ML17291B293

Adjustable-Speed Drive Retrofit for Ormond Beach Fd Fans

ML17291B293
Person / Time
Site:	Columbia
Issue date:	12/31/1995
From:	Mccluskey R, Oliver J, Weiss H BECHTEL CORP., GENERAL ELECTRIC CO., SOUTHERN CALIFORNIA EDISON CO.
To:
Shared Package
ML17291B292	List: GO2-96-075, Forwards Addl Supplemental Info Re Request for Amend to TSs on Reactor Recirculation Sys Adjustable Speed Drive Upgrade ML17291B293 ML17291B294
References
NUDOCS 9604150092
Download: ML17291B293 (30)

Text

cs 92 WM059-6 EC AD3USTABLE-SPEED DRZVE RETROFZT FOR ORMOND BEACH FD FANS Z. A. Oliver Bechcel Corporation R.

K. McCluskey Southern California Edison Co.,

H.

W.

Weiss General Electric Co.

Mo Z S amoco Electric Paver Research Znstitute hat ~

The boiler on Southern California Edison's 750 MW Oxmond Beach Unit 2 was extensively modified ta reduce minimum load f am 250 MW to 36 MW.

With the unit operating at minimum laad frequently at night, it became economically attractive to instaLL ad)ustable-speed drives (ASDs) on each of the 6250 hp Forced Draft Fan Motors.

The ASD technology that was used is a fourth generation current-souxce, GTO-PWM inverter that is used in a configuration foscered by a series of f've ASD field tests conducted for EPRZ by Bechtel in the period fram 1984 Co 1989.

This ASD concept has features that ensure the high degree af reliability that is needed in these high capacity utility paver plant applicatians.

These featuxes axe as follows:

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12 aulse invercer to minimize harmonics

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to the utility bus.

UPS fax'SD canal pover to eliminate outside influences on the aperatian of the ASD.

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Input t ansformer and gxound at the mocor side of the inverter to prevent high line-ta-naut al voltage an the motor.

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Selective harmonic elimination inverter control to preclude electrical resonance between output filter and mocor.

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Liquid cooling af thyristors to prevent temperature-related failures.

The Ormond Beach ASD system is the world's

largest, and most sophisticated of its kind.

These 7200hp ASDs have operated for 3 years with no backup

system, attesting to the reliability that can be achieved with this approach.

This aaner describes the application cancepc that has evolved om the EPRZ tests, the GTO-PWM ASD technology, field test results of 42 Qf 059-4 EC A paper zecoesseuded and approved by the

'EEE Electr'c Machinery Coassittee of the 1EEE L 1C'/

?over Engiteeritg Society for preseucacion ac the.=i

?ES 1992 "inter Ãeecia8, New York, New York. January 26-10.

1992.

Manuscripc subnitted July 12, 1991; made available for pristine January I,S, 1992.

paver savings, measured haxmanics at utility bus and at the motor, effect of THD reduction by using an input harmonic

filter, and operating experience ta date.

Fan inlet vanes have been

removed, and no ASD bypass was provided.

The technology for the ad)ustable-speed drives (ASDs) used for the Oxmand Beach Generating Station Unit 2 Forced Draft Fans resulted f om the experience gained in five FPRI-supported ASD fieLd tests that vera conducted by Bechtel for utilities between 1984 and 1988.

This faurth~eneratian induccion motor ASD technology i nov being reported to industry because of the reliability that is being demonstrated by this high-pover. high tec.'acology pover electronics speed control system.

The 7200. hp ASDs have been in operation for three years ac oxmond Beach The 6250 hpi 890 xpmy 13 '

kvg 1 15 service factor induction motors that drive the Unit 2 Farced Draft Fans are among the highesc horsepower motoxs in any of the Southern California Edison generating stations.

The armand Beach

plant, located in

Oxnard, California, has tva 750 MW supercritical pressure boilers.

Because the superc itical, ance-through boiler design does not lend itself to f equenc anmff cycling in an economic

manner, the unit" ara not typically shut dovn at night even though the output may not be needed during those hours.

The Unit 2

boiler has been extensively modified to allov operation at reduced minimum load vhich ls nav 36 MW, down from the 250 MW design value for minimum load.

Studies vera made in 1985 of the savings in unit auxiliaxy power that could be achieved if ASDs ware used to reduce fan speed at night vith the unit output reduced to as lav as 36 MW; These studies showed that the fan horsepower at.

minimum load with inlet vane contxol was 3000 hp per fan and that it could be reduced ta 250 hp per fan vith AsD cancrol.

The value af the energy saved vas estimated ac up to

$1.5 million annually depending an the annual load curve and the future case af fuel.

0 A

Zn the meantime.

EPRZ conducted

'eld tests ac the five following locac'ns with four dif erenc invexcer technologies:

9604150092 960404 PDR ADOCK 05000397 P

PDR 1984 D '992 IEEE

1. Sierra Pacific Power Co.,

Ft.

Churchill Plant.

1"2000 hp Boiler Feed Pump ASD vith 12-pulse current source inver er, air cooled.

1985 Feed Pump ASD with 12-pulse current source inverter, air cooled.

2. Gulf States Utilities, WiLlow Glen Plant.

1-2250 hp Boiler Feed Pump ASD with 6-pulse modified load-commutated inverter (SCR type),

water cooled.

1988 3.

Zowa Public Service Ca., Neal PLant.

2-6300 hp Boiler Feed Pumg

ASDs, modified load-commutated inverter (GTO type), air cooled.

1987

4. oklahoma Gas Electric co.,

Seminole Plant.

2-5000 hp FD Fan

ASDs, current-source GTO-PWM inverter, air cooled.

1988

5. Sierra Pacific Power Tracy Plant 1-2000 hp Boiler Feed Pump

ASD, c~ent source GTO-PWM inverter, air caoled.

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Twelve-pulse input to minimize harmonics to the power system.

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Input transiormer and system ground From the experience gained in these field

tests, EPRZ fostered a concept for an advanced high-horsepower utility type induction motor ASD.

General features that were identified for this ASD are as follows:

on the motor-side of the'inverter to control Line-to-ground voltage at the motor.

Water cooling of thyristars for more effective heat removal.

UPS system for ASD controls to eliminate outside influences that could affect operation of ASD fizing circllits Means to prevent resonance between the output filter capacitor and the motor that can happen near half frequency and belaw.

This electrical resonance has caused high lateral and torsional vibration in some ASD installations.

The EPRZ concept is depicted in Figure 1 and was strictly applied in the Ornond Beach installation.

The ASDs are a

fourth generation in 'echnology development as compared to the Ft. Churchill ASD.

Specific deveLopment features in the new ASDs are as follows:

Watemooled rectifier thyristors, water-cooled inverter GTO thyristors and water-cooled snubber resistors.

Symmetrical GTO thyristors, eliminating the need for blacking INPUT FORMER USE OF INPUT TRANSFORMER FOR I2~ ORI~

OPERATloN SUILTANTOLERANCE FOR 8US VOLTAGE UPS SWINGS SPIKES ANO INTERRUPTlaNS OC UNK ANO OC UNK INOUCTOR WATER COOLEQ THYRISTORS FOR SIMPUREO COOUNG.

IN+II THYRISTORS FOR REDUNDANCY GTO THYRSTQR CONTROL TO PREVENT RESONANCE 8EnVEEN OUTPUT FK.TER ANO MOTOR OUTPUT FILTER GROUNOINQ OF SYSTEM: TO STA8IUZE MOTOR VOLTAGEANO OC UNKVOI.TACE MOTOR MOTOR rlgure 1

PREFERRED CONFIGuRATION FOR LARGE POWER PLANT ASD TYPICAL 4160 VOLT SYSTEM 2

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Vorrnol inverter outout c'rent The control is implemented by one 80286 microprocessor vhich provides the regulator, protective and diagnostic functions and a

self-checking diagnostic pragram at power up.

The regulator functions include a outer speed loop vith inner control loops for motor torque, current and flux.

In addition, a

SHE (Selec"ive Harmonic Elimination)

Cunctian is implemented by PHM (pulse width modulation of the inverter output current to prevent high current and torque at the resonant frequency of the LC load circuit.

Figure 3

shows an example of the FWM pattern for SHE.

II LII8" gl L

PWM inverter output current for eiiminotion of 5th ond itn hormonic current

=:-"=.= 3 Seleciive,'-,'chic,". c =iimino;i".n thyristors in

series, each having a

peak repetitive forvard voltage rating of 4500 volts and peak reverse valtage rating of 4000 volts.

The peak maximum voltage applied by the c'rcuit is 5900 volts, again permitting t

Cull capability with three GTO's operational nd one shorted.

The GTO devices operate at F

05'C maximum, again belov the design junction emperature of 125'C.

Each thyrsitor device has an R-C snubber network, voltage equalizer resistor and a gate driver which is optically coupled to the low voltage cont ol system.

The liquid cooling system is a

self-ventilating closed loop system using a

deianized water/glycol mixture with forced circulation and liquid to air heat exchanger for 50'C ambient air.

Redundant full capacity pumps and heat exchanger fans vith automatic change-over are supplied.

The cooling system removes the losses of the thyristor devices and snubber resistars.

After start-up of the ASD equipment in June, 1988, tests were conducted to verify the Can paver over the speed and load range with ASD cant ol.

Test" had been made before the installation of the ASDs to obtain Can paver measurements vith vane cont ol.

The results of the

tests, shown in Figure 4, verified calculations made before the start of the project.

Motor input frequency and motor speed for different MH loading are shown in Table 1.

The manufacturer of the PD Cans recommended fan rotor replacement with a new rotor design with less propensity to develop fatigue cracks.

Calculations and tests vere performed vith old and new rotors (Figure 4).

Figure 4 OAMONO 8EACH - FO FANS AS0E MOTOR SHAFT HORSEPOWER vs. GROSS MW QLO ROTOR VANE CQITIICLTEST>>

4XN QLO AOTQIIVAIIE COIITIIQLCILC QIO tOTQII CