diesel generator ieee paper 01601575

7/27/2019 Diesel Generator IEEE Paper 01601575

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General design criteria for diesel-generator sets for nuclear powerplants

This paper covers the design criteria for Diesel-Generators for Nuclear Power Plants. It deals with applicable

standards, loading, design performance, and characteristics to be considered in the selection of diesel-generator

set and its auxiliary system. This paper also discusses engineered safety features loads together with loss of

power safe shutdown loads and their starting sequence, analysis of voltage and frequency response and the diesel-

generator ability to start various load blocks successfully to meet the Reactor Emergency core cooling

requirements.Rangarao, G.Power Apparatus and Systems, IEEE Transactions on1358-1366July 1975

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IEEZ T r a n s a c t i o n s on Power A p p a r a t u s and Systems, vol. PAS-94, no. 4 , July/August 1975GENERAL DESIGN CRITER IA FOR DIESELGENERATOR SETS

FOR NUCLEAR POWER PLANTSGururajarao Rangarao

Ebasco Services IncorporatedNew York , N.Y.

ABSTRACTThis paper covers the design criteria for DieselG enerato n for

Nuclear Power Plants. It dealswith applicable standards, oading,design performance, and characteristics to be considered in theselection of diesel-generator set and its auxiliary system. This paperalso discusses engineered safety features loads together with loss ofpower safe shutdow n loads and their starting sequence, analysis ofvoltage and requenc y response and the diesel-generator ability tostart various load blocks successfully to meet the Reactor Emergencycore cooling requirements.

INTRODUCTIONDiesel-generators in nuclear powe r plan ts play a vital role as a

reliable wurce of standby ower to supply all safety features loads inthe event of loss of th e preferred off-site power concurr ent with lossof coolant accident and also be capable of- supplying norm al safeshutdown loads. Themost significant features to be considered inselecting a diesel-generator system are the fast-start andquick loadingcapabilities within maximumim eimit specified by reactormanu facturer and its perform ance reliability and confiden ce level'conforming to the AEC design criteria.Minimum Number of DieselG eneratorUnits for a

Nuclear Steam Supply SystemIn the main design of the nuclear steam supply system the

emergency core cooling system comprises of aminimum tworedundant cooling systems to avoid reactor core meltdown after aloss of coolan t accident (LOCA). Each redundant core coolingsystem is categorized as engineered safety features system also calledas engineered safeguard system requiring an independent standbypower source, which is supplied from the diesel-generator unitstarted automatically by a LOCA signal.

Modem nucleai pow er plants range in sizes 90 0 MW and above.Most PWR and HTGR eactors require two emergency core coolingsystems A BWR reactor is designed with three redundant c o o h gsystems, LPCS, LPCIandHPCS. Hence each PWR or H TGR NSSSrequires two diesel-generator systems whereas BWR NSSS requiresthree diesel-generators, one of which is specifically required asstandby power supply for the HPCS emergency core cooling system.

A multi-unit nuclear pow er station may share a diesel-generatorbetween tw o units to meet each of the following requirements:

Generation Committee of the IEEE Power Engineering Society for presentation atPaper T 74 5074 recommended and approved by the IEEE Powerthe 1974 Joint IEEE/ASME Power Generation Technical Conference, MiamiBeach, Ha., September 15-19, 1974.anuscript submitted May 16 , 1974;madeavailable fo r printing August 7,1974.

Dieselgenerator capacity mu st be sufficient to supply theengineered safety features loads upon LOCA on one unit,concu rrent with the safe shutdow n of the second unit.Dieselgeneratormust be capableof supplying standbypower as required in (a) above, with single failure on eitherunit engineered safety features systems not supplied by theshared diesel-generator.

Although the m inimum number of dieselgenerators required for atwo-unit nuclear power station may be three including the one withadequatecapacity aswell as capability to conform t o he aboverequirements (a) and (b), it is desirable to use two dieselgeneratorsfor each unit in a multiunit station. This latter arrangement willpermit comp lete separation between the redun dant engineered safetyfeature s systems in a multi-unit pow er station.Standards

Established stan dards and procedures in dieselge nerato r systemare governed by the following technical groups:AEC ANSI DEMAEMA OSHAANS ASME IEEE NEPA TEMA

Most standards and guides often used are the following for thedieselgenerator system:us AEC:us AEC:ANS:-ANSI:-ASME:-DEMA:4-E E E : ~NEMA:NEPA:OSHA:--TEMA :

Regulato ry Guides:' RG 1.9, RG 1.28, RG 1.29,RG 1.47 and RG 1.53Design Criteria 3, 17 and 1856.1, 56.12, 56.13, 56.14 and 56.15 (Reamtlyassigned numbers and 56.1 replaces 30.1)C1, C50.12,C50.13, C50.5, C57.12.00,C57.12.90, and C57.131 - Boiler and Pressure Vessel Code

Section In , Code Class 3, andSection VI11

2 - Power Test Code Number 17 for InternalCombustion Engines

1 - Standard Practices for Stationary Dieselan d Gas Engines

28-72, 11565, 279-71,308-74,323-14,324-71,32671 , 338-71 and 387-721 - M G I Standard Publication for Motors and

GeneratorsNational Fire Protection CodesFederal Occupational Safety and Health Admin-istration Standards, Parts 1581 and 1910Tubu lar Exchangers Standards

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Th e required capabilities of each diesel system are as follows:fast sta rting b) load accelerating c) load shedding d ) abilityto accept and carryoads upohe ratedapacitye) maintain frequency and voltage within specified limits.1. Continuousameplateating should exceed the

maximum load required at any time; this guaranteescontinuousoperationat a high availability greaterthan 95 percent capacity with an annual maintenanceinterval.

2. The contin uous rating of the diesel must be governedby he larger of the LOCA or normal shutdo wncondition.

The dieselge nerato r should be capable of reaching ratedspeed and voltage w ithin 10 seconds after receiving a signalto s tartrom remote unattendedutomaticontrolsystem. It shall also be capable of accepting full load fromthe tenth second w ithin the specified t i m e interval (usually1 0 +20 seconds).In addition to supplying rated emergency loads each dieselunit must be capable of supplying sufficientpower forbo th its mechanical and electrical auxiliaries.The diesel-generator should be capable of starting,acceleratingandsupplying oads in accordancewith thespecified loading sequence or restartand accelerate thelargest motor (load) after its tr ip ou t when the diesel wasfullyoaded. Themore stringent fither conditiongoverns in selecting the sizes.

The following AEC Regulatory requirements' will apply during1.The frequency dro p must be within 5 percent rom

the rated at any ime and recover to 98 percent ofnormal in less than 2 seconds.

2. The voltage dro p must be within 25 percent fro m therated voltage at its terminal and recover to 90 percentof normal in less than 2 seconds.

e )Th e speed of the diesel-generator does not exceed 115percent of nominal speed during recovery from thetransients caused by shedding the largest single load.

Standb y Auxiliary Power SystemFigure 1 represents Medium and Low Voltage emergency bus

systemAwith DieselGenerator No. 1connected to the MediumVoltage (MV) Bus A-1 This scheme indicates one of the wo standbypower systems, normal Medium Voltage Bus A with its conne ctionwithunit auxiliary and start-up ransformers. The combinationofloads on MV Bus A-1 and on LV Bus Al-1 makes up the load blockswhich are discussed in later part of the paper fo r dieselge nerators iz ing.

E Y R G E I K V L O I O S L . V. B U I A 1 . l ONE L INE DIAGRAM

Load StudyDiesel-generator hould be capable of supplying all ECCS oadsand supporting equip ment oads (i.e., battery charger, etc.) or the

load required fo r a normal safe shutdo wn -whic hever is larger.If the magnitude of the otal load is such that the generator

cannot accept it in onestep, t has to be sequenced so that hecoolant will always be available in the required quantity and on orbefore the required time limit.

T A B U L A T I O N IBWR (1100 Mwl PWR ( 9 0 0 MWlSAFE SHUmOWN

LOADTIMEOA DTIME LOAD *TIME LOAD *TILIELOCK LDC A SAFE SHUTDOI(NLOCA

NQ. WECONOLkW) WECOND)kWl && WECONDL -kW ) j SECONDI1 250 10 1700 10 200 10 560 102 1340 15 1340 15 500 13 800 133 ( 1 5 0 2 0 8 5 0 2 0 400 16 450 164 1300 25 4 6 6 2 5 500 19 500 19

H

5 & MANUALLYAPPLIED6

- 22 4 0 0 2 2

3 0 0 2 50 0 2 5

TIME FROM DIESEL STARTINGCHECK WHETHER LARGEST SINGLE LOAD TO RESTARTEXCEEW THE LAST LOADING STEP, IF SO ,THE LATTER WND~TIONWLL G OV ER N.

7 3% 28 3% 28-TOTAL 4230


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ACCIDENTLOSS OF QK)LAm(LOSP-LOCA)

z a

B W R

00w

TIME& SECONDSFIG. 2 LOAD STUDY (LOW-LOCA )

Tabulation I indicates the typical load data for BWR and FWRreactors and th e load stu dy is illustrated in Figures 2 an d 3.

LOSS OF OFF-SIT EPOWER ANDSAFE SHUT DOWN(LOW-SSD)

r0 I t ' I I I I0 5 1 0 1 5 2 0 2 5 ~

TIME -SECONDSFIG. 3 LOA D STUDY LO^ - ^ )

Generating Sizing:From he tabulation i t is evident that or loss of coolant

accident concu rrent w ith loss of off-site power, t he to tal emergencyload requirement is maximum. Hence the diesel unitcontinuousrating should have sufficient margin above thismaximum oad tomeet contingecies. For example in the above case selecting 4350 kWfor the BWR and 3250 kW for the PWR will provide an adeq uate sizefor the diesel-generator capacity.

It can be seen tha t the above load studies vary widely for thetype, size and design of each reactor. The load indicated in eachblock represents themotor loadsofpumps, ans, valves, contro lpanel feeds and any he ater feeds.Gen erator Capacity and Short-time Rating

All per unit (PU) uantities are in terms of generator capacity inkVA

LR C - locked rotor curren t in terms of full load curren t

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At an instant of the load block ISF = Full load curren tSs = Motor slip at starting = 1.0S = Motor slip under normal running condition (Slip

speed is expressed in percentage ofynchronousspeed)

r = Rot or resistance in ohmsX = Rot or reactance a t standstill

* Indicates the q uantities in complex num ber formlet RL =running load in kVA at Power Factor*

CO S8 1 -N 0.8*SL =starting load in kVA at Power Fact or

COS 82 E 0.2Gene rator capacity G c (nameplate rating) is:

( R L + S L ) -l o % 1 .1 ( R L + S L )100%* * * *with at least 10%margin andwhere the combined power factor for Gc = Cos 8

Gene rator Short-time capacity GSL is:

G i L =(R: + S L x LRCGE in PU ;

let

in PU

For an induction motorRotororqueRotornput zRoto r copper loss/slipdirect on line starting S= LRC; where a =xr

IC

We knowhat IGs&G*sL and largest is under resistivecondition. H ence genera tormanufacturer shall select generatorshort-time apacity qual to or exceeding s which will provideenough margin to take the i nrush of the largest starting loads. Theseshort-time ratings shall exceed the longest starting time of the biggestmotor on the medium voltage (MV) Bus. Also the trip setting timingof the m ot or overcurrent relay shall be provided with noughselective margin between themot or starting ime and gener atorshort-time rating for ocked roto r condition. This way we have aguarantee th at the diesel-generator can take the locked rotor curren tof the motor until the motor tripping time.Engine Sizing by Sequential Loading:5

b4

Let the emergency loads of DieselG enerato r be the induc tionmotors.

TR = Running load torque of the loads already connectedto the generator

For the starting motor letTS M = Maximum load torqueTS S = Startingoad torqueISS = Starting curren tTS F = Full load torque

Then the total torque with runniIig and starting loads

Let E T be he normal full load torque for all the emergency loadsunder normal running condition and TG is maximum torqueequivalent of generator capacity Gc

Then TG = 1.0 (PU) n base quantities

For any starting m otorTS S = T S F ( L R 0 2 S

L 2Sa J

-SM =TSM in (PU) =TSMTG

where TSF * Starting moto r in kVA-TG Gene rator capacity in kVA1361

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(ie any starting load can be expressed in percent or PU of generatorcapacity).

Let us s tudy thecase in which the largest motor is s t a r t e d whenall the rest of he emergencyoads are already onnected t ogenerator and ~ ~ i n gormal.Consid er the case. for th e largest motor let

T k = full load torqu eT; = starting torqu eT i = rest of th e loads unning torque = BT - T b

where BT = Normal full load torque for all the emergency loadsThen tota l torqueET)= T +T

=BT - T; +T;we know T i = Tk (LRQ2 SHence (ZT); = BT - T k +T (LRCI2 S

for starting torque conditionSimilarly for max imum torque con dition

Dividing by TG

1

= (starting load factor in Pv)where Mks = Motor constant for starting torque

= ( L R C ) ~MkM = Motor constant for maximum torque

= ~2 + a22sa

I IFrom Eq. 3 determine (CT)S and (XT)M and pick the largest torq ueand let it be = (BTf

By providin g t east 10percent excessmargin, the enginemaximum torque can be evaluated from the largest torqu e

From this torque, the engine maximum capacity in hp can bedetermined. The following tab ulation gives the moto r starting torqu econstan t for typical slip and locked rotor curren t capabilities.

I

LRC s% h$s (ZT)S MkM- - -- -- -4 1 a=0.23 0.91 0.819 1.82 3.41

5.5 4 1.21 1.119 1.45 2.605 1.51 1.419 1.25 2.136 1.82 1.729 1.13 1.823 1.08 0.989 1.82 3.41

6.0 4 1.44 1.349 1.45 2.605 1.80 1.709 1.25 2.136 2.16 2.069 1.13 1.823 1.27 1.179 1.82 3.41

6.5 4 1.69 1.599 1.45 2.605 2.11 2.019 1.25 2.136 2.54 2.449 1.13 1.82

Tabulation 2 Typical Motor Torque Constants(BT feva l u a t ed a t SLF = 1.0

a*. 1-1.7291.3591.1591.0391.7291.3591.1591.0391.7291.3591.1591.039

a 4 . 2-3.3 12.5092.0391.723.3192.5092.0391.723.3192.5092.0391.72

The above tabulation shows for typical mot or slips the mot ortorque constan ts and the maximum starting torq ue when the startingload f actor is 1.0 for starting torque and maximum torque condition.If the ratio a= is less than 0.2 he starting torque cond ition yieldsthe largest and it is better to design engine capacity with short-timemaximum rating.

r

Gene rator Subtransient Reactance:The generator subtransient reactance is mainly determined by

the maximum allowed voltage drop of 25 percent as established inth e design criteria:

To derive an expression for subtransient eactance for hediesel-generator le t us study model given below:

X xc x;;GENERATORDlESE L

STARTINGLOADEG MOTOR

RUNNINGLOADFig.6 Gene rator Load Schematic

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All the data given below is complete vector quantitiesXM = MotorubtransienteactanceXc = Cable reactance4 = Generator subtransienteactanceI = Currentt anynstantVG = Gene rator terminal voltageEG = Voltage behind genera tor reactanceIR = Running load current1s = Starting load curren tIG = Generator urrent when all emergency loads are runningnormalPM = Totalload in kVAG, = Gene rator capacity in kVAGS L = Generatorshort-time ating in kV A

I I

~ V GI G X ' ~1 = I R + I ~ -t an instantw h e n E G = 1.OPU

VG,= 0.75 PUI X G = 1 . 0- 0.75 = 0.25 PU

where I is expressed m PU of generator current

When IR +1s =the total load curre nt at th e load terminal voltage ofVM and let the total load is PM

$ = 0.25 (I: +.)0.25 Gc 'M'M "G

= (R L + SL x LRC)GC = GSL

where4 s expressed in PUUnder the worst situation of starting the largest mot or with the

rest of all the emergency load running in the diesel-generatorwhen GS L = G s L ( ~ ~ 1 ,s to be determined to meet thestandardperformancecharacteristic. GSL wax) an be evaluatedwhen RL =0 an d SL =0.909 LRC in PU.X; ; = 0.25 VM- (4)%L (Max) 'Gif VM/VG =0.95 (allowing 5 percent dr op across the cable)m en4=0.95 X 0.25 = 0.237

GS L (Max) GSL (Max)

Gene rator Symmetrical Short Circuit Level:Consider the following case:

a) Whole nuclear system is running normalb) Dieselg enerato r is connected parallel to the medium

voltage normal and emergency buses for testing purposesc) Dieselg enerato r is not supplying any load eith er to system

auxiliary or emergency loads.d) A fault occurs at the medium voltage normal system.

Using all the symbols in complexphasorquantities, the faultcontribution by DieselGenerator can be evaluated by the following:

From his derivation t is evident that he maximum faultcontrib ution is approximately four times the short-time rating of thedieselg enerato r, which is around 50 to 80 MVA symmetrical.

Thisdditionalault contrib ution ue to running paralleloperation of the diesel unit with system not only increases themedium voltage switchgear fa ult level but also imposes a restrictionto reduce the main generator and system fault contributionbyincreasing the unit auxiliary transformer reactance. This increase inthe transformer reactance inherently increases the voltage drop in th enormal buses under normal running condition.This situation isinherently bad for the low vo ltage mo tors and starters which in turnmay dr op out if the voltage of the bus is not up to the rated value.Therefore while rating the capacity of the medium voltage switchgearand sizing the unit auxiliary transformer eactance, it is better oinclude the fault contrib ution of the dieselgenera tor o get bettersystem condition.

By sizing the dieselge nerator reactance, the voltage drop can belimited within 25 percent whereas the recovery of the voltage within2 seconds is decided by the m otor starting current pattern and thequick response of the voltage regulator.Example:

The following are the load data HPCSDiesel Unit design:HPCS Motor Data (Typical)

Motor size =3000 hp , P F=0.85, Motor efficiency =0.88, Shaftefficiency= 0.8, Speed = 500 rpm, Slip = 4%, LR C =6.5, a = r h=0.1

Motor size = 3000 x 0*746 ; hp = 2nNs T F0.85 x 0.88 3 3000G ~ LM ~ )an be easily determined by the equa tion (1)

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Motor size = 3000 kV A = SL =0.85 PU

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HPCS motorcontrol center = 150 kVA = RL = 0.05 PUsizeTotal load = 3 1 5 0 k V A = 0 . 9P U

margin = 3 5 0 k V AD/G capacity = 3500 kVASL F = 3ooO = 0.8563500

= 1.69;MkM = (0.1)2 +(0.04)2 =1.452 x 0 . 1 o . 0 4For the argest torque condition(ST) = 0.909 + S u Mks - 1)(BT) = 0.909 + 0.8561.69 - 1.0) 1.4T F = 3500 x 33000 = 36.750 ft-lb2x 500*.T(S T) = 1.69 x 36.750 = 62,000D/c Max.capaci tywithexcessmargin 1056 = 62000 x 1.1 x2 x5OOXFiand shaft efficiency 3300 0 x 0.8

= 8 1 2 0 h pEnginerating = =Ox 1.1 = 48OOhp

0.8G, = 3500 kVA

GSL = 0.05 +0.85 x 6.5 = 5.58 PU (Max)GS L = 5.58 X 3500 = 19,550 kVADesigned zz 20 , 000kVA Ra ted for 20 seconds-SLX G = -I 0 2 3 7 5 = 0.2375 = 0.0425%L(Max) 5.58

ie . 4 .25%FD/G = 4.21 XGSL = 4.21 X 19,500 = 82,200 kVASymmetricalFrequency Variation637

Hi = Heat inp ut; JConversionactoreat in termsfmechanical un its

Heat input =(fuel oil lb/sec)x(heat rate Btuh b)2 = Efficiency

We = Work electrical; f =frequency in Hertz/=I = Inertia =I 1 (engine)'2 (fly wheel) +I3(gen erator)0 = Angular velocity (radians per second)G)' = ~n gu la r cce le ra tionI = W R q gg = 32.2t2/sec

(A )

WR2 = Moment of inertia in poudfeet '

Let all units are in ft-lbIH i T J =We + I d 3 (6 )

The problem to study is the change in speed during ttransients while loading or unloading the diesel-generator.

Hi? J - We3 r I a'Iunder normal running with constant load c3=0

whereN,/60ThenHi?J = We = ~ T Lwhere Ns = synchronous speed in rp m

(B) (given out ofenerator to loads)TL = Load Torque in ft-lbTR = RotationalTorqu e in ft-lb

25 7Ns TL = HiQJ60

(C) From Equatio n6) t any loading instant where W =W1 when furate is yet o change:

G ) 1 = H i ' l J - Y T L w 1 =dlI r3' where TR

(D) wheredl =5 here Nsl is speed when the60

Since thenum ber of the magnetic polesof the generator isbeing fixed, the change in engine speed determines the frequencyvariation under the following cases:

a) Speed change during start (from zero to the rated)b) When the load is con stan t, the speed stay stabilized.c) Change in loading cause the transients in speed by which

engine may accelerate or deceleratewithnertia andfueling rate.

In rdero study the speed changes let us consider thefollowing expression from heat balance.

Allowed Limitation of NS is 95 percent =0.95 N,1i e d 1 = 0.95 ddl= - 1 T L1

I 3'(3r1 H i? J d l T L ~ = H i P J - 0.95 d L ~

1 3 0.95 1 3From the E quation (6) when We = 0 during starting

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Parallel Oueration of Diesel Generator:herefore equation 8 can be rewritten in erms of tartingangular acceleration

d ' ( t rans ien t ) =3:/0.95 - T L ~ / I 1 . 0 5 2 g - T L ~ / I (9 )Once the acceleration rate for he criteria is designed suitable

fueling rate Hi and the response can be evaluated asgiven n thereference, by suitable governor.

H gh inertia during starting decreases the acceleration rate bystoring energy and increases the time to start. When the engine isrunning cons tan t l o a d d 0 inertiadoes not give orstore energy.During transients, it is seen that a hg he r inertia can control the speedchange to an extent within the limit. Hence the total inertia of thediesel system has to be designed suitable such that is less duringstarting and mor e at he transients. Therefore controlling over thefueling rate, inertiand the designed accelerationimit, thefrequency variation can be established within the limit.

I 97.5

The diesel generator shall be capable of running in parallel withstation auxiliary pow er system during the testing periods. Hence thediesel-generator contri buti on o the fault level shall be included inthe medium voltage switchgear design. Under the parallel opera tion,if a LOCA an d/o r loss of off-site power occurs, the diesel-generatorcan be quickly disconnected from the bus. The load shedding on theemergency bus including tripping of the necessary tie breakers shallprovide th e emergency bus readily available for connectin g back thediesel generator and sequentially load.

Shop tests shall be conducted according t o standard and guideson o ne or more pro totype s of the emergency diesel-generator sets toestablish the ability to start and accept load within 10 seconds and toload at least 60 percent of their full rating within 30 seconds afterthe star t signal is received.

The objective of testing d ieselgen erator is to establish a startingreliability of 0.99 with a co nfidence level8 of 0.95. The total numberof ests and available failures to obtain the above limit an beestablished from the following express iox8

1 c = N ! x (1-R)'x R N-y)Y! (N-Y)!

where C = Confidence levelR = ReliabilityY = Number of failuresN = Number of tests required

f 1.0 1 10 ;

PcacLc- 2ca3

0.75 -

1.25 -1.00.75-0.5 -0.25 r

-

D esign Req uire men ts of D iesel G en er at or A c ~ e s s o r i e s : ~ ~ ~ ~ ~

148 22 26TIMESECONDS

FIG. 7 GENERATORCURRENT,OUTPUT.VOLTAGE ANDFREOUENCYRESPONSERefer figure 7 for Voltage and frequency drop analysisEven though the diesel-generator voltage drop is limited by the

reactance, the duration of the voltage drop condition remains as ofthe load currentpattern . If the recovery is not established in theallowed duratio n, the low voltage bus loads and their contacto rs maydropoutdue o insufficient voltage. In order to recover ratedvoltage, a uitable fast acting voltage regulator providing enoughboost t o the system with wide band of uppe r and ower imits isrequired. Fro m the fipure, the increase in voltage and cur ren t around2 seconds from the loading time indicates the overshooting effect ofthe voltage regulator to bring stable voltage. Similarly the frequencyvariation is recovered by the fast response of the fueling system andthe dampingffect of the diesel-generator system inertia. If the 2.fueling rate acts fast enough to meet he angular deceleration, theengine can pick up the speed within 2 seconds to stabilize thefrequency.

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Auxiliary Systema) Engine shall be provided preferab lywith forced closed

cooling water system with shaft driven pump and suitableheat exdangers .

b) Lube oil system shall consist of piping, tank, heatexchangers and pumps (separately and shaft driven) tosupply sufficientub e oil with positive displacementpressure for bearings, piston ring, crankshaft and othe rengine parts.

c) Fuel oil system fora nuclear powerplant shall consistoftwo storage tanks, at least seven days capacity, ransferpumpswith necessary redun dant piping connecting to asingle day tank having at least fo ur hours capacity.

d) Each diesel engine shall have an independent air startingsystem consisting of two air receivers supplied by twoseparate electric mo tor driven compressors with necessaryredundant piping, valves, etc. Each air starting system shallbe capable of starting the engine for at least six cold starts.Necessary piping, safeguard features,ontrols,instrumentations and annunciationoints shall befurnished for the entire auxiliary system.

