of the breakers as described in the Short CircuitAnalysis section, Transmission Planning recommends replacing the following breakerswith higher interrupting capability breakers:

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 5 of 22

I. Generator Information

The generator design consists of a single nuclear unit and one step-up transformer.The generator unit will have a maximum gross MVA output capacity of 1,375 MVA anda maximum continuous net MW of 1,165 MW.

The generator design consists of the following information:MVA — gross: 1375MW- net: 1165Power Factor: between .90 and 1.05Voltage: 26kvSpeed: 1800 rpmX'd-sat.: 0.397 PU; X"d-sat.: 0.261 PUX2-sat.: 0.261 PU; XO: 0.176 PU

II. Transmission Studies

A. Power Flow Ana!ysis

Since the completion of the Generation Interconnection Feasibility Study,modifications were made to the 230kV generator substation layout and thearrangement of lines connecting to the existing V.C. Summer substation and theproposed V.C. Summer substation. These changes resulted in the proposedretirement of the Parr 230kV substation. The original improvements along withthese proposed modifications were modeled and Transmission Planning has runmore detailed power flow analysis of the SCE&G transmission system to include afull test of the NERC Reliability Standards Table 1 and the SCE&G InternalTransmission Planning Criteria.

Three different projected loading conditions were simulated for the 2019 time period:Summer Peak Load, Shoulder Load (75'/o of peak) and Light Load (38'/o of peak).

For the Summer Peak Load and Shoulder Load simulations, the analysis identifiedno additional overload conditions due to the additional generation that had notalready been previously identified in the Feasibility Study. However, for the LightLoad simulation, the following new conditions occurred:

In the basecase, with no outages, the VC Summer-Newport (Duke) 230kV line loadsto 98'/o of its continuous rating of 437 MVA.

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Exhibit Q-2 (Exhibit No (HCY-2))Page 6 of 22

The n-2 analyses show the following overload conditions due to the additionalgeneration:

Overloaded Facitit

VC Summer ¹1 bus ¹2-NewportDuke 230kV line

VC Summer ¹1 bus ¹2-NewportDuke 230kV line

VC Summer ¹1 bus ¹2-NewportDuke 230kV line

VC Summer ¹1 bus ¹2-NewportDuke 230kV line

VC Summer ¹1 bus ¹2-NewportDuke 230kV line

VC Summer ¹1 bus ¹2-NewportDuke 230kV line

Rating LoadingMVA

456 104

456 104

456 103

456 103

456 101

456 101

Contin enc sVC Summer ¹1 bus ¹1-Winnsboro(Santee Cooper) 230kV line andVC Summer ¹1 bus ¹1-BlythewoodSantee Coo er 230kV line

VC Summer New-Pomaria (SanteeCooper) 230kV line ¹1 and VCSummer New-Pomaria (SanteeCoo er 230kV line ¹2VC Summer New-Bush River(Duke) 230kV line and VC Summer¹1 bus ¹1-Blythewood (SanteeCoo er 230kV lineVC Summer New-Bush River(Duke) 230kV line and VC Summer¹1 bus ¹1-Winnsboro (SanteeCoo er 230kV line

VC Summer New-Bush River(Duke) 230kV line and VC SummerNew-Ward 230kV line

VC Summer New-Bush River(Duke) 230kV line and VC SummerNew-St Geor e 230kV line

The installation of a series reactor on the VC Summer ¹1-Newport (Duke) 230kV linewill reduce the current flow on the line and eliminate these conditions.

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 7 of 22

B. Short Circuit Analysis

The previously completed feasibility study indicated three 230kV breakers and eight115kV breakers were overstressed due to the additional generation at V. C. Summerand must be replaced. This analysis identified no overstressed breakers due to theadditional generation that had not already been previously identified in the Feasibilitystudy.

The addition of the VC Summer ¹3 unit will increase the fault current in the VCSummer area to the point where 80kA breakers will be approaching the point ofbecoming overstressed. As the fault current capability of the interconnectedtransmission system increases in the future, this will require breakers with largerinterrupting capability.

C. Stability Analysis

1. Overview of Stability Analysis.The stability study of the connection of the V.C. Summer ¹3 AP1000 generator tothe SCE&G transmission system assessed the ability of this generator to remain insynchronism following selected transmission system contingencies. Also reviewedwere the adequacy of damping of generation/transmission oscillations and theimpact of the proposed generator on the stability performance of other systemgenerators. System voltage responses were examined for indications of voltageinstability. In addition, generator frequency responses and the effects of protectivesystem performance were evaluated.

For the system peak load cases, the adjacent V.C. Summer ¹2 generator wassimulated as switched off except for where noted as otherwise. In addition, the230kV transmission line connecting the V.C. Summer ¹3 generator switchyard toSCE&G'S Denny Terrace substation was switched out. These outages weresimulated in order to account for the possibility that major generation andtransmission could be out of service during the operation of the connecting facility.Power flow studies showed that these were the generation and transmissionoutages that resulted in the greatest impact on the reactive output of the V.C.Summer ¹3 generator.

Rotor angle responses of the V.C. Summer ¹3 generator were simulated in order todetermine if angular instability could result from likely contingencies. Generatorfrequency deviations were examined in order to determine if generator frequencyprotection could result in generator tripping. The results of the loss of the V.C.Summer ¹3 generator were examined in order to determine if any resultingunderfrequency relay operations would lead to system load shedding. Finally, theeffects of each contingency on the V.C. Summer ¹2 & ¹3 230kV switchyard buswere examined along with voltages at the existing V.C. Summer ¹1 230kV and115kV Offsite Power Supply buses to determine if the voltage requirements of theOffsite Power Supply buses were violated. Generator response plots are notincluded but are available for review upon request.

7

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 8 of 22

An initial 30 second steady state simulation for the selected connection configurationwas performed in order to establish that steady state conditions existed prior to faultconditions. The simulation of each contingency repeated the steady state conditionfor 1 second prior to introducing permanent fault conditions so that the responsescould be compared to the initial steady state condition. In order to determine theeffects on all system generators, contingencies were simulated under system peakload conditions and system valley load conditions.

Contingencies were selected in order to satisfy each of four categories as specifiedby NERO Reliability Standards TPL-001 through TPL-004. Although not included in

this report, a stability study of this interconnection was also performed for the VCS¹2 8, VCS ¹3 Combined Operating License Application (COLA). The results of thatstudy support the findings of this Interconnection Study.

The results of the stability analysis are described in the following sections and aresummarized following the detailed results.

2. Results of Peak Load Stability Analysis.A.1. Steady state conditions (NERC Category A condition)

The interconnection of the V.C. Summer ¹3 generator was shown to resultin system steady state conditions. Generator rotor angies and frequenciesshowed no significant deviations through out the 30 second simulation. Thevoltage at the V.C. Summer ¹3 bus remained at 232.38kV duding thesimulation. The voltages at the 230kV and 115kV V.C. Summer ¹1 OffsitePower Supply buses were constant at 232.30kV and 117.65kV.

A.2. Normal clearing of a three phase fault on the V.C. Summer ¹2 generatorterminal 26kV bus (NERO Category B-1 Contingency)

Following a 1 second steady state period, a permanent fault was simulatedat the 26Kv side of the V.C. Summer ¹3 generator step up transformer.This results in the opening of the generator breaker 5 cycles after theappearance of the fault. Since the station service buses are normallyserved from the 26kV bus, this operation would result in the loss of thestation service loads. However, the station fast transfer scheme switchesthese loads to the switchyard 230kV bus and allows the continued service ofthese loads.

Rotor angle oscillations were moderate and well damped with no indicationof angular instability. There was no indication of voltage instability.Likewise, system frequency responses were also moderate and welldamped with no indication of system underfrequency load shedding orgenerator under/overfrequency operations.

During the application of the fault, the voltage at the V.C. Summer ¹3 230Kvbus dropped to 119.42kV. The V.C. Summer ¹1 230kV and 115kV OffsitePower Supply bus voltages dropped to 121.436kV and 77.27kVrespectively. This allowed the degraded voltage and loss of voltage relay

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 9 of 22

timers to initiate. However, the voltages recovered enough to reset thetimers within 1 cycle of the clearing of the fault.

Steady state conditions were reestablished with no further systemoperations.

A.3. Delayed clearing of a single line to ground fault on the future V.C. Summer¹2 & ¹3 switchyard to the existing V.C. Summer ¹1 generator switchyardbus ¹1 (NERC Category C-8 contingency)

Since this contingency places a fault near the existing V.C. Summer ¹1generator and both future VCS ¹2 & ¹3 generators, these units weremodeled as switched on. All local transmission lines were also modeledas in service. Following a 1 second steady state period, a permanentsingle phase-to-ground fault was simulated at the V.C. Summer ¹2 & ¹3end of the V.C. Summer ¹2 & ¹3 — V.C. Summer ¹1 230kV transmissionline ¹1. The circuit breaker at the V.C. Summer ¹1 end of the line wassimulated as operating normally. The breaker and a half scheme at theV.C. Summer ¹2 & ¹3 switchyard cleared the fault following a faultduration of approximately 0.25 seconds.

During the application of the fault, the voltage at the V.C. Summer ¹2 & ¹3bus dropped to 107.12kV. The V.C. Summer ¹1 230kV and 115kV OffsitePower Supply bus voltages dropped to 109.64kV and 62.11kVrespectively. This allowed the degraded voltage and loss of voltage relaytimers to initiate. The voltages did not recover in time to reset the loss ofvoltage relay timers within the required 0.24 seconds of the appearance ofthe fault. Consequently, both the 230kV and the 115kV loss of voltagerelays will operate, resulting in a loss of offsite power and switching of theEngineered Safeguard Features 7.2kV buses to the diesel generators.This operation is not caused by the VCS ¹3 generator since any nearbyfault with delayed clearing will depress the VCS¹1 230kV switchyard andlocal 115kV transmission system voltages for a longer period of time thanthe VCS ¹1 loss of voltage relay timers are set for.

Rotor angle oscillations for local generators were pronounced but wereadequately damped with no indication of angular instability. There was noindication of voltage instability. Likewise, system frequency responseswere also moderate and adequately damped with no indication of systemunderfrequency load shedding or generator under/overfrequencyoperations.

Steady state conditions were reestablished with no further systemoperations.

A.4. Normal clearing of a three phase fault on the existing V.C. Summer ¹1generator switchyard bus ¹1 (NERC Category D-10 contingency)

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Exhibit Q-2 (Exhibit No (HCY-2))Page 10 of 22

Following a 1 second steady state period, a permanent single three phasefault was simulated at the V.C. Summer ¹1 bus ¹1. Since this is the busthat the V.C. Summer ¹1 generator is connected to that generator wastripped when the fault was cleared. In addition, in order to prevent theFairfield Pumped Storage generators from becoming unstable, a SpecialProtection System that was identified as needed when V.C. Summer ¹2goes into service will need to be installed at the V.C. Summer ¹1switchyard in order to trip those units as well. The operations to clear thefault and trip the generators will occur within 6 cycles from the appearanceof the bus fault.

During the application of the fault, the voltage at the V.C. Summer ¹3230kV bus dropped to 5.51kV. The V.C. Summer ¹1 230kV and 115kVOffsite Power Supply bus voltages dropped to 0.00kV and 34.47kVrespectively. This allowed the degraded voltage and loss of voltage relaytimers to initiate. However, the voltages recovered enough to reset thetimers within 9 cycles following the appearance of the fault.

Rotor angle oscillations were moderate and were adequately damped withno indication of angular instability. There was no indication of voltageinstability. Likewise, system frequency responses were also moderateand adequately damped with no indication of system underfrequency loadshedding or generator under/overfrequency operations.

Steady state conditions were reestablished with no further systemoperations.

3. Results of Light Load Stability Analysis.A.1. Steady state conditions (NERC Category A condition)

The interconnection of the V.C. Summer ¹3 generator was shown to resultin system steady state conditions. Generator rotor angles and frequenciesshowed no significant deviations through out the 30 second simulation. Thevoltage at the V.C. Summer ¹3 bus remained at 232.30kV during thesimulation. The voltages at the 230kV and 115kV V.C. Summer ¹1 OffsitePower Supply buses were constant at 232.30kV and 117.88kV.

A.2. Normal clearing of a three phase fault on the V.C. Summer ¹3 generatorterminal 26kV bus (NERC Category B-1 Contingency)

Following a 1 second steady state period, a permanent fault was simulatedat the 26Kv side of the V.C. Summer ¹3 generator step up transformer.This results in the opening of the generator breaker 5 cycles after theappearance of the fault. Since the station service buses are normallyserved from the 26kV bus, this operation would result in the loss of thestation service loads. However, the station fast transfer scheme switchesthese loads to the switchyard 230kV bus and allows the continued service ofthese loads.

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Exhibit Q-2 (Exhibit No (HCY-2))Page 11 of 22

Rotor angle oscillations were small but poorly damped due to the smallerlevel of synchronizing torque within the system due to the reduced amountof generation on line during system low load conditions. However, thegenerator rotor angle oscillations were eventually damped and there was noindication of angular instability. There was no indication of voltageinstability. Likewise, system frequency responses were also small andpoorly damped but with no indication of system underfrequency loadshedding or generator under/overfrequency operations.

During the application of the fault, the voltage at the V.C. Summer ¹3 busdropped to 125.70kV. The V.C. Summer ¹1 230kV and 115kV OffsitePower Supply bus voltages dropped to 127.60kV and 72.95kV respectively.This allowed the degraded voltage and loss of voltage relay timers toinitiate. However, the voltages recovered enough to reset the timers within1 cycle of the clearing of the fault.

Steady state conditions were reestablished with no further systemoperations.

A.3. Delayed clearing of a single line to ground fault on the future V.C. Summer¹2 & ¹3 switchyard to the existing V.C. Summer ¹1 generator switchyardbus ¹2 (NERC Category C-6 contingency)

Following a 1 second steady state period, a permanent single phase-to-ground fault was simulated at the V.C. Summer ¹2 8 ¹3 end of the V.C.Summer ¹2 & ¹3 — V.C. Summer ¹1 230kV transmission line ¹1. The circuitbreaker at the V.C. Summer ¹1 end of the line was simulated as operatingnormally. The breaker and a half scheme at the V.C. Summer ¹2 8 ¹3switchyard cleared the fault following a fault duration of approximately 0.25seconds.

During the application of the fault, the voltage at the V.C. Summer ¹2 8 ¹3bus dropped to 98.93kV. The V.C. Summer ¹1 230kV and 115kV OffsitePower Supply bus voltages dropped to 101.03kV and 60.79kV respectively.This allowed the degraded voltage and loss of voltage relay timers toinitiate. The voltages did not recover in time to reset the loss of voltagerelay timers within the required 0.24 seconds of the appearance of the fault.Consequently, both the 230kV and the 115kV loss of voltage relays willoperate, resulting in a loss of offsite power and switching of the EngineeredSafeguard Features 7.2kV buses to the diesel generators. This operation isnot caused by the VCS ¹3 generator since any nearby fault with delayedclearing will depress the VCS ¹1 230kV switchyard and local 115kVtransmission system voltages for a longer period of time than the VCS ¹1loss of voltage relay timers are set for.

Rotor angle oscillations were large and were poorly damped due to thereduced generation during light load conditions and the resulting reductionin system synchronizing torque. An extended simulation showed that thegenerator rotor angle oscillations were eventually damped and there was noindication of angular instability. There was no indication of voltage

11

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Exhibit Q-2 (Exhibit No (HCY-2))Page 12 of 22

instability. Likewise, system frequency responses were also moderate andadequately damped with no indication of system underfrequency loadshedding or generator under/overfrequency operations.

Steady state conditions were reestablished with no further systemoperations.

A.4. Normal clearing of a three phase fault on the existing V.C. Summer ¹1generator switchyard bus ¹1 (NERC Category D-10 contingency)

Following a 1 second steady state period, a permanent three phase faultwas simulated at the V.C. Summer ¹1 bus ¹1. Since this is the bus that theV.C. Summer ¹1 generator is connected to, that generator was trippedwhen the fault was cleared. In addition, in order to prevent the FairfieldPumped Storage generators from becoming unstable, a Special ProtectionSystem that was identified as needed when V.C. Summer ¹2 goes intoservice will need to be installed at the V.C. Summer ¹1 switchyard in orderto trip those units as well. The operations to clear the fault and trip thegenerators will occur within 6 cycles from the appearance of the bus fault.

During the application of the fault, the voltage at the V.C. Summer ¹2 230kVbus dropped to 5.84kV. The V.C. Summer ¹1 230kV and 115kV OffsitePower Supply bus voltages dropped to 0.00kV and 19.93kV respectively.This allowed the degraded voltage and loss of voltage relay timers toinitiate. However, the voltages recovered enough to reset the loss ofvoltage relay timers within 13-14 cycles of the appearance of the fault. Thevoltage recovery allowed the degraded voltage relay timers to reset within29-32 cycles following the fault.

Rotor angle oscillations were moderate and were adequately damped withno indication of angular instability. There was no indication of voltageinstability. Likewise, system frequency responses were also moderate andadequately damped with no indication of system underfrequency loadshedding or generator under/overfrequency operations.

Steady state conditions were reestablished with no further systemoperations. The plots for this case are shown in

A.5. Three phase fault with normal clearing on the existing V.C. Summer ¹1generator bus ¹2 to Fairfield Pumped Storage Generators ¹ 5-8 (NERCCategory D-11 contingency)

Following a 1 second steady state period, a permanent three phase faultwas simulated on the 230kV transmission line that connects the V.C.Summer ¹1 bus ¹2 to the Fairfield Pumped Storage units ¹5-8. When thisline was opened these units which were operating in the pumping modewere taken off line. This represents the loss of a large load removed fromthe system as a result of a single event.

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 13 of 22

During the application of the fault, the voltage at the V.C. Summer ¹2 230kVbus dropped to 5.97kV. The V.C. Summer ¹1 230kV and 115kV OffsitePower Supply bus voltages dropped to 0.00kV and 20.21kV respectively.This allowed the degraded voltage and loss of voltage relay timers toinitiate. The voltage recovery differed between the 230kV and 115kV OffsitePower Supply buses but was sufficient to allow all relay timers to reset toprevent the switching of the Engineered Safeguard Features buses from theOffsite Power Supply buses. Transmission system voltages showed poorlydamped oscillations with a return to steady state conditions during anextended 60 second simulation.

Rotor angle oscillations were moderate but poorly damped during the 30second simulation due to the reduced system synchronizing torque duringreduced system load conditions. However, an extended simulation to 60seconds demonstrated an eventual return to steady state conditions.Switching the power system stabilizer at V.C. Summer ¹3 did not noticeablydegrade the rotor angle damping. There was no indication of angularinstability. Likewise, system frequency responses were also poorly dampedbut with no indication of system underfrequency load shedding or generatorunder/overfrequency operations.

Steady state conditions were reestablished with no further systemoperations.

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 14 of 22

V.C. Summer ¹3 STABILITY STUDY RESULTSPeak System Load Cases

A.1. Steady state conditionsA. Generator rotor angles demonstrate steady state condition.B. There was no indication of voltage instability.C. Generator frequencies show no deviation.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-001 compliance demonstrated.

A.2. Three phase fault with normal clearing on the V.C. Summer ¹3 generatorterminal 26kV bus

A. Moderate rotor angle oscillation for system generators with good dampingand no indication of instability.

B. There was no indication of voltage instability.C. Generator frequency responses are moderate and well damped with no

system UFLS or generator under/over frequency operations.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-002 compliance demonstrated.

A.3. Single line to ground fault with delayed clearing on the future V.C. Summer ¹3switchyard to the existing V.C. Summer ¹1 generator switchyard bus ¹2

A. Pronounced rotor angle oscillation for local generators with good dampingand no system instability.

B. There was no indication of voltage instability.C. Generator frequency responses are moderate and well damped with no

system UFLS or generator under/over frequency operations.D. Loss of offsite power to V.C. Summer ¹1 Engineered Safeguard Features

7.2kV buses not due to V.C. Summer ¹3 generator.E. NERC Reliability Standard TPL-003 compliance demonstrated.

A.4. Three phase fault with normal clearing on the existing V.C. Summer ¹1generator bus ¹1

A. Moderate rotor angle oscillation for system generators with adequatedamping.

B. There was no indication of voltage instability.C. Generator frequency responses are moderate and well damped with no

system UFLS or generator under/over frequency operations.D. Special Protection System to trip Fairfield Pumped Storage ¹1-8 required as

previously identified for V.C. Summer ¹2 generator.E. No negative impact on existing V.C. Summer ¹1 offsite power.F. NERC Reliability Standard TPL-004 compliance demonstrated.

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 15 of 22

V.C. Summer ¹3 STABILITY STUDY RESULTSSystem Light Load Cases

A.1. Steady state conditionsA. Generator rotor angles demonstrate steady state condition.B. There was no indication of voltage instability.C. Generator frequencies show no deviation.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-001 compliance demonstrated.

A.2. Three phase fault with normal clearing on the V.C. Summer ¹3 generatorterminal 26kV bus

A. Small rotor angle oscillation for system generators with poor but adequatedamping.

B. There was no indication of voltage instability.C. Generator frequency oscillations small with poor but adequate damping.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-002 compliance demonstrated.

A.3. Single line to ground fault with delayed clearing on the future V.C. Summer ¹3switchyard to the existing V.C. Summer ¹1 generator switchyard bus ¹2

A. Large rotor angle oscillation for system generators with poor damping.B. There was no indication of voltage instability.C. Generator frequency oscillations moderate with adequate damping.D. Loss of offsite power to V.C. Summer ¹1 Engineered Safeguard Features

7.2kV buses not due to V.C. Summer ¹3 generator.E. NERC Reliability Standard TPL-003 compliance demonstrated.

A.4. Three phase fault with normal clearing on the existing V.C. Summer ¹1generator bus ¹1

A. Moderate rotor angle oscillation for system generators with adequatedamping.

B. There was no indication of voltage instability.C. Generator frequency oscillations moderate and adequately damped.D. Special Protection System to trip Fairfield Pumped Storage ¹1-8 required

previously identified for V.C. Summer ¹2 generator.E. No negative impact on existing V.C. Summer ¹1 offsite power.F. NERC Reliability Standard TPL-004 compliance demonstrated.

A.5. Three phase fault with normal clearing on the existing V.C. Summer ¹1generator bus ¹2 to Fairfield Pumped Storage Generators ¹5-8

A. Moderate rotor angle oscillation for SCE&G generators with poor dampingdue to reduced system synchronizing torque during low system loadconditions.

B. There was no indication of voltage instability.C. Generator frequency oscillations moderate but poorly damped.D. No negative impact on existing V.C. Summer ¹1 offsite power.E. NERC Reliability Standard TPL-004 compliance demonstrated.

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 16 of 22

4. Stability Study Conclusions

This study demonstrates that the proposed V.C. Summer ¹3 generatorinterconnection to the SCE&G system is compliant with NERC ReliabilityStandards. There was no indication of voltage instability. None of thesimulations indicated that system LIFLS or generator under/overfrequencyoperations would occur. Neither does the interconnection have a negativeimpact on the existing V.C. Summer ¹1 offsite power quality. The cases thatresulted in the loss of offsite power for the V.C. Summer ¹1 generator werecaused by delayed clearing relay settings and not by the V.C. Summer ¹3generator. Several cases with faults located near the V.C. Summer ¹1 and theFairfield Pumped Storage units confirmed the need for a Special ProtectionSystem that will trip the Fairfield units to prevent instability. The need for thisSpecial Protection System was identified during the V.C. Summer ¹2 SystemImpact Study. The SCE8G Relay and SCADA Applications department hasidentified the operating features of such a scheme and will make the requiredsystem protection improvements.

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 17 of 22

III. Re uired Interconnection Facilities

The analyses performed in this study confirmed the results of the Feasibility Study andshow that constructing two new 230kV lines from the proposed VC Summer ¹3generator to near the Charleston area load center, plus additional transmissionimprovements described below, are required to reliably transmit SCE&G's ownershipportion of the 1,165 MW of the proposed VC Summer ¹3 generator from the VCSummer area to the remainder of the SCE&G system. Additionally, the off-peakanalysis identified the need for a series reactor on the VC Summer ¹1-Newport (Duke)230kV line to limit the power flow on that line.

The required transmission improvements:

1. Construct VC Summer New-St George 230kV Double Circuit B1272 line (135 mi)(Add 2 230kV terminals at VC Summer New using breaker-and-a-halfdesign)

2. Construct VC Summer New-VC Summer ¹1 Bus ¹1(Add 230kV terminal at existing VC Summer ¹1 Bus ¹1)(Add 230kV terminal at VC Summer New using breaker-and-a-halfdesign)

3. Establish a St George 230kV Substation using breaker-and-a-half design(6 terminals - 9 breakers)(Future 2 terminals - 3 breakers)(Add land)

4. Fold-in the Canadys-Santee 230kV line at St George 230kV

5. Upgrade the Canadys-St George 230kV line to B1272(Upgrade Canadys terminal)

6. Fold-in the Wateree-Summeiville 230kV line at St George 230kV

7. Upgrade the St George-Summerville 230kV line to B1272(Upgrade Summerville terminal)

8. Upgrade Saluda-Georgia Pacific 115kV Double Circuit line to 1272(Upgrade Saluda terminal)

9. Install a 230kV Series Reactor (25% on a 500 MVA base) on the VC Summer ¹1-Newport (Duke) 230kV line

Add six (6) terminals (8 breakers) to the VC Summer New substation using breaker-and-a-half design.

10.0ne - for VC Summer ¹3 generator step up transformer11.0ne -for VC Summer ¹3 station service

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Exhibit Q-2 (Exhibit No (HCY-2))Page 18 of 22

12. One - for the new 230kV line to the existing VC Summer ¹1 bus ¹113. Two - for the 2 new 230kV lines to St George 230kV14.0ne - for the new 230kV line to Sandy Run (Santee Cooper)

To resolve overstressed conditions of the breakers as described in the Short CircuitAnalysis section, Transmission Planning recommends replacing the following breakerswith higher interrupting capability breakers:

As stated in the stability analysis section, several cases with faults located near the VCSummer ¹1 and the Fairfield Pumped Storage units revealed a need for a SpecialProtection System that will trip the Fairfield units to prevent instability. The SCE&GRelay and SCADA Applications department has identified the operating features of sucha scheme and will make the required system protection improvements.

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IV. En ineerin Desi n & Cost

Exhibit Q-2 (Exhibit No. (HCY-2))Page19of 22

Engineering Single line Layout & Substation Arrangement

VC Summer W

Transmission Single Line

To Iknh Rn er 'I'PeltI o Nm(Duke I

Sruuh RunISLI'SAi

(.untdchulUl.( SLIPSAi

To '(Tard(S('Ftii

t(ahtauh FLit I'reckIs( PSAi i S("PSAI

Sl Ocl rdcI SL'PSAI

t''7'oI(kith Ivood

I SL PSAI

(hrnvdki(ii.l'SA(

lnimdtontreat

I 'rkC I lrllnl1

t SL'IIII I

IknllTl,'rr(i(P ti i I'mcknd

(SLTI(il

Kdlun I S( Ft i

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To SRS( S(:ER(i!

To Yeinaacee(S( FA(it

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230kr Rindle Line 17(asrnniR d -;I iv mitalh(nnithu ' Lx( uil( lrlc linn.er n- 1.7xpru! d t;I luaiPurpk - i.ui«c i Ti llur il'ern To hittr. (,r

I SL'PSAI

Pepperhts I St7RIRF

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shitrI SI TX (

To Ten(acr«eI Sl:PTU I

'(Snu h(reekIS(.'RR(i(

Pat«1 PLI eIS( FX( I

19

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 20 of 22

Substation Arrangement

VC Summer ¹3

Faafutd ul tk "-,2

Nuclear —.1

tV acus cl'0 (S alit re)

Neu)tert

Bach Raau 0trrke)

Neatrcrn (Saruee)

)Var d

St (iearue=

St Geotae=

Satat) Rrar (Saut

Lake Seurur

Lake tttta wy =.,1

Detary Tur ace =1

20

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 21 of 22

Substation Arrangement

St George 230kV

YC'S Lane =t EVatteree

%'CS Line =.' au tee

Cauadya Suutuletville

Futlwe Futta e

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Exhibit Q-2 (Exhibit No. (HCY-2))Page 22 of 22

B. Transmission & Substation Cost

All cost estimates are in 2006 dollars.

1. Construct VC Summer New-St George 230kVDouble Circuit B1272 line (135 miles) ............ ....$153,950,000

2. Construct VC Summer New-VC Summer ¹1 Bus ¹1)............................$600,000(Add 230kV terminal at existing VC Summer ¹1 Bus ¹1)..............$ 1,100,000

3. Construct St George 230kV Substation usingbreaker-and-a-half design .$11,400,000

4. Fold-in the Canadys-Santee 230kV line at St George 230kV.............$ 1,100,000

5. Upgrade the Canadys-St George 230kV line to B1272 ... .....$7,300,000

6. Fold-in the Wateree-Summerville 230kV line at St George 230kV.....$ 1,100,000

7. Upgrade the St George to Summerville 230kV line to B1272...........$ 15,300,000

8. Upgrade Saluda-Georgia Pacific 115kV Double Circuit line to 1272 $11,900,000

9. Add six (6) 230kV terminals (8 breakers) at VC Summer New usingbreaker-and-a-half design. .$ 12,000,000

10. Install a 230kV Series Reactor (25% on a 500 MVA base) on theVC Summer ¹1-Newport (Duke) 230kV line..................................$3,800,000

Replace overstressed breakers

11. Three (3) 230kV breakers12. Eight(8) 115kV breakers ....

. $660,000. $ 1,200,000

Total Cost Estimate. . $221,410,000

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Exhibit Q-3 (Exhibit No. (HCY-3))Page 1 of 7

A S CANA COMPAN Y

Generator Interconnection Facilities Study

SCE8 G V.C. Summer Nuclear t2

Prepared for:SCE&G Nuclear Group

April 14, 2008

Prepared by:SCE8 G Transmission Planning

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Exhibit Q-3 (Exhibit No. (HCY-3))Page 2 of 7

TABLE OF CONTENTS

General Discussion.

I. Generator Information.

II. Cost Estimates and Completion Dates

I II. Facilities Classifications

IV. Electrical Switching Configuration .

Page 3

Page 4

Page 4

Page 6

Page 7

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Exhibit Q-3 (Exhibit No. (HCY-3))Page 3 of 7

Generator interconnection Facilities Study

SCE&G V.C. Summer Nuclear ¹2

A Generator Interconnection Facilities Study is an extension of the previous GenerationInterconnection System Impact Study, and specifies and estimates the cost of theequipment, engineering, procurement and construction work needed to implement theconclusions of the Interconnection System Impact Study in accordance with Good UtilityPractice to physically and electrically connect the Interconnection Facility to theTransmission System. A Generator Interconnection Facilities Study also identifies theelectrical switching configuration of the connection equipment, including, withoutlimitation: the transformer, switchgear, meters, and other station equipment; the natureand estimated cost of any Transmission Provider's Interconnection Facilities andNetwork Upgrades necessary to accomplish the interconnection; and an estimate of thetime required to complete the construction and installation of such faci(ities.

General Discussion

The SCE8G Nuclear Group has applied for interconnection of a new 1375 MVA nucleargenerator near the existing V.C. Summer site. This new generator would be jointlyowed by SCEBG and Santee Cooper, SCEBG would own 55% and Santee Cooperwould own the remaining 45%. In this study Santee Cooper's portion of the generatoroutput was represented as delivered to the Santee Cooper system.

The previously completed System Impact Study recommended the followingtransmission line improvements:

1. Construct VC Summer-Wlnnsboro- Killian 230kV~ (add 230kV terminal at Killian)

2. Construct VC Summer-Lake Murray 230kV~ (add 230kV terminal at Lake Murray)

3. Construct VC Summer ¹2-VC Summer ¹1 bus ¹2~ (add 230kV terminal at VC Summer ¹1 bus ¹2)

4. Construct VC Summer ¹2-VC Summer ¹1 bus ¹3~ (add 230kV terminal at VC Summer ¹1 bus ¹3)

5. Upgrade existing Denny Terrace-Lyles 230kV6. Add a 3rd 230/115kV 336 MVA auto transformer at Lake Murray7. Add a 3rd 230/115kV 336 MVA auto transformer at Denny Terrace8. Upgrade existing Saluda-McMeekin 115kV line9. Upgrade existing Lake Murray-McMeekin 115kV line10. Upgrade existing Lake Murray-Saluda 115kV11.Add second 230kV bus tie breaker at Denny Terrace

Construct a new 230kV generator substation at the proposed site using a breaker-and-a-half design with ten 230kV terminals

Construct Transmission from VC Summer ¹2 Generator to VC Summer ¹2 Switchyard

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Exhibit Q-3 (Exhibit No. (HCY-3))Page 4 of 7

Re-terminate VC Summer area lines to the VC Summer ¹2 Substation

1. Re-terminate Bush River (Duke) 230kV line to VC Summer ¹2 substation2. Re- terminate Newberry (SCPSA) 230kV line to VC Summer ¹2 substation (paid

by SCPSA)3. Re-terminate Ward 230kV line to VC Summer ¹2 substation4. Re-terminate Lake Murray 230kV ¹1 line to VC Summer ¹2 substation5. Re-terminate Denny Terrace 230kV ¹1 line to VC Summer ¹2 substation

Re-terminate VC Summer area lines to the VC Summer ¹1 Substation

1. Re-terminate Blythewood (SCPSA) 230kV line to VCS bus ¹1 (paid by SCPSA)2. Re-terminate Pineland 230kV line to VCS bus ¹33. Re-terminate Denny Terrace 230kV line ¹2 to VCS bus ¹34. Re-terminate Newport (Duke) 230kV line to VCS bus ¹2

Replace overstressed1. 230kV breakers-92. 115kVbreakers-9

In the future, SCE&G Transmission Planning will periodically review the results of thisInterconnection Faciiities Study to determine if the recommended transmissionexpansion and the associated cost estimates remain valid.

I. Generator Information

The generator design consists of a single nuclear unit and one step-up transformer.The generator unit will have a maximum gross MVA output capacity of 1,375 MVA anda maximum continuous net MW of 1,165 MW.

The generator design consists of the following information:MVA — gross: 1375MW — net: 1165Power Factor: between .90 and 1.05Voltage: 22kvSpeed: 1800 rpmX'd-sat.: 0.465 PU; X"d-sat.: 0.325 PUX2-sat.: 0.320 PU; XO: 0.237 PU

II. Cost Estimates of Transmission Provider's Interconnection Facilities andNetwork U rades and Com letion Dates

The Table below includes the cost estimate for the required Transmission ProviderInterconnection Facilities, the required Network Upgrades and the estimated completiondate for each of these required projects.

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Exhibit Q-3 (Exhibit No. (HCY-3))Page 5 of 7

VC Summer Unit 02 Transmissi n s astimatosEscalated at d%%u pgr %sar from 2000

pr lorna m 3 h 4 I 45 dnme

8 dg t2000

6 dgot2009

Suds tmto

6 dg t2011

ll dg2012

6 40124M

Bdgt2014

8 dget Budget2015 2010

Budget2017

Budg t2010

Summer Un t ¹2 230KV Swttohyenl - Co W asumma fn-Klllren -230KY Line- constr rt 01272

angl~ shalt — no sddrbonel RIW required end 0stngleehetlangleolrcullfor3mlie. A *

ddltm IRIW*t70R I* g kl m gRIWfPtnelend to K Iten- eppr s28 seas Bl 80 DDD DerACI~

Kll Add 230KvT m — summer's I a

12I3U2013

12I3U2015

12I3U2015

12I3V201 5

1,000,000 15,000,000

50D,ODD

800,000

IT,Doo,otto

1,500,000

3.DOO,DOD

Bdgtm Nd14,00ll,ooo 10.000.000

840,000

ID,000,000 ID.OCO,OOO

13,000,000

35,000,BIS

840,000

23,000,000

dditl I RlufL I M yT Add230KVTVCSR!S U 4¹2-230KvT I 0 ¹2-C stnctAmu e075mlles U 4¹i-444230nvy nntoausm-Comi t6 U kgbz!DKUT t 6 s¹3 — conslmctAssu e075 Oe

5 U d¹l-Add230Kvrermloaus¹3-

C nny Tenses Lyles 230KV- Rebu Id to 81272A 275

VCS A A I I 230kVI t VCStil Sm

VCS A R I

' 230kVL' VCSO2S b

LekeM WT ~ — Add3 336Amb k

C ny Terrece-Add 3'36 A I b kl230kVBT

Sold MM d«115KVL -Upg de(Appro02Lake M yT -M M k IIOKv UU M A 06 k

L k M y.s I d 115KvL UPg d (rbP05v* 115KVPRCBUpg d I t pl lha gA 0 PRCBs

V I 230KVPRCBUpg d I t pt R 0 gA 9 PRCIM

VCS U ¹2 U I ICS b23ckVL, C

vcs, IIATInt U ~ 423 b23okvL .C sm

vcs 7 llavs nl ML .R I U t2

VC S S b. 230k V 86 8 T ba trl 8 tl3

12I3U2015

12/3V201 3

12I3il2013

12I3II2013

12nv2013

ttiSICOIS

12I3U2013

12I3U2013

12I3U2015

12I3U2015

12I362010

12ISC2010

12/3V2015

12I3U2015

12131I2015

12I3U2013

12I3U2013

.'2 I '2NB

1 I 2ttcy

70.000

250,000

0404KO

040,000

mo,ooo

95D,OOO

1.800.000

200.000

500 000

500,000

04D,000

100,000 2.000,0CO

3,000,(00 4,00ll,ooo

5.000,000 6,000,000

700.000

OSO.OOO

800,000 3,000,000

1,300,000 5,0D0,000

040,000

m0.000

840,000

040,000

040,000

2,100,000

950,000

1,000,000

7,000,000

11,000,400

200,000

700,000

630,000

3.000,000

0,300,000

500,000

SOO,OOO

70,000

250,000

0 32D,D00 0 1,000,000 16,300,DDO 20,010,000 34,200,000 52,410,000 0 132,64D,400

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III. Facilities Classifications

Exhibit Q-3 (Exhibit No. (HCY-3))Page 6 of 7

The Facilities Study report must identify and estimate the cost of any TransmissionProvider's Interconnection Facilities and Network Upgrades necessary to accomplishthe interconnection. The diagram below includes color and line style indications ofwhich facilities fall into the classification of Network Upgrades, Transmission Provider'sInterconnection Facilities or Interconnection Customer's Interconnection Facilities. Costestimates for all Network Upgrades and Transmission Provider's InterconnectionFacilities are included in Section II of this report. The diagram below is different fromthe diagram in the System impact Study and reflects the most recent substation design.

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Exhibit QH3 (Exhibit No. (HCY-3))Page 7 of 7

IV. Electrical Switchin Confi uration

P-UP POWERSFORME

AUXILIFRSFO M R

DEADENDSTRUCTURE

8 ROAD

DEAOEND/POWERCIRCUIT BREAKER

STRUCTURE

ERDWI

ICALU TEDT E

ER OA Y VOU TEDWI E

NOTE;THIS IS ALSOAN ALTERNATEFOR UNIT 3 3

0'0'0'30XVPOWERCIAO/IT3 REAKE IL

DEAOEND/SWITCHAND BUSSTRUCTLRE

VERTICALLYMOUNTEDSWITCHES

NN SFO'NN S

V C, SUMMER UNIT TWO

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Exhibit QP (Exhibit No. (HCY-4))Page 1 of 8

A SCANA COMPANY

Generator Interconnection Facilities Study

SCE&G V.C. Summer Nuclear ¹3 — Revision ¹2

Prepared for:SCEB G Nuclear Group

April 10, 2008May 27, 2008 — Revision ¹1May 29, 2008 — Revision ¹2

Prepared by:SCE&G Transmission Planning

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Exhibit QX (Exhibit No. (HCYP))Page 2 of 8

May 29, 2008 — Revision ¹2This revision renames and rearranges one of the associatedprojects in the narrative and in the cost estimate table forclarification. The rest of the report is unchanged andincluded in its entirety.

May 27, 2008 — Revision ¹1This report corrects a double entry line item in the costestimate for the Vc Summer ¹3 interconnection. The rest ofthe report is unchanged and included in its entirety.

TABLE OF CONTENTS

General Discussion.

I. Generator Information

II. Cost Estimates and Completion Dates

III. Facilities Classifications

Page 3

Page 4

Page 4

Page 6

IV. Electrical Switching Configuration

V. Facilities Diagram with VC Summer ¹2 and ¹3 ...

. Page 7

..... Page 8

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Exhibit Q-4 (Exhibit No. (HCYR))Page3of8

Generator Interconnection Facilities Study

SCE8G V.C. Summer Nuclear 43

A Generator Interconnection Facilities Study is an extension of the previous GenerationInterconnection System Impact Study, and specifies and estimates the cost of theequipment, engineering, procurement and construction work needed to implement theconclusions of the Interconnection System Impact Study in accordance with Good UtilityPractice to physically and electrically connect the Interconnection Facility to theTransmission System. A Generator Interconnection Facilities Study also identifies theelectrical switching configuration of the connection equipment, including, withoutlimitation: the transformer, switchgear, meters, and other station equipment; the natureand estimated cost of any Transmission Provider's Interconnection Facilities andNetwork Upgrades necessary to accomplish the interconnection; and an estimate of thetime required to complete the construction and installation of such facilities.

General Discussion

The SCE&G Nuclear Group has applied for interconnection of a new 1375 MVA nucleargenerator near the existing V.C. Summer site. This new generator would be the thirdnuclear generator on this site and would be jointly owned by SCE&G and SanteeCooper, SCE&G would own 55% and Santee Cooper would own the remaining 45%. In

this study Santee Cooper's portion of the generator output was represented asdelivered to the Santee Cooper system.

The previously completed System Impact Study for VC Summer ¹3 recommended thefollowing transmission line improvements:

1. 230KV Switchyard Additions for Unit ¹3 — Add six (6) 230kV terminals (8breakers) at VC Summer New using breaker-and-a-half design

2. Construct VC Summer New-St George 230kV Double Circuit B1272 line (135miles)

3. Construct VC Summer New-VC Summer ¹1 Bus ¹1)(Add 230kV terminal at existing VC Summer ¹1 Bus ¹1)

4. Construct St George 230kV Substation using breaker-and-a-half design5. Fold-in the Canadys-Santee 230kV line at St George 230kV6. Upgrade the Canadys-St George 230kV line to B12727. Fold-in the Wateree-Summerville 230kV line at St George 230kV8. Upgrade the St George to Summerville 230kV line to B12729. Upgrade Saluda-Georgia Pacific 115kV Double Circuit line to 127210. Install a 230kV Series Reactor (25% on a 500 MVA base) on the VC Summer ¹1-

Newport (Duke) 230kV line

Replace overstressed breakers

11. Three (3) 230kV breakers12. Eight (8) 115kV breakers

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Exhibit QP (Exhibit No. (HCYP))Page 4 of 8

In the future, SCE&G Transmission Planning will periodically review the results of thisInterconnection Facilities Study to determine if the recommended transmissionexpansion and the associated cost estimates remain valid.

I. Generator Information

The generator design consists of a single nuclear unit and one step-up transformer.The generator unit will have a maximum gross MVA output capacity of 1,375 MVA anda maximum continuous net MW of 1,165 MW.

The generator design consists of the following information:MVA — gross: 1375MW- net: 1165Power Factor: between .90 and 1.05Voltage: 22kvSpeed: 1800 rpmX'd-sat.: 0.465 PU; X"d-sat.: 0.325 PUX2-sat.: 0.320 PU; XO: 0.237 PU

II. Cost Estimates of Transmission Provider's Interconnection Facilities andNetwork U rades and Com letion Dates

The Table below includes the cost estimate for the required Transmission ProviderInterconnection Facilities, the required Network Upgrades and the estimated completiondate for each of these required projects.

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Exhibit Q4 (Exhibit No. (HCY4))Page 5 of 8

V Umm r nit¹ nsmi i E I'sca/ate¹at 4% Der year from 200¹

Pm/ant Non*

23DKVS lt hy NAddel I U k¹3

Sahed lad slidOne

12/I/2010

0 dgn2000

8dglZOOS

8 46 I2pt Il

Baden2011

Il dg I 0 dget2012 Z013

Sudg I2014

8 dpet2016

8 dg IID'I 6

700.DDO

Sdgt2417

s.40o.ooo

8 dgaZNO

11.000.000 10,900,000

VCS¹2NSt 8 G 230kV-C* *t tb127211 135

12n/2018 500,000 1,500,0CO 100,000,000 144,320,000 246.320.DOD

0 U h¹3-230KVTetos a¹1- 12/U2010C ku t A e/tne075

12nl2018VCS¹I,S ¹I.Add T t VCS¹23 bVCS U talk ¹23 b230kVL 12/I/2010

900,0DO

1.700,000

600,MO

900,00D

1,700.000

400.000

VC S OAT Ol ¹2 S b 23DkV

St G G 230kys tehng sat/ouC tse K

12n/2010

12/I/2018 240,000 O,OOO,OOO

600,000

10,000,000

600,000

m,240,000

0 dy -Santee230ku F kllnt SLG 2mkVC* dy -St G G 230kV:Upg d

01272W t -S mlle230kV F Id/ tSt G 2301 V

12/IGOI0

12/I/2010

12/I/2018

S IHyd -G Pao115kVD ubleCklU dt 1272

12/I/2010

VCS 41 S b Add 230kV Se m R aoto 12/I/2DIO8 *¹Dk LI

St.G nl -S ' 230kV.Upg d 12N/2DISt 01272

600.000

400.000

IC0,000

4,000.000

0,000.000

S,OOD,OOO

1,100,00D

1,760,DOD

7,000,000

1,760.000

16,000,000

11,000,000

5,000,000

1,700,0DO

11,000,000

1,760,000

24,400.000

19,100,000

6,100,000

V,l 230KVPRCSUpg dIt t RU Aa 3PRCSV N IISKVPRCBUpg d

12n/2010

TZ/tl20IB

1,056,000

1,920,000

1,056,000

1,920,000

600,000 3,700,000 135,500,000 215,530,000 355,236,000

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III. Facilities Classifications

Exhibit QX (Exhibit No. (HCYX))Page 6 of 8

The Facilities Study report must identify and estimate the cost of any TransmissionProvider's Interconnection Facilities and Network Upgrades necessary to accomplishthe interconnection. The diagram below includes color coded indications of whichfacilities fall into the classification of Network Upgrades, Transmission Provider'sInterconnection Facilities or Interconnection Customer's Interconnection Facilities. Costestimates for all Network Upgrades and Transmission Provider's InterconnectionFacilities are included in Section II of this report.

Sahf)eld S1 R —..l

NucleN 1

)Veuubu u cdudee)

Neauact

Buab Scccc (Duke)

Ncudlcu)'Seutcc)

)ru d

Sl CNalac =

Sl Dc lac=

,)aud) Ruu esaut

Lake hhal «T

Luke hbuled u1

Duulr Tucaceu1

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Exhibit QX (Exhibit No. (HCYP))Page 7 of 8

IV. Electrical Switchin Confi uration

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V. Facilities Dia ram with VC Summer ¹2 and VC Summer ¹3

Exhibit Q-4 (Exhibit No. (HCY4))Page 8 of 8

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Exhibit No. (HCY-5Page I oft

A SCANA COMPANY

Generator Interconriection Feasibility StudyFor

SCE8G V.C. Summer Nuclear C2

Prepared for:SCE8G Nudear Group

August 4, 2006

Prepared by:SCE&G Transmission Planning

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Exhibit No. (HCY-5)Page 2 of19

TABLE OF CONTENTS

General Discussion..

I. Generator Information.

... Page 3

..... Page 4

II. Transmission Studiesa. Power Flow Analysis.b. Short Circuit Analysis.

. Page 5... Page 14

III. Preliminary Recommendations .

IV. General Engineering Design .

V. Cost Estimates

... Page 15

... Page 17

Page 19

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Exhibit No. (HCY-5)Psge3 of19

Generator Interconnection Feasibility Study forSCAG V.C. Summer Nuclear ff2

en rat r Interconnection 'bii'ies areintended to be preliminary studies toaid the requestor in determining If the application should advanced to additional, mon.detailed and more costly studies or be withdrawn. These additional studies include theSystem Impact Study, Optional Upgrade Studies and the Factiity Study. InterconnechonFessibiiify Studies do not determine the hnal facilities and costs of interconnecting therequested generafor to the existing transmission system.

The SCE8G Nudear Group has applied for interconnection of a new f 375 MVA nudeargenerator near the existing V.C. Summer site. This new generator would bs jointlyowed by SCE&G and Santee Cooper, SCE&G would own 55'Yo and Santee Cooperwould own the remaining 459o. In this study SCE&G simulated Santee Cooper's portionof the generator being delivered to the Santee Cooper system.

SCE&G Transmission Planning is participating in a joint study with Santee Cooper andother interconnected transmission providers to evaluate the effect of this generator andother planned generators in the region. Results of this joint study, such as short circuit,transient stability and power transfer capabilities, may affect the final recommendatlonsincluded in this report

The format of the report is as follows:

I. Generator Information (provided by the SCE&G Nudear Group)II. Transmission Studies

A. Power Flow AnalysisB. Short Circuit Analysis

III. Preliminary RecommendationsIV. General Engineering DesignV. Cost Estimates

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I. Generator Information

Exhibit No. (HCY-5)Page 4 of 19

The generator design consists of a single nudear unit and one step-up transformer.The generator unit will have a maximum gross MVA output capacity of 1,375 MVA anda maximum net MW of 1,165 MW.

The generator design consists of the following information:MVA- gross: 1375MW- net 1165Power Factor. between .90 and 1.05Voltage: 22kVSpeed: 1800 rpmX'*sat.: 0.465 PU; X"d-sat: 0.325 PUX2-sat.: 0.320 PU; XO: 0.237 PU

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II. Transmission Studies

A. Power Flow Analysis

Exhibit No. (HCY-5)Page 5 of 19

For the proposed generator interconnection of the VC Summer ¹2 generator,Transmission Planning performed analyses of:

1. Base case conditions (no outsges) simulating normal conditions2. N-1 conditions simulating single facility outages.of each transmission facility on

the SCE&G system3. Selected n-2 conditions simulating the loss of two facilities on the SCE&G

transmission system

This study is based on future projected conditions on the SCE&G transinission system,simulating 2015 peak summer conditions and assumes that the following transmissionimprovements will be made to SCE&G's Columbia area transmission system prior to2015. These transmission improvements are currently scheduled snd are needed forother system needs:

1. Upgrade Lyles-William Street 115kV line2. Upgrade Lyles-Denny Terrace 115kV line ¹1 snd ¹23. Add a 2~ Lake Murray 230l115kV auto transformer4. Increase thermal rating on the Denny Terrace-Lyles 230kV line

Additionally, this study assumes that the following prcposed transmission modificabonswill be made by Santee Cooper to their transmission system ss part of theirinterconnection to the proposed generation. These transmission improvements wereprovided by Santee Cooper.

1. Add a VCS-Winnsboro 230kV line with 230/69kV transfwmers at VMnnsboro.2. Add s Winnsboro-Richburg 230kV line with 230$9kV transformers at Richburg.3. Add a Richburg-Flat Creek 230kV line

u -I ctionofthe ro d1166M atVC u me 30kVwithnos s I lo ovements

For the initial analysis, 1,165 MW is injected at the VC Summer 230kV bus with noafAliated modncations to the SCE&G transmission system. With the existing VCSummer net generation of 966 MW and the Fairlield Pumped Storage net generation of608 MW, the total net MW generation connected to the 230kV system in the vicinity ofthe VC Summer site is 2,739 MW.

Base Case ConditionsThere am no overloaded facilities in the base case (no outsges). However, severalexisting 230kV lines in the VC Summer area sre highly loaded:

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Exhibit No. (HCY-5)Page 6 of 19

~ The VCS-Pineland 230kV line loads to 75% of its 475 MVA Normal Rating~ The VCS-Denny Terrace 230kV line loads to 68% of its 475 MVA Normai Rating~ The VCS-Blythewood (Santee Cooper) 230kV line loads to 58% of its 478 MVA

Normal Rating~ The VCS-Lake Murray 230kV line loads to 80% of its 704 MVA Normal Rating~ The Denny Terrace-Lyles 230kV line loads to 73% of its 475 MVA Normal Rating~ The Parr-Denny Terrace 230kV line loads to 66% of its 704 MVA Normal Rating.

~N-

~intone

The n-1 analyses show the following overload conditions due to the additionalgeneration:

The n-2 analyses show the following overload conditions due to the additionalgeneration:

Ovedoaded Fadmy

Parr-Den Terrace 230kV line

Parr-Denn Terrace 230kV line

Parr-Denn Terrace 230kV line

VC Summer Parr 230kV line

VC Summer Parr 230kV kne

VC Summer Parr 230kV line

VC Summer Parr 230kV line

YC Summer Parr 230kV line

VC Summer Parr 230kv line

EmergencyRatingMVA

755

755

755

636

Overload

110

135

123

112

110

109

Contingency(s)

VC Summer-Denny Terrace 230kVline and VC Summer-Lake Murray230kV line

VC Summer-Pineland 230kV line andVC Summer-Lake Murra 230kV line

VC Summer-Pineland 230kV line andVC Summ'er-Denny Tenace 230kVline

Other VC Summer-Parr 230kY lineand VC Summer-Lake Murray 230kVtine

Other YC Summer-Parr 230kV lineand VC Summer-Denny Terrace230kV line

Other VC Summer-Pan 230kY lineand VC Summer-Pineland 230kV line

Other VC Summer-Parr 230kY lineand VC Summer-Btythewood 230kVline

Other VC Summer-Parr 230kV lineand VC Summer-Winnsbcro 230kVline

Other VC Summer-Parr 230kV lineand VC Summer-Pomaria 230kV line

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VC Summer Pan 230kV line

VC Summer Parr 230kV line

L les-William Street 115kV line

L les 230/115kV auto transf

VC Summer-Pineland 230kV line

VC Summer-Pineland 230kV line

VC Summer-Pineland 230kV line

VC Summer-Pineland 230kV line

VC Summer-Pineland 230kV lineVC Summer-Denny Terrace 230kVline

VC Summer-Denny Terrace 230kVline

VC Summer-Denny Terrace 230kVline

VC Summer-Lake Murra 230kV line

VC Summer-Lake Murra 230kV line

VC Summer-Lake Mu 230kV line

Denn Terrace-L les 230kV line

Denny Terrace 230/115kV auto transf¹1Denny Terrace 230/115kV auto transf¹1

Denny Terrace 230/115kV auto transf¹1

Denny Terrace 230/1 15kV auto transf¹1

336

510

510

510

510

510

510

510

510

755

755

510

336

108

104-107

116

101

125

115

101

101

132

125

112

101

105-130

133

107

Exhibit No. (HCY-5)Pag 7of19

Other VC Summer-Pan 230kV lineand VC Summer-Timberlake 230kVline

Other VC Summer-Psn 230kV lineand one of various 230kV facilities inColumbia area.VC Summer-Lake Murray 230kV lineand L tes-Edemttood 230kV line

Denny Terrace 230/115kV auto transf¹1 and Denny Terrace 230/115kVauto transf ¹2Parr&enny Terrace 230kV line andVC Summer-Lake Murra 230kV line

Parr&enny Terrace 230kV line andVC Summer-Denny Terrace 230kVline

VC Summer-Denny Terrace 230kVline and VC Summer-Lake Murray230kV line

Parr-Denny Terrace 230kV line andWateree Generator or GSUParr-Denny Terrace 230kV line andWateree-Huron 230kV lineParr-Denny Terrace 230kV line andVC Summer-Lake Murra 230kV lineParr-Denny Terrace 230kV line andVC Summer-Pineland 230kV line

VC-Pineland 230kV line and VCSummer-Lake Murra 230kV line

Parr-Denny Terrace 230kV line andVC Summer-Denny Terrace 230kVline

Parr-Denny Terrace 230kV line andVC Summer-Pineland 230kV line

VC Summer-Denny Terrace 230kVline and VC Summer-Pineland 230kVline

VC Summer-Lake Murray 230kV lineand one of various 230kV facilities inColumbia area.Denny Terrace 230/115kV auto transf¹2 and Denny Terrace-Lyles 230kVline

VC Summer-Lake Mumsy 230kV lineand Denn Terrace les 230kV line

Lyles 230/1 15kV auto transf andDenny Terrace 230/115kV auto transf

VC Summer-Lake Murray 230kV lineand Denny Terrace 230/115kV autotransf ¹2

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Denny Tenace 230/115kV auto trans/¹2Denny Terrace 230/1 15kv auto trans/¹2

Denny Terrace 230/115kV auto transf¹2

Denny Terrace 230/115kV auto transf¹2

Lake Murray 230/115kv auto transf¹1

Lake Murray 230/1 1 5kv auto transf¹2

Lake Murra -Saluda 115kV line

Saluda-McMeekin 115kv line

Saluda-Whitehall 115kV line section

336

255

132

124

110

113

105

Exhibit No. (HCY-5)Pag 8of19

Denny Terrace 230/1 15kV auto transf¹1 and Denny Terrace-Lyies 230kvlineVC Summer-Lake Murray 230kv lineand Denn Tenace-L les 230kv line

Lyles 230/115kv auto transf andDenny Terrace 230/115kv auto transf¹1VC Summer-Lake Murray 230kV hneand Denny Terrace 230/1 15kV autotrans/ ¹1Lake Murray-Edenwood 230kV lineand Lake Murray 230/115kv autotrans/¹2Lake Murray-Edenwood 230kv lineand Lake Murray 230/115kV autotranst ¹1Bush River-Parr 230kv line andSaluda-McMeeldn 115kv lineBush River&an 230kv line and LakeMurra -Saluda 1'l5kV lineLyles-tNilliam Street 115kV line andCoit-Vista South 115kV line

Ru ¹2-Rebuild e oad o I r lines

For Run ¹2, the following transmission modNcations are made as a result of overloadedfacilities that were identNed in the Run ¹1 n-1 analyses:

1. Upgrade the Parr-VC Summer 230kV line ¹1 to B1272 conductor2. Upgrade the Parr-VC Summer 230kV line ¹2 to B1272 conductor3. Upgrade the Denny Terrace-Lyles 230kV line to B1272 conductor

Also, the Run ¹1 n-2 analyses showed that each of the four major transmission linesleaving the VC Summer area to the Columbia load center overload for the loss ofvarious and paired combinations of the other three lines. We first addressed this byconsidering if upgrading the two lines with the lowest existing capacity is adequate:

5. Upgrade the VC Summer-Pineland 230kV line to B1272 conductor6. Upgrade the VC Summer-Denny Tenace 230kV line to B1272 conductor

Base Case ConditionsThere are no overloaded facilities in the Run ¹2 base case (no outages).

N-1 ConditionsThere are no overloaded facilities in the Run ¹2 n-1 analyses due to the additionalgeneration.

Seiected N-2 Conditions

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Exhibit No. (HCY-5)Page 9 of 19

The Run ¹2 n-2 analyses show the following overload oonditions due to the additionalgeneration-.

Overloaded Facility

Parr-Denn Terrace 230kv line

EmergencyRating OverloadMVA

Contingency(s)

VC Summer-Denny Terrace230kV line and VC Summer-Pineland 230kV tne

L les-Williams Street 115kV line

L les-Williams Street 115kV line

L les 230/115kv auto transf

L les 230/115kV auto transf

VC Summer-Lake Murray 230kvline

Denny Terrace 230/115kv autotransf ¹1

Denny Terrace 230/115kv autotransf ¹1

Denny Terrace 230/115kV autotransf ¹1

Denny Terrace 230/1 15kv autotransf ¹1

Denny Terrace 230/115kV autotransf ¹2

Denny Terrace 230/115kV autotransf ¹2

Denny Terrace 230/115kV autotransf ¹2

Denny Terrace 230/115kv autotransf ¹2

Lake Murray 230/'l15kv autotransf ¹1

Lake Murray 230/115kv autotransf ¹2

255

336

336

121

101

109

110

142

131

115

101

141

114

105

119

119

YC Summer-Lake Murray230kv line and Lyl~denwood230kv lineVC Summer-Lake Murray230kY line and Denny Terrace-L km 230kv lineVC Summer-Lake Murray230kv line and Lyles-Edenwood230kv line

Denny Terrace 230/1 15kV autotransf¹1 and Denny Terrace230/115kV auto transf ¹2Parr-Denny Terrace 230kv lineand VC Summer-Denny Terrace230kV line

Denny Terrace 230/115kV autotransf ¹2 and Denny Terrace-L les 230kV kneVC Summer-Lake Murray230kv line and Denny Terrace-L les 230kv line

Lyles 230/115kV auto transf andDenny Terrace 230/115kV autotmnsf ¹2Denny Terrace-Lyles 230kV lineand loss of one of three 115kvlines in the Pineland areaDenny Terrace 230/1 15kV autotransf ¹1 and Denny Terrace-L les 230kV lineVC Summer-lake Murray230kV line and Denny Terrace-L les 230kV line

Lyles 230/115kv auto transf andDenny Terrace 230/1 15kV autotransf ¹1VC Summer-Lake Murray230kv line and Denny Terrace230/115kv auto transf ¹1Lake Murray-Edenwood 230kVline and Lake Murray230/115kV auto transf ¹2Lake Murray-Edenwood 230kVline and Lake Munay230/115kY auto transf ¹1

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Lake Murra -Saiuda 115kv line

Saluda-McMeekin 115kv line

110

Exhibit No. (HCY-5)Page 10 of 19

Bush River-Parr 230kV line andSaluda-McMeekin 115kV line

Bush River-Parr 230kv line andLake Murra -Saluda 115kv line

Run ¹3- build emai the lu ia c

in Run ¹2, the Parr-Denny Terrace 230kV line and VC Summer-Lake Murray 230kV lineboth overload for n-2 contingencies in the Columbia area. The analyses in Run ¹2show that both of these lines will require upgrading. Also, the overloading of theupgraded Parr-Denny Terrace 230kV line shows that a second Parr-Denny Terrace230kV circuit is needed. In Run ¹3 the alternative of constructing a Parr-Denny Terrace230kV line ¹2 with 81272 conductor and leaving the existing ¹1 line as 1272 conductoris evaluated. In addition, in Run ¹3 a 3" Lake Murray 230/115kV auto transformer isadded.

For Run ¹3, the following transmission modifications are made:

1. Upgrade the Parr-VC Summer 230kV line ¹1 to 81272 conductor.2. Upgrade the Parr-VC Summer 230kV line ¹2 to 81272 conductor.3. Add a new Denny Terrace-Lyles ¹2 230kV line (81272)4. Add a 3rd 230/115kV 336 MVA auto transformer at Lake Murray.5. Upgrade the VC Summer-Pineland 230kV line to 81272 conductor.6. Upgrade the VC Summer-Denny Terrace 230kV line to 81272 conductor.7. Upgrade the Parr-Denny Terrace 230kV line to 812726. Upgrade the VC Summer-Lake Murray 230kV line to 81272

There are no overloaded facilities in the Run ¹3 base case (no outages).

Them are no ovehoaded facilities in the Run ¹3 n-1 analyses due to the additionalgeneration.

Sel d N-2 ConditionsThe Run ¹3 n-2 analyses show the following overload conditions due to the additionalgeneration:

10

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L les 230/115kv auto transf 336 110

Exhib it No. (HCY-5)Page 11 of 19

Denny Terrace 230/115kV autotransf ¹1 and Denny Terrace230/1 15kv auto transf ¹2

Denny Tenace-Lyles 230kV ¹1line

Denny Tenace 230/115kv autotransf ¹1

Denny Tenace 23N115kV autotransf ¹1

Denny Terrace 230/115kv autotransf ¹2

Denny Terrace 230/115kv autotransf ¹2

Lake Muira -Saluda 115kv line

Lake Murra elude 115kv line

Lake Murra aluda 115kv line

Saluda-McMeeldn 115kv Ine

Saluda-McMeekin 115kv line

Salade-McMeekin 115kv line

510

255

255

255

119

110

117

105

101

118

Denny Terrace-Lyles 230kv ¹2line and VC Summer-DennyTerrace 230kv hne

Lyles 230/1 15kv auto transf andDenny Terrace 230/115kV autotransf ¹2VC Summer-lake Murray230kV line and Denny Terrace23$115kv auto transf ¹2Lyles 230/1 15kv auto transf andDenny Terrace 23N115kv autotransf ¹1VC Summer-Lake Murray230kv line and Denny Terrace23N115kV auto transf ¹1Bush River-Parr 230kV line andSaluda-McMeekin 115kV lineLyles-Williams St 115kv lineand Salads-McMcskin 115kVlineLake Murray-Edenwccd 230kvline and Salads-McMeekin115kV line

Lake Murray~tuda 115kv line.and Bush River-Parr 230kV lineLake Murray~ludo 115kV lineand Lyles-William Street 115kvlineLake Murray-Saluda 115kv lineand Lake Murray-Edenwood230kv line

un ¹4- Add two new lines servin e Columbia load center

Run ¹3 shows that upgrading all four 230kV lines from the VC Summer area to theColumbia Area load center along with several other transmission improvements isrequired to accommodate the additional VC Summer generation. However, upgradingthese lines to B1272 will require the removal of the existing facilities resulting in the lossof the transmission capacity associated with these existing lines. Removal of thesefacilities and replacing them with new construction has the net effect of receiving only50% of the capability of the new transmission improvements. Doing this even thoughthere is significant capability and life remaining in the existing lines is not a cost effectivepractice.

In Run ¹4 we will evaluate adding a new VC Summer-Killian 230kV line and a new VCSummer-Lake Munay 230kV line.

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Exhibit No (HCY-5)Page 12 of 19

Also, for Run ¹4 only one 230kV B1272 circuit between Lyles and Denny Terrace isconsidered.

For Run ¹4, the following transmission modifications are made:

1. Upgrade the Parr-VC Summer 230kV line ¹1 to B1272 conductor.2. Upgrade the Parr-VC Summer 230kV line ¹2 to B1272 conductor.3. Upgrade the Denny Terrace-Lyles 230kV line to 81272 conductor.4. Add a 3rd 230/115kV 335 MVA auto transformer at Lake Murray.5. Add a VC Summer-Killian 230kV line with B1272 conductor6. Add a VC Summer-Lake Murray 230kV ¹2 line with B1272 conductor

Base Case ConditionsThere are no overloaded facilities in the Run ¹4 base case (no outages).

~N-1 o dihonsThe Run ¹4 n-1 analyses show the following overload conditions due to the additionalgeneration:

N-2 ConditionsThe n-2 analyses show the following overload condiUons due to the additionalgeneration:

Overloaded Facility

Denny Terrace 230/115kV autotransf ¹1

Denny Terrace 230/115kv autotransf ¹2

EmergencyRahngMVA

336

Overload Contingency(si

115'enny Terrace 230/115kV autotransf ¹2 snd Denny Terrace-L les 230kv line

Denny Terrace 230/115kv autotransf ¹1 and Denny Terrace-

114 L krs 230kv line

Lake Murra luda 115kv line

Lake Munay-McMeekin 115kvline

Saluda-McMeekin 115kv line

255

255

106-126

104-111

101-127

Saluda-McMeekin 115kV line orLake Murray-McMeekin 115kvline and one of various otherColumbia Area transmissionfacirrsesLake Murray&sleds 115kv lineor Salade McMsekin 115kV lineand one of various otherColumbia Area transmissionfacilitiesLake Murray-Saluda 115kV lineor Lake Murray-McMeekin115kv line and one of variousother Columbia Areatransmission facilities

12

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Exhibit No. (HCY-5)Page13 of19

un ¹5 -Add two new I nes servi C Iumb load ce a additionaltrans ission im vements

In Run ¹4, the loss of the Denny Terrace-Lyles 230kV line and one of the DennyTerrace 230/115kV auto transformers results in the remaining Denny Terrace230/115kV auto transformer overloading. Adding a 3" Denny Terrace 230/115kV autotransformer will correct this problem.

Also, upgrading the Lake Murray-Saluda 115kV line, the Lake Murray-McMeekin 115kVline and the Saluda-McMeekin 115kV line to 81272 conductor will eliminate theoverloads on those lines.

For Run ¹5, the following transmission modifications are made:

1. Upgrade the Parr-VC Summer 230kV line ¹1 to 812722. Upgrade the Parr-VC Summer 230kV line ¹2 to 812723. Upgrade the Denny Terrace-Lyles 230kV line to 812724. Add a 3~ 230/115kV 336 MVA auto transformer at Lake Murray5. Add a 3" 230/115kV 336 MVA auto transformer at Denny Terrace6. Add a VC Summer-Killian 230kV line with 812727, Add a VC Summer-Lake Murray 230kV line ¹2 with 812726. Upgrade the existing Ssluda-McMeekin 115kV line with 812729. Upgrade the existing Lake Murray-McMeekin 115kV line with 8127210. Upgrade the existing Lake Murray-Saluda 115kV line with 81272

There are no overloaded facilities in the Run ¹5 base case (nooutages).'N-

ChNons

There are no overloaded facilities in the Run ¹5 n-1 analyses due to the additionalgeneration.

Selected N-2 ConditionsThere are no overloaded facilities in the Run ¹5 n-2 analyses due to the additionalgeneration.

13

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B. Short Circuit Analysis

Exhibit No. (HCY-5)Page 14 of19

An initial review of the effect of the increased fault current in the VC Summer area dueto the new generation and the required transmission facilities indicates that sixteen230kV breakers (eleven at VC Summer and five at Parr) are projected to beoverstressed. Additionally, nine 115kV breakers in the Columbia area are projected tobecome overstressed. Each of these overstressed breakers will need to be replacedwith a higher capacity breaker.

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III. Pre liming Recommendattons

Exhibit No. (HCY-5)Page 15 of 19

osedTrans isso

The analyses peiforrned in this study show that constructing two new 230kV tines fromthe proposed VCS ¹2 generator to the Columbia Area load center, plus additionaltransmission improvements descnbed below, ars required to reliably transmit the 1,165MW of the proposed VC Summer ¹2 generator from of the VC Summer area to theremainder of the SCE&G system. Also, the analyses show that constructing two new230kV lines is less costly and more effective than upgrading the numerous exisfing230kV transmission facilities that currently transmit power from the VC Summer area.

The required transmission projects are:

1. Construct a new VC Summer-Killian 230kV line with 81272 conductor~ (add 230kV terminal at Killian)

2. Construct a new VC Summer-Lake Murray 230kV line with 81272 conductor~ (add 230kV terminal at Lake Murray)

3. Construct a new VC Summer-VC Summer (exisbng) Bus ¹2 230kV line with81272 conductor

~ (add 230kV terminal at existing VC Summer Bus ¹2)4. Construct a new VC Summer-VC Summer (existing) Bus ¹3 230kV line with

81272 conductor~ (add 230kV terminal at existing VC Summer Bus ¹3)

5. Upgrade the existing Denny Terrace-Lyies 230kV line to 812726. Upgrade the existing Parr-VC Summer ¹1 230kV line to 812727. Upgrade the existing Parr-VC Summer ¹2 230kV line to 812726. Add a 3rd 230/115kV 336 MVA auto transformer at Lake Murray9. Add a 3rd 230/115kV 336 MVA auto transformer at Denny Terrace10. Upgrade the existing Saluda-McMeekin 115kV line to 8127211. Upgrade the existing Lake Murray-McMeekin 115kV line to 8127212. Upgrade the exisbng Lake Murray&aluda 115kV to with 81272

Construct a new 230kV generator substation at the proposed sits using a breaker-and-s-half design with seven 230kV terminals.

1. One - for the generator step up transformer2. One - for station service3. One - for the nsw 230kV line to the existing V. C. Summer 230kV bus ¹24. One -for the new 230kV line to the existing V. C. Summer 230kV bus ¹35. One - for the new 230kV line to Lake Murray6. One - for the new 230kV line to Killian7. One-forthe nsw230kV line to Santee Cooper

A total of eleven 230kV breakers are needed at the new generator substation for thisdesign.

15

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Exhibit No. (HCY-5). P ge16 of 19

To resolve overstressed conditions of several 230kV and 115kV breakers as describe8in the Short Circuit Analysis section, Transmission Planning recommends replacing thefollowing breakers with higher interrupting capability breakers:

Location Voi e Breaker SVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC SummerVC Summer

230230230230230230230230230230230

87228732874287728792883288428852889289128942

ParrParrParrParrParr

230 6402230 6412230 6422230 6432230 6442

Saiuda H ro 115 562McMeekinMcMeekinEdenwoodEdenwoodEdenwoodDenny TerraceDenny TerraceDorm Tenace

115 1051115 2051115 2712115 3672115 3682115 8032115 8042115 8092

16

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Exhibit No. (HCY-5)Page 17 of 19

IV. General E ineerin Desi n

Sin le Line Dla ramRed — New installationsBlue — Existing facilitiesGreen — Upgraded facilities

to San(co

Lake Morr

17

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SubstaSon Sin le Line

Exhibit No. (HCY-5)Page 18 of19

18

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V. Cost Estimates

All cost estimates are in 2014 dollars.

Exhibit No. (HCY-5)Page 19 of 19

1. Construct VC Summer-Killian 230kV.. . $25,000,000~ (add 230kV terminal St Killian) .. 1,100,000

2. Construct VC Summer-Lake Murray 230kV........................, ...............17,000,000~ (add 230kV terminal at Lake Murray) ...................................1,100,000

3. Construct new VC Summer-VC Summer (existing) Bus ¹2 V .................600,000~ (add 230kV terminal at existing YC Summer Bus ¹2)...........1,100,000

4. Construct new VC Summer-VC Summer (existing) Bus ¹3.....................600,000~ (add 230kV terminal at existing VC Summer Bus ¹3)..........,1,100,000

5. Upgrade existing Denny Terrace-Lyles 230kV ....................................:1,500,0006. Upgrade existing Parr-VC Summer¹1 230kV......................................1,400,0007. Upgrade existing Parr-VC Summer¹2230kV......................................1,400,0008. Add a 3rd 230/115kV 336 MVA auto transformer at Lake Murray ........5,000,0009. Add s 3rd 230/115kV 336 MVA auto transformer at Denny Terrace ....8,000,00010. Upgrade existing Saluda-McMeekin 115kV line ......................................125,00011. Upgrade existing Lake Murray-McMeekin 115kV line..............................500,00012. Upgrade existing Lake Murray-Saluda 115kV .........................................450,000

Construct a new 230kV generator substation at the proposed siteusing a breaker-and-a-half design with seven 230kV terminals ..............12,950,000

Replace overstressed1. 230kV breakers-162. 115kVbreskers-9.

. 3,200,000

.1,350,000

Total Cost Estimate. . 883,478,000

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x I I o.Page 1 of 18

A SCANA COMPANY

Generator Interconnection Feasibility StudyFor

SCE8G V.C. Summer Nuclear ¹3Version ¹2

Prepared for:SCE8G Nuclear Group

December 18, 2006

Prepared by:SCE&G Transmission Planning

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Exhibit No. (HCY-6)Page 2 of 18

TABLE OF CONTENTS

General Discussion..

I. Generator Information.

Page 3

Page 4

II. Transmission Studiesa. Power Flow Analysis.b. Short Circuit Analysis .....

Page 5. Page 12

III. Preliminary Recommendations .....

IV. General Engineering Design

V. Cost Estimates

. Page 14

. Page 16

Page 18

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Exhibit No. (HCY-6)Page 3 of 18

Generator interconnection Feasibility Study forSCE&G V.C. Summer Nuclear ¹2

Generator Interconnection Feasibili Studies are Intended to be preliminary studies toaid the requestorin determining if the application should advanced to additional, moredetailed and more costly studies or be withdrawn. These additional studies include theSystem Impact Study, Optional Upgrade Studies and the Facility Study. InterconnectionFeasibility Studies do not determine the final facilities and costs ofinterconnecting therequested generator to the existing transmission system.

General Discussion

SCE&G Transmission Planning conducted an initial Generator InterconnectionFeasibility Study for V.C. Summer ¹3 (report dated October 3, 2006) assumingSCE&G would own the entire power output of this unit. Subsequent to releasingthe initial report, Transmission Planning was informed that Santee Cooper willown 45% of the V.C. Summer ¹3 unit, also. This report presents the results of astudyincluding this information.

The SCE&G Nuclear Group has applied for interconnection of a new 1375 MVA nucleargenerator near the existing V.C. Summer site. This new generator would be the thirdnuclear unit at the V.C. Summer site. This new generator would be jointly owned bySCE&G and Santee Cooper, SCE&G would own 55% and Santee Cooper would ownthe remaining 45%. In this study SCE&G simulated Santee Cooper's portion of thegenerator being delivered to the Santee Cooper system.

This study assumes the V.C. Summer ¹2 unit is complete and all associatedtransmission as described in the Generator Interconnection Feasibility Study report forV.C. Summer ¹2 is in-place.

The format of the report is as follows:

I. Generator Information (provided by the SCE&G Nuclear Group)II. Transmission Studies

A. Power Flow AnalysisB. Short Circuit Analysis

III. Preliminary RecommendationsIV. General Engineering DesignV. Cost Estimates

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Exhibit No. (HCY-6)Page 4 of 18

I. Generator Information

The generator design consists of a single nuclear unit and one step-up transformer.The generator unit will have a maximum gross MVA output capacity of 1,375 MVA anda maximum net MW of 1,165 MW.

The generator design consists of the following information:MVA — gross: 1375MW- net: 1165Power Factor: between .90 and 1.05Voltage: 22IRV

Speed: 1600 rpmX'd-sat.: 0.465 PU; X"d-sat.: 0.325 PUX2-sat.: 0.320 PU; XO: 0.237 PU

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Exhibit No. (HCY-6)Page 5 of 18

II. Transmission Studies

A. Power Flow Analysis

For the proposed generator interconnection of the VC Summer ¹3 generator,Transmission Planning performed analyses of:

1. Base case conditions (no outages) simulating normal conditions2. N-1 conditions simulating single facility outages of each transmission facility on

the SCE&G system3. Selected n-2 conditions simulating the loss of two facilities on the SCE&G

transmission system

This study is based on future projected conditions on the SCEBG transmission system,simulating 2016 peak summer conditions and assumes that the following transmissionimprovements will be made to SCE&G's Columbia and Charleston area transmissionsystem prior to 2016. These transmission improvements are currently scheduled andare needed for other system needs:

1. Upgrade Lyles-William Street 115kV line2. Upgrade William Street-Coit 115kV line3. Upgrade Lyles-Denny Terrace 115kV line ¹1 and ¹24. Add a 2"'ake Murray 230/115kV auto transformer5. Increase thermal rating on the Denny Terrace-Lyles 230kV line6. Upgrade Canadys-Church Creek 230kV line7. Add a Canadys-Pepperhill 230kV line (double circuit with Canady-Church Creek

230kV Upgrade)

As mentioned earlier, this study assumes the V.C. Summer ¹2 unit is complete andoperating and the following associated transmission projects are complete and in-

service:

1. VC Summer-Killian 230kV line2. VC Summer-Lake Murray 230kV line3. VC Summer (new)-VC Summer (existing) Bus ¹2 230kV line4. VC Summer (new)-VC Summer (existing) Bus ¹3 230kV line5. Upgrade the existing Denny Terrace-Lyles 230kV line6. Upgrade the existing Parr-VC Summer ¹1 230kV line7. Upgrade the existing Parr-VC Summer ¹2 230kV. line8. Add a 3rd 230/115kV 336 MVA auto transformer at Lake Murray9. Add a 3rd 230/115kV 336 MVA auto transformer at Denny Terrace10. Upgrade the existing Saluda-McMeekin 115kV line11. Upgrade the existing Lake Murray-McMeekin 115kV line12. Upgrade the existing Lake Murray-Saluda 115kV line

Additionally, this study assumes that the following proposed transmission modificationswill be made by Santee Cooper to their transmission system as part of theirinterconnection to the V.C. Summer ¹2 generator. These transmission improvementswere provided by Santee Cooper:

5

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Exhibit No. (HCY-6)Page 6 of 18

1. Add a VCS-Winnsboro 230kV line with 230/69kV transformers at Winnsboro.2. Add a Winnsboro-Richburg 230kV line with 230/69kV transformers at Richburg.3. Add a Richburg-Flat Creek 230kV line

Furthermore, this study assumes that the following proposed transmission modificationswill be made by Santee Cooper to their transmission system as part of theirinterconnection to the V.C. Summer ¹3 generator. These transmission improvementswere provided by Santee Cooper:

1. Add a VCS-Sandy Run 230kV line with a 230/115kV transformer at Sandy Run2. Add a Sandy Run-Orangeburg 230kV line with a 230/115kV transformer at

Orangeburg3. Add an Orangeburg-St. George 230kV line with a 230/115kV transformer at St.

George.4. Add a St. George-Varnville 230kV line

Run ¹1 — In ection of the ro osed1 165 MWat the new VC Summer 230kVwithno affiliated transmission im rovementa

For the initial analysis, an additions! 1,165 MW!s injected at the new VC Summer230kV bus with no affiliated modifications to the SCE&G transmission system. With theexisting VC Summer net generation of 966 MW, the Fairfield Pumped Storage netgeneration of 608 MW, the proposed VC Summer ¹2 net generation of 1,165 and thenew proposed VC Summer ¹3 net generation of 1,165, the total net MW generationconnected to the 230kV system in the vicinity of the VC Summer site is 3,904 MW.

Base Case ConditionsThere are no overloaded facilities in the base case (no outages). However, severalexisting 230kV lines in the VC Summer area are loaded above 50% of their NormalRating:

~ The VCS¹1 bus ¹1-Pineland 230kV line loads to 58% of its 475 MVA NormalRating

~ The VCS¹1 bus ¹1-Denny Terrace 230kV line loads to 56% of its 475 MVA

Normal Rating~ The VCS¹1 bus ¹1-Blythewood (Santee Cooper) 230kV line loads to 77% of its

478 MVA Normal Rating~ The VCS¹1 bus ¹3-Lake Murray 230kV line loads to 52% of its 704 MVA Normal

Ratingo The VCS¹1 bus ¹3-VCS New 230kV line loads to 53% of its 950 MVA Normal

Rating~ The VCS¹1 bus ¹2-VCS New 230kV line loads to 53% of its 950 MVA Normal

Rating~ The Parr-Denny Terrace 230kV line loads to 64% of its 704 MVA Normal Rating~ The Parr-Bush River (Duke) 230kV line loads to 52% of its 456 MVA Normal

Rating

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Exhibit No. (HCY-6)Page 7 of18

~ The Lake Murray-Edenwood 230kV line loads to 59% of its 475 MVA NormalRating

N-1 ConditionsThe n-1 analyses show the following overload conditions due to the additionalgeneration:

Selected N-2 ConditionsThe n-2 analyses show the following overload conditions due to the additionalgeneration:

Overloaded FaciliRatingMVA

Loading%%uo Contin enc s

Lake Murray 230/115kV autotransformer ¹1

Lake Murray 230/1 15kV autotransformer ¹2

Lake Murray 230/115kV autotransformer ¹3

336 110

336 110

336 110

Lake Murray 230/115kV autotransformer ¹2 and Lake Murray230/115kV auto transformer ¹3Lake Murray 230/115kV autotransformer ¹1 and Lake Murray230/1 15kV auto transformer ¹3Lake Murray 230/115kV autotransformer ¹1 and Lake Murray230/115kV auto transformer ¹2

VC Summer ¹1 bus ¹3-VC SummerNew 230kV line

VC Summer ¹1 bus ¹2-VC SummerNew 230kV line

1020

1020

100-135

100-135

VC Summer ¹1 bus ¹2-VCSummer New 230kV line andvarious other Columbia Area 230and 115kV linesVC Summer ¹1 bus ¹3-VCSummer New 230kV line andvarious other Columbia Area 230and 115kV lines

Saluda-Geor ia Pacific 115kV line 95 108Parr-Bush River (Duke) 230kV lineand Saluda-White Rock 115kV line

Saluda-White Rock 115kV line

Saluda-White Rock 115kV line

95

95

133

114

Parr-Bush River (Duke) 230kV lineand Saluda-Georgia Pacific 115kVline

Parr-Bush River (Duke) 230kV lineand VC Summer-Pomaria (Santee)230kV line

Saluda-White Rock 115kV line 95 121

Parr-Bush River (Duke) 230kV lineand Parr-Newport (Duke) 230kVline

Saluda-White Rock 115kV line

Saluda-White Rock 115kV line 95 115

Parr-Bush River (Duke) 230kV lineand VC Summer-BlythewoodSantee 230kV line

Parr-Bush River (Duke) 230kV lineand VC Summer-Ward 230kV line

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Exhibit No. (HCY-6)Page 8 of 18

The n-2 analyses show the following highly loaded conditions due to the additionalgeneration:

Hi hl LoadedFacil'ating

MVA

Loading~k Contin enc s

L les-Edenwood 230kV line

VC Summer«1 bus ¹1-DennyTerrace 230kV lir,e

VC Summer ¹1 bus ¹1-BlythewoodSantee Coo er 230kV line

VC Summer ¹1 bus ¹1-Pineland230kV line

VC Summer ¹1 bus ¹3-Lake Murray230kV line

VC Summer New-Lake Murray230kV line

Wateree-Sumter (Progress) 230kVline

510

"10

550

510

755

1020

500

80

91

90

92

85

VC Summer ¹1 bus ¹3-LakeMurray 230kV line and VC SummerNew-Lake Murra 230kV line

Parr-Denny Terrace 230kV line andVC Summer ¹1 bus «1-Pineland230kV!ine

Wateree-Sumter (Progress) 230kVline and VC Summer-WinnsboroSantee Coo er 230kV line

Parr-Denny Terrace 230kV line andVC Summer new-Killian 230kV line

Parr-Denny Terrace 230kV line andVC Summer New-Lake Murray230kV lineVC Summer ¹1 bus ¹3-VCSummer New 230kV line and VCSummer ¹1 bus ¹2-VC SummerNew 230kV lineWateree-Orangeburg 230kV lineand Wateree-Summerville 230kVline

Run ¹2 — Create new aths from VC Summer to Charleston Load Center

In Run ¹1, four of the six major 230kV lines from the VC Summer Area to the ColumbiaLoad Center are highly loaded for an outage of two of the four remaining lines.Upgrades would be needed on at least two of the four lines to address these overloadsor additional new 230kV lines from the VC Summer Area to the Columbia Load Centerwould be needed.

Also in Run ¹1, the two 230kV lines leaving the VC Summer New 230kV substation tothe existing VC Summer Substation, each overload for the outage of the other. To

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Exhibit No. (HCY-6)Page 9 oflg

address this, we will evaluate adding a 3" 230kV line from VC Summer New 230kVsubstation to the existing VC Summer Substation bus ¹1 with B1272 conductor.

We also have two major 230kV tie lines that are highly loaded. The 230kV lines are theWateree-Sumter (Progress) 230kV line (a transmission tie with Progress Energy) andthe VC Summer ¹1-Blythewood (Santee Cooper) 230kV line (a transmission tie withSantee Cooper). The high loading on these two lines shows that the generation istrying to leave the Columbia area or, in other words, the generation in the Columbiaarea needs another path to a major load center.

In Transmission Planning's 2016 system model, the Columbia area has a projected loadof 2,110 MW. In that same year, including the VC Summer ¹3 1,165 MW generator,there is a total of 5,772 MW of generation located in the Columbia area with 3,793 MWowned by SCE&G and the remainder owned by Santee Cooper (their ownership portionof VC Summer ¹1, ¹2 and ¹3) and the Columbia Energy Center. Just in the VCSuinmer area, there is a total of 3,904 MW of generation with 2,534 MW belonging toSCE&G.

In Transmission Planning's 2016 system model, the Charleston area has a projectedload of 1,960 MW. However, there is only 657 MWof SCE&G generation located in theCharleston area.

All of this information shows that there will be significant generation excess in theColumbia area while there is significant generation deficit in the Charleston area, asindicated in the table below.

Total Load (MW)Columbia Area 2,110Charleston Area 1,960

Year 2016 Projected Load and Generation LevelsTotal SCE&G

Generation (MW)4,317857

Difference (MW)2,207 (excess)-1,103 (deficit)

The generation deficit in the Charleston area is of concern to Transmission Planning,especially when contingencies are considered. A large portion of the generation in theCharleston area is the AM Williams unit (615 MW). When this unit is outaged theremaining SCE&G generation in the Charleston area is 242 MW creating a generationdeficit of-1,716 MW in the Charleston area. To address this concern, the followinganalysis will evaluate the effectiveness of new 230kV lines from VC Summer toward theCharleston Load Center.

Power flow simulations show two 230kV circuits will be required to carry an adequateportion of the 1,165 MW being studied away from the VC Summer Generation Site.Adding a total of two new 230kV circuits will carry approximately 300 MW out of the VCSummer area to the Charleston load center during normal conditions.

For Run ¹2, the following transmission modifications are made:

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Exhibit No. (HCY-6)Page 10 of 18

1. Establish a St George 230kV Switching Station with six line terminals. Fold in

the existing Wateree-Summerville 230kV line and the existing Canadys-Santee230kV line at St George.

2. Add a VC Summer New-St George 230kV line ¹1 and ¹2 (double circuit) withB1272 conductor

The additional 230 and115kV overloaded facilities that were identified in Run ¹1 will beaddressed, if needed, in subsequent runs.

Base Case ConditionsThere are no overloaded facilities in the base case (no outages).

N-1 Conditions

Selected N-2 ConditionsThe n-2 analyses show the following overload conditions due to the additionalgeneration:

Overloaded FaciliRatingMVA

Loading9o Contin enc s

Saluda-Geor ia Pacific 115kV line

Saluda-White Rock 115kV line

Saluda-White Rock 115kV line

95 104

95 128

95 116

Parr-Bush River (Duke) 230kV lineand Saluda-White Rock 115kV line

Parr-Bush River (Duke) 230kV lineand Saluda-Georgia Pacific 115kVlineParr-Bush River (Duke) 230kV lineand Parr-Newport (Duke) 230kVline

Saluda-White Rock 115kV line

Saluda-White Rock 115kV line

Saluda-White Rock 115kV line

95

95

95

112

113

108-113

Parr-Bush River 230kV line and VCSummer ¹1 bus ¹1-Blythewood230kV lineParr-Bush River 230kV line and VCSummer ¹1 bus ¹2-Ward 230kVline

Parr-Bush River 230kV line andone of various other 230 and115kV lines in the Cola area

Lake Murray 230/115kV autotransformer ¹1

Lake Murray 230/115kV autotransformer ¹2

Lake Murray 230/115kV autotransformer ¹3

336 106

336 106

336 106

Lake Murray 230/115kV autotransformer ¹2 and Lake Murray230/115kV auto transformer ¹3Lake Murray 230/115kV autotransformer ¹1 and Lake Murray230/115kV auto transformer ¹3Lake Murray 230/115kV autotransformer ¹1 and Lake Murray230/1 15kV auto transformer ¹2

10

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Exhibit No. (HCY-6)Page 11 of 18

The n-2 analyses show the following highly loaded conditions due to the additionalgeneration:

Hi hl Loaded Faciti

StGeor ~anad 230kV line

RatingMVA

377

Loading~k Contin enc s

87AM Williams Generation and StGeor e-Summerville 230kv line

St Geor e-Summerville 230kV line

St Geor e-Summerville 230kV line

St Geor e-Summerville 230kV line

St Geor e-Summerville 230kV line

VC Summer ¹1 bus ¹1-BlythewoodSantee Coo er 230kV line

VC Summer ¹1 bus ¹1-Pineland230kV line

VC Summer ¹1 bus ¹3-LakeMurra 230kV line

377

377

377

377

550

510

755

91

92

85

87

83

83

AM Williams Generation andCaned -Church Creek 230kv line

AM Williams Generation andCanady-Pepperhiil 230kV fine orGonad s-St. Geor e 230kV

line'anadys-Pepperhill 230kV lineand Canadys-Church Creek 230kVline

AM Williams Generation andCans -Williams 230kV line

Wateree-Sumter (Progress) 230kVline and VC Summer-WinnsboroSantee Coo er 230kV line

Parr-Denny Terrace 230kV lineand VC Summer New-Killian230kV line

Parr-Denny Terrace 230kV lineand VC Summer New-LakeMurrs 230kV line

Run ¹3 - Correct Overloaded and Hi hl Loaded Facilities

In Run ¹2, the additional generation along with the transmission modifications made toaccommodate the generation result in some overloaded and highly loaded lines in theSt George and Charleston areas. Also, some Columbia facilities are still showing asoverloaded. These will be addressed in this run.

For Run ¹3, the following transmission modifications are made:

1. Construct a VC Summer New-VC Summer ¹1 bus ¹1 230kV line with B1272conductor

2. Upgrade the St. George-Summerville 230kV line to B1272

ii

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3. Upgrade the St. George-Canadys 230kV line to B12724. Upgrade the Saluda-White Rock 115kV line to 12725. Upgrade the Saluda-Georgia Pacific 115kV line to 1272

Exhibit No. (HCY-6)Page 12 of 18

Base Case Condit'sThere are no overloaded facilities in the base case (no outages).

N-1 ConditionsThere are no overloaded facilities due to the additional generation.

Selected N-2 ConditionsThe n-2 analyses show the Lake Murray 230/115kV autotransformers continue tooverload for the loss of the other two autotransformers. This will be addressed byadding additional 230/115kV transformation in the Lexington area.

Because the (rC Summer ¹3 generator, along with the VC Summer ¹1 and ¹2 units, will

resultin significant nuclear generation on fhe SCE&G system with electrical poweroutputs thetis not expected to vary with changing load conditions, TransmissionPlanningis concerned about off peak system conditions. During light load systemconditions in 20f 6, the total amount of nuclear output on the SCE&G system canexceed the total amount of system load. As part of this study effort, light load, springpeak load and shoulder load (75% ofpeak) system conditions were reviewed. Thisreview showed that several system facilities overload during contingency conditions atoff-peak load conditions due to the expected unusual generation dispatch (all or mostlynuclear generation) and the fact that all this generationis locatedin one area.Transmission Planning will conduct a more thorough study of these conditions as part ofthe Generator Interconnection System Impact Study.

B. Short Circuit Analysis

An initial review of the effect of the increased fault current in the SCE&G area indicatesthat three 230kV breakers and eight 115kV breakers on the SCE&G transmissionsystem may become overstressed with the addition of the VC Summer ¹3 generatorand associated transmission improvements. These overstressed breakers would needto be replaced with higher capacity breakers.

The total short circuit contribution from the SCE&G Transmission System that will beseen at the VC Summer new Substation 230 kV bus is:

12

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Exhibit No. (HCY-6)Page13 of18

These values do not include the contribution of the VC Summer ¹3 generator. They doinclude the expanded SCELG Transmission System with projected improvements at thetime of interconnection and generation that is connected to the SCE8 G TransmissionSystem (including the proposed VC Summer ¹2 generator, the existing VC Summer ¹1generator and the Fairfield Pumped Storage Units). The values are calculated on a 100MVA base. A significant change is not expected in this equivalence for the next 10 to15 years, unless additional generation is interconnected in the area.'

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III. Prelimina Recommendations

Exhibit No. (HCY-6)Page 14 of 18

Pro osed Transmission Im rovements

The analyses performed in this study show that constructing two new 230kV lines fromthe proposed VC Summer ¹3 generator to the Charleston area load center, plusadditional transmission improvements described below, are required to reliably transmitthe SCE&G's ownership portion of the 1,165 MW of the proposed VC Summer ¹3generator from the VC Summer area to the remainder of the SCE&G system.

The required transmission projects are:

1. Construct VC Summer-St George 230kV Double Circuit B1272 line (135 miles)(Add 2 230kV terminals at VC Summer New)(breaker-and-a-half design)

2. Construct VCS New-VCS¹1, Bus ¹1(add 230kV terminal at existing VC Summer Bus ¹1)(breaker-and-a-half design)

3. Establish a St George 230kV Switching Station (breaker-and-a-half design)(6 terminals - 9 breakers)(Add land)

4. Fold-in the Canadys-Santee 230kV line at St George

5. Upgrade the Canadys-St George 230kV line to B1272(Upgrade Canadys terminal)

6. Fold-in the Wateree-Summerville 230kV line at St George

7. Upgrade the St George to Summerville 230kV line to B1272(Upgrade Summeiville terminal)

8. Upgrade Saluda-Georgia Pacific 115kV Double Circuit line to 1272(Upgrade Saluda terminal)

Add five (5) terminals (9 breakers) to the VC Summer New substation (breaker-and-a-half design).

1. One - for VC Summer ¹3 generator step up transformer2. One-for VC Summer¹3 station service3. One - for the new 230kV line to the existing VC Summer ¹1 230kV bus ¹14. Two-for the 2 new 230kV lines to St George

To resolve overstressed conditions of the breakers as described in the Short CircuitAnalysis section, Transmission Planning recommends replacing the following breakerswith higher interrupting capability breakers:

14

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Exhibit No. (HCY-6)Page 15 of 18

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Exhibit No. (HCY-6)Page 16 of 18

IV. General En ineerin Desi n

Sin le Line Die ram

B-I272

Sandy Run(SCPSA)

Grangebur(SCPSA)

To New(SCPSA)

Eshting )ICSTo Ward(SCEG)

Richburg(SCPSA)

Winnsboro(SCPSA)

~OFlat Creek(SCPSA)

St. Georg(SCPSA) Parr

(SCEG)

To Btythewood(SCPSA)

Vanvilh(SCPSA)

Lake Murray(SCEG)

DennyTerran(S ) Pineland

(SCEG)

Iolgan (SCEG)

Edenwoo(SCBG)

B.1272

To SRS(SCE&G)

Lyles(SCEG)

Canadys(SCE&G)

Cope(SCE&G)

B 1272

Watacc(SCEG)

To S antes(SCEfcG)

St Crcorgc(SCL&GI

t'old - In

Iet272

230k v Sisgie Line DiagramRed - New instsgationsBlue - Esisting facilniesGreen - Upgraded facilitiesPurple - Santee Cooper System

To Yemassee(SCE&G)

To Mateeba(SCPSA)

Summavilk(SCE&G)

Pepperhill (SCE&

Goose Creek(SCE&G)

AMW(SCE&G)

To Yemassee(SCE&G)

Faber Place(SCE&G)

Church Creek(SCE&G)

16

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Substation Sin le Line

Exhibit No. (HCY-6)Page 17 of 18

Bue - Es(sting systemRed - trcw CnnstructtnnGreen - Upgrmle

Gn(SCE&

(SCE&G) (gtgrsde8-1272

(SCE&G)

17

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V. Cost Estimates

Exhibit No. (HCY-6)Page 18 of 18

All cost estimates are in 2006 dollars.

1. Construct VC Summer New-St George 230kVDouble Circuit B1272 line (1 35 miles) ............ ..... $153,950,000

2...Construct VCS New-VCS¹1, Bus ¹1). .$600,000(add 230kV terminal at existing VC Summer ¹1 Bus ¹1 ) .............. $1,100,000

3. Construct St George 230kV Switching Station(Breaker-and-a-half design)

4. Fold-in the Canadys-Santee 230kV line at St George .....

$11,400,000

..... $ 1,100,000

5. Upgrade the Canadys-St George 230kV line to B1272 ......................$7,300,000

6. Fold-in the Wateree-Summerville 230kV line at St George ................$1,100,000

7. Upgrade the St George to Summerville 230kV line to B1272 .........., $ 15,300,000

8. Upgrade Saluda-Georgia Pacific 115kV Double Circuit line to 1272 $11,900,000

Expand the 230kV generator substation at the VCS New site ...

Replace overstressed1. 230kVbreakers-3.2. 115kVbreakers-8.

..... $ 12,000,000

.$600,000..$1,200,000

Total Cost Estimate $217,550,000

18

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Standard TpL-001-0 — System performance Under Normal Conditions Exhibit No. HCY-7Page 1 of 2

Table l. Transmission System Standards — Normal and Emergency Conditions

CategoryContingencies

Initiating Event(s) and ContingencyElement(s)

System Stableand both

Thermal andVoltage Limits

withinApplicable

Rating

'oss of Demandor

Curtailed FirmTransfers

System Limits or Impacts

CascadingOutages

ANo Contin encies

BEveni resulbng in tbeloss of a singleelement.

CEvent(s) resulting inthe loss of two ormore (multiple)elements.

All Facilities in Service

Single l.inc Ground (SLG) or 3-Phase (38) Fault, withNormal Clearing:

1. Geoerator2. Transmission Circuit3. Transformer

Loss of an Element without a Fault

eSingle Pole Block, Normal Clearing:

4. Single Pole (dc) Line

eSLG Fault, with Normal Clearing:

1. Bus Section

2, Breaker (failure or internal Fault)

SLG or 38 Fault, with Normal Cleaong, Manuale

System Adjustments, followed by another SLG or 38e

Fault, with Normal Clearing:3. Category B (B 1, B2, B3, or B4) contingency,

manual system adjustmeots, followed byaaother Category B (Bl, B2, B3, or B4)contin enc

Bipolar Block, with Normal Cleanng:e

4. Bipolar (dc) Line Fault (non 38), with Normale

Clearing .

5. Any two circuits of a multiple circuittowerline'LG

Fault, with Delayed Cleanng (stuck breaker orprotection system failure):

6. Generator

Yes

vesYcsYesYes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

No

No iNo iNoNo i

No

Planned/

Controlled'lanned/

Contmlled'lanned/

Controlled'laoned/

Controlled'lanned/

Controncsl'lanned/Coraroned'o

NoNoNoNo

No

No

No

No

No

L Transformer

S. Transmission Cncuit

Yes

Yes

Planned/

Controlled'lanned/

Controlled'o9. Bus Section Yes Planned/Controlled'o

Adopted by NERC Board of Trustees: February 0, 2005Effectiv Date: April 1, 2005

dof5

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Standard TPL-001-0 — System Performance Under Normal Conditions Eghjj)jt jsfo. Ht:Y-7Page 2 of 2

Extreme event resulting intwo or more (multiple)elements removed orCascading out of service.

1. Generator

2. Transmission Circuit

3. Trmsfonner

4. Bus Section

e313 Fault, with Normal Clearing:

5 Breaker (failure or internal Fault)

6. Loss of towerline with three or more circuits

7. AII transmission lines on a conunon rigbt-ofway

8. Loss of a substation (one voltage level plus transformers)

R Loss of a switching station (one voltage level plustransformers)

10. Loss of ail generatmg units at a station

11. Loss of a large Load or major Load center

12. Failure of a fully redundant Special Protection System (orremedial action scheme) to operate when required

13. Operation, partial operauon, or misoperation of a fullyreduadant Special Protection System (m Remedial ActionScheme) m response to an event or abnormal systemcondition for which it was not mtendul to operate

14. Impact of severe power swmgs or osmllations I'rom

Disturbances in another Regional Reliability Organization.

38 Fault, with Delayed Clearing (stuck breaker or protection systeme

failure):

Evaluate for risks andconsequences.

May mvolve subsuntial loss ofoustmner Demmd andgeneration in a widespreadarea or areas.

Portions or all of theinterconnected systems mayor may not achieve a new,stable operating point.

Evaluation of these events mayrequire Ioint studies withneighboring systems.

a) Applicable rating refers to the applicable Normal and Emergency facility thermal Rating or system voltage limit as determined andconsistently applied by the system or facility owner. Applicable Ratings may include Emergency Ratings applicable for shortdurations as required to permit operating steps necessary to maintain system control. All Ratings must be established consistentwith applicable NERC Reliability Standards addressing Facility Ratings.

b) Planned or controlled interruption of electric supply to radial customers or some local Network customers, connected to or suppliedby the Faulted element or by the affected area, may occur in certain areas without impacting the overall reliability of theinterconnected transmission systems. To prepare for the next contingency, system adjustments are permitted, includingcurtailments of contracted Firm (non-recallable reserved) electric power Transfers.

c) Depending on system design and expected system impacts, the controlled interruption of electric supply to customers (loadshedding), the planned removal from service ofcertain generators, and(or the curtailment of contracted Firm (non-recallablereserved) electric power Transfers may be necessary to maintain the overall reliability of the interconnected transmission systems.

d) A number of extrcme contingencies that are listed under Category D and judged to be critical by the transmission planningentity(ies) will bc selected for evaluation. It is not expected that all possible facility outages under each listed contingency ofCategory D will be evaluated.

e) Normal clearing is when the protection system operates as designed and thc Fault is clcarcd in the time normally expected withproper functioning of the installed protection systems. Delayed clearing ofa Fault is due to failure of any protection systemcomponent such as a relay, circuit breaker, or current transformer, and not because ofan intentional design delay.

I) System assessments may cxcludc thcsc events where multiple circuit towers are used over short distances (u.g., station entrance,river crossings) in accordance with Regional exemption criteria.

Adopted by NERC Board of Trustees: February 8, 2005Effective Date: April 1, 2005

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Exhibit No. (HCY-8)Page I of 1

SOUTH CAROLINA ELECTRIC & GAS COMPANY

LONG RANGE PLANNING CRITERIA

It is recognized that the reliability of power supply in local areas is the responsibility of theindividual systems and that each system has internal criteria relating to the more commoncontingencies. It is fiuther recognized that there are severe contingencies, which are credible, but ofa low probability of occunence, which may result in conditions such as islanding and/or loss ofload. Such condifions are considered acceptable as long as they are contmlled so as to limit theadverse impact of the disturbance and so as to leave the system or systems in such condition as topermit rapid load restoration and/or reconnection.

The requirements of the SCEd'rG "LONG RANGE PLANMNG CRITERIA" will be satisfied if thesystem is designed so that during any of the following contingencies, only short-time overloads, lowvoltages and local loss of load will occur and that after appropriate switching and re-dispatching, allnon-radial load can be served with reasonable voltages and that lines and transformers are operatingwithin acceptable limits.

a. Loss ofany bus and associated facilities operating at a voltage level of 115kV or above.

b. Loss ofany line operating at a voltage level of 115kV or above.

c. Loss ofentire generating capability in any one plant.

d. Loss ofall circuits on a common structure.

e. Loss ofany transmission transformer.

f. Loss ofany generating unit simultaneous with the loss of a single transmission line.

Outages more severe are considered acceptable if they will not cause equipment damage or resultin uncontrolled cascading outside the local area.