March 14, 20087Hawaiian Electric Company, Inc.

HECO System OverviewGeneration (Continued)

Jan DecSep

Total Installed Net Capacity

Predicted Peak Demand Minimum

Capacity Required

Available Reserve

Spinning Reserve capacity of the largest single unit

Unit Overhaul

Unit OverhaulUnit

OverhaulUnit

OverhaulUnit

Overhaul

Unit OverhaulMaint

Outage

Maint Outage

MaintOutage

MaintOutage

1672 MW

Illustration showing how the available reserve is used to plan and schedule generating unit outages.

Matthias Frippslides from http://www.heco.com/vcmcontent/GenerationBid/HECO/HECOSystemOverview.pdf and http://www.heco.com/vcmcontent/GenerationBid/HECO/CompetitiveBid/2011-12-07_Technical_Conference_Presentation.pdf

Matthias Fripp

March 14, 20088Hawaiian Electric Company, Inc.

2007 Actual Maintenance Schedule

HECO System Overview Generation (Continued)

0

50

100

150

200

250

300

350

400

1 31 61 91 121 151 181 211 241 271 301 331 361

Me g

a wa t

t s

Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec.Note: Months are set at 30 day periods. Theref ore the markers may not be set exactly according to the calendar y ear.

Reserve = Operating Capability (1698) - Largest Single Unit (180)- Predicted Peaks of 05/22/03

POWER SUPPLY OPERATION & MAINTENANCE 2007 PLANNED MAINTENANCE SCHEDULE

2007

Revision Date: 01/17/04

AES

KP L

P

H9

W6

KPLP

K6

W7

W8

H9 HRRV

K1

K5

K3

K4

H9

HRRV

H8

W5

W9

H9

W1 0

W9

W4

W3

K1

W3

W1 0

Note: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec Actual Peaks

K2

W8

W8K4

K1

K5

KPLP

HRRV

W3

W6

K4

K5

W9

W3

W3

K2

K6

K5

AES

W3

KPLP

AES

Revision Date: 1/18/08Reserve = Operating Capability (1698) Largest Single Unit (180) -Predicted Peaks of 5/23/07

March 14, 20089Hawaiian Electric Company, Inc.

Midnight Midnight

7 am 5 pm 9 pm

Peak Period

Shoulder PeakPriority Peak

Off-PeakOff-Peak

MW

HECO System Overview Generation (Continued)

Typical Daily System Demand (Load) Profile

Minimum Load

Peak Load

March 14, 200811Hawaiian Electric Company, Inc.

Illustration of meeting daily demand

12 midnight 6am 12 noon 6 pm 12 midnight

100

50

Cycling

Baseload

PeakingPeaking units such as W9 & 10 start up to meet the highest peak periods

Cycling units such as H8 & 9, W3-6 start up and shut down daily to support system peaks.

Baseload units such as K1-6, W7 & 8, AES, KPLP, HRRV, operate 24 x 7 and are dispatched up during peak periods and dispatched down to near minimum loads

HECO System Overview Generation (Continued)

March 14, 200812Hawaiian Electric Company, Inc.

Spinning Reserve and QLPU on a Daily Basis

12 midnight 6am 12 noon 6 pm 12 midnight

100

50

Cycling

Baseload

PeakingPeaking units typically operate at less than normal capacity to support SR and QLPU criteria

Selected cycling units operate less than normal capacity to support SR and QLPU criteria

Selected baseload units operate less than normal capacity to support SR and QLPU criteria

HECO System Overview Generation (Continued)

Minimum Spinning Reserve

March 14, 2008Hawaiian Electric Company, Inc.

Illustration of Spinning Reserve and Quick Load Pickup Operating Criteria

MW Output

Normal Capability Rating = 100 MW

Operating level serving load = 70 MW

Individual Unit Contribution to Spinning Reserve = 30 MW 3-Second Quick Load Pickup (QLPU) = 18 MW

QLPU provides a portion of the units spinning reserve within 3 seconds

HECO System OverviewGeneration (Continued)

100 MW Generating Unit

March 14, 200819Hawaiian Electric Company, Inc.

Automatic Generation Control (AGC)determines how many MW to increase or decrease on selected generators to correct for Time Error or minor Frequency Deviation from 60 Hz. AGC is capable of controlling frequency between 59.8 Hz and 60.2 Hz.

Economic Dispatch Calculation (EDC)determines what generators to use and which way the generators should move.

Energy Management System (EMS) translates the desired movement into up or down pulses and sends the pulses to the Turbine Control Systems of the selected generators.

The Turbine Control System moves the unit up or down in output in response to the EMS pulses.

AGC

EDC

0.2 sec pulse every 10 seconds to raise or lower generator output

VOLTAGE REGULATOR

EMS

EMS Raise/Lower

Pulses

Under normal conditions system frequency is regulated by the Energy Management System (EMS)

Energy Management System (EMS)

Raise/Lower Pulses

Frequency Regulation Normal Conditions(Continued)

March 14, 200823Hawaiian Electric Company, Inc.

Examples of what can trigger a disturbance:

Loss of generation due to protective trips (Supply < Demand)

Loss of transmission lines due to line faults (Supply > Demand)

Loss of a major substation transformer(Supply > Demand)

Loss of a large customer due to customer equipment malfunctions (Supply > Demand)

Impact of natural causes, i.e, storms, lightning, earthquake, tsunami, sea grass, jellyfish, etc.

March 14, 200825Hawaiian Electric Company, Inc.

Illustration of a Disturbance Caused by Loss of Generation

When a generator trips unexpectedly, a shortfall is created where the demand (load) is greater than supply and system frequency begins to sag to a value below 60 Hz. The rate of frequency sag (droop) depends on the size of the mismatch between Supply and Demand. As soon as underfrequency is detected, generation reserves are added via droop control till the frequency stops dropping. At this point the scale is still out of balance, but stable at a frequency below 60 Hz. To restore frequency back to the predisturbance level of 60 Hz, more generation from available spinning reserves is required.

(Supply < Demand)

6061

6258

59

System Underfrequency (Hz)

Load

(MW)

Generation

(MW)(Demand)

(Supply)

Pre-disturbance Generation

Generator Trip

Generation Reserve

Generation Overspeed ProtectionUnderfrequency Load Shedding

QLPU added to arrest the sudden drop-off in frequency

March 14, 200826Hawaiian Electric Company, Inc.

When load is lost unexpectedly due to transmission faults and other load related causes, a situation with excess generation is created that will cause system frequency to rise to a value above 60 Hz. As long as Supply > Demand, system frequency will continue to rise until all generators trip on overspeed. The rise in frequency can be arrested if generators are able to reduce their load before reaching their overspeed protection points.

(Supply > Demand)

6061

6258

59

System Overfrequency (Hz)

Load

(MW)

Generation

(MW)

(Demand)

(Supply)

Pre-disturbance Load

Underfrequency Load Shedding

Generator Load Reduction

Illustration of a Disturbance Caused by Loss of Load

Generation Reserve

Generation Overspeed Protection

December 7, 2011

Managing System Frequency Governor response

Hawaiian Electric generators use active droop with little or no dead band

Generation is normally controlled via AGC Frequency Control Economic Dispatch (normal condition)

Local Frequency Control (LFC) at each generating unit takes control of managing the system frequency during disturbances

Fast start generators Load management programs (CIDLC and RDLC) Manual & automatic under frequency load shedding Manual & automatic generator trip for excessive over

frequency 11

March 14, 200827Hawaiian Electric Company, Inc.

Abnormal Frequency Mitigation - Generation

Full range of operating frequencies

Generating Unit Turbine Control

Droop 5% continuous

Underfrequency:59.5 Hz to 59.8 Hz

Overfrequency: 60.2 Hz to 60.5 Hz

Generating UnitLocal Frequency Control (LFC)- 0.2 second pulse every 2 seconds outside of the control range

- 0.2 second pulse every 4 secondsinside the control range

59.8 Hz to 60.2 HzSystem Operation

Automatic Generation Control AGC)- 0.2 second pulse every 10 seconds

Control RangeLocationControl Device

December 7, 2011

Underfrequency Management 59.97 Hz Targeted Frequency Control Range Economic Dispatch. 59.97 Hz (1) AGC Off-Economic Frequency Regulation Control Modes. 59.90 Hz 59.80 Hz

Internal (Hawaiian Electric Dispatch) Frequency Alarm. External (Paging) Frequency Alarm Issued.

59.70 Hz RDLC Automatic UF Load Shedding. 59.50 Hz Hawaiian Electric Generators Switch To Local Frequency Control

Unit For Emergency Ramping. CIDLC Automatic UF Load Shedding.

58.50 Hz 58.00 Hz to 57.00 Hz

UF Auto Load Shed Kicker Block After 10-second delay. UF Automatic Load Shedding, No Delay. AES Trip at 58.2 Hz w/ 82 sec. time delay H-Power Trip at 58.0 Hz w/10 sec. time delay

57.00 Hz 56.50 Hz

Hawaiian Electric Generator Automatic Trip After 70-second delay. Hawaiian Electric Generator Automatic Trip, No Delay. Kahipa WF trip at 57.0 Hz w/ 6 sec. time delay Kalaeloa Trip at 56.8 Hz in 0.15 seconds

Notes: (1) Approximate, AGC switches based on Area Control Error (ACE) rather than

frequency. 13

December 7, 2011

Overfrequency Management 66.00 Hz (2) Hawaiian Electric Generator Automatic Overspeed Trip.

61.50 Hz (2) Hawaiian Electric Generator Overspeed Governors And Controls.

60.50 Hz Hawaiian Electric Generators Switch To Local Frequency Control Unit For Emergency Ramping.

60.20 Hz 60.10 Hz

External (Paging) Frequency Alarm Issued. Internal (Hawaiian Electric Dispatch) Frequency Alarm.

60.03 Hz (1) AGC Off-Economic Frequency Regulation Control Modes.

60.03 Hz Targeted Frequency Control Range Economic Dispatch.

Notes: (1) Approximate, AGC switches based on Area Control Error (ACE) rather than

frequency. (2) Approximate, similar but may differ by unit make and model.

12

March 14, 200830Hawaiian Electric Company, Inc.

Kahe 5 Droop Example

0 150

58

59

60

61

62F r

e qu e

n cy

( Hz )

Unit Output (MW)

Initial set-point at 75 MW, 5% droop

Generator MW output would slide back and forth along the 5% droop curve in an attempt to stabilize (match) supply and demand regardless of the frequency.

1005025 75 125

March 14, 200831Hawaiian Electric Company, Inc.

Underfrequency Load Shedding as a Mitigation Measure

December 7, 2011

Comparison of Existing and Proposed UFLS Schemes & NERC Limits

60 Hz

57 Hz

58 Hz

59 Hz

60 Hz

57 Hz

58 Hz

59 Hz

60 Hz

57 Hz

58 Hz

59 Hz

in 10 sec

in 5 & 10 sec

Floor

60 sec

Existing Scheme

Proposed Scheme

93MW

93MW

80MW

93MW 40MW

46MW 47MW

92MW

105MW

105MW

40MW

25MW

439MW

445MW

Freq. to remain above a log linear curve from 58 to

59.3 for 60 sec or until steady-state

above 59.3

NERC Design Parameters PRC-006-1

25% Gen. Loss

14

March 14, 200836Hawaiian Electric Company, Inc.

F re q

u en c

y ( H

z )

60 Hz

Time (sec.)

58.5

6 12

58.0

57.0

Block 1 trip

Block 2 trip

Kicker Block trip

2

Kicker Block timer initiated

Illustration of HECOs Underfrequency (UF)Load Shedding Scheme Design

March 14, 200832Hawaiian Electric Company, Inc.

Illustration of a Small versus Large Generating Unit Trip

System Frequency, Hz

60.0

58.5

10 sec time delay

Time, seconds

Smaller unit trip or more QLPU

Unit trip

Shed load

Assumes system frequency does not go below 58.0 Hz

Effects of a Small Unit Trip

Effects of a Large Unit Trip

March 14, 200834Hawaiian Electric Company, Inc.

System Frequency Based on Time of Day (24 Hour Clock)

System Frequency Based on Expanded Time Scale (33.5 seconds)

Actual example of a relatively large unit trip that did not result in load shedding (AES trip from 140 MW)

March 14, 200835Hawaiian Electric Company, Inc.

Frequency Response: AES, HRRV, K3 Gen Trip - 12/19/02(Waiau Site - Zoom)

57.00

57.50

58.00

58.50

59.00

59.50

60.00

1 35 0

4 8

1 37 7

8 5

1 40 5

2 2

1 43 2

5 9

1 45 9

9 6

1 48 7

3 3

1 51 4

7 0

1 54 2

0 7

1 56 9

4 4

1 59 6

8 1

1 62 4

1 8

1 65 1

5 5

1 67 8

9 2

1 70 6

2 9

1 73 3

6 6

1 76 1

0 3

1 78 8

4 0

1 81 5

7 7

1 84 3

1 4

1 87 0

5 1

1 89 7

8 8

1 92 5

2 5

1 95 2

6 2

1 97 9

9 9

Raw Data Count: approx 9 minutes elasped time

F re q

u en c

y ( H

z )

AES Trip

Kicker Block (58.5Hz)

Block 1 (58.0Hz)Block 2 (57.7Hz)

HRRV & K3 Trip

~10 seconds

Actual example of a relatively large unit trip that resulted inload shedding (AES trip from 180 MW)