Instrument and Control:a) Each diesel engine shall be designed for manual and

automatic start with local contro l statio n a t the engine andremote control station at Main Control Room .

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Remote shutdown or hot shutdo wn system, used for safeshutdown ofeactor when Main Contr ol Room isinaccessible, shall ovemde ontrol from Main ControlRoom for the diesel unit.The diesel unit is started automa tically for he followingconditions:1. Loss of coolant accident condition2. Loss of off-site power.Initiating start signal for diesel generator shall trip allrunning loa ds on the respective emergency buses and star tsequential loading after he diesel-generator is connectedto the emergency b us and ready for loading.Each diesel unit shall be provided with load frequencycontrol system, speed regulation and fuel injection systemsuitably available for starting,ormalunningndtransients.Under governor co ntrol for overspeed and frequency, theinertia of he engine-generator and the connected loadshall be considered t o include ny flywheel effect ifnecessary.Suitable voltage regulato r with fast response characteristicto maintain voltage well above 90 percent in the rated timelimit and set limits for over- and underexcitation shall beprovided.The auxiliary system controls shall includeuitablethermostatic controlor lube and fuel oil systems,automatic level controloray tank and autom aticpressure control for air starting system.Suitable alarm and ndications shall be provided for hefollowing auxiliaries:1. Air receiver pressure f or Air Starting System2. Oil levels for day and storage tanks3. Temperature and pressure for jacketwater and lube

Oil4. Crank case pressure, fuel oil header pressure and

intake air manifold pressure and temperature andexhaust temperature and pressure.

REFERENCESU.S.A. AEC Reg ulato ry Guide RG 1.9IEEE 387-72ANS 56.1DEMA Standards and Practices fo r Low and M edium. SpeedStationary Diesel and Gas Engin esW.T. Pratt, Worked Examples in Electrical Engineering,Hutchinson Scientific and Technical Publication, Page 93-97(Induction Motor Torques).

j) The following Instruments and Relaying shall be provided:Instruments: Output voltmeterand ammeter, wattmeter,watt-hour meter, varmeter, field ammeter, synchroscopewith synchronizing and control switches, frequency meterand elapsed time meter. Necessary indicators for fuel oil,lube oil, jacket water and thermometers shall be providedon the engine and all othe r necessary areas.

Relays: Generator differential relay, reverse power,generatorovercurrent relay with voltage contro l, goundrelay, overvoltage relay, loss of excitation relay, engineoverspeed, low lube oil pressure, high crank case pressure,high jacketempe rature, high bearing tempe rature,generator bus fault.

-Conclusion:

A diesel-generator for a nuclear pow er station mu st be designedso as to provide reliable standb y pow er source for he engineeredsafety featu re load.

Aypical load study and the quation s or evaluating thediesel-generator ratings and eactances are developed taking intoconsiderations the AEC Regulatory guidelines for maintainingvoltage and frequencyimits of the generator during loadingtransients.

The study of t he engine sizing, inertia of the diesel system andfueling rate with reference to transientrequency variation areillustrated for engine manufactu rer to probe urther in the dieseldesign to arrive at an optimum sized diesel engine-generator systemwith the necessary standards and design capabilities.

Acknowledgement:I take the opportunity toexpress my sincere appreciation t o my

associates, Mr. K K Khanna, and Mr. M J Palossy, for their help inreviewing this paper and my thanks to EBASCO for providing thenecessary suppo rt in comp leting this assignment.

E.W. Kimbark Power System Stability Volume I Page 21-23Rotatio nal Loads and InertiaH.M. Hardy, T.W. Kearns, L S. Urley The Application ofMedium Speed Diesel Engine to Nuclear StandbyGeneratorService. Paper 73 DGP-19. ASME Publication April 1974k Morcos The Role of Probability on Nuclear Plant DesignConsulting Engineer, December, 1973

Photograph of Diesel Engine RV20-4 published under thecourtesy of DELAVAL - ENTERPRICE

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diesel generator ieee paper 01601575

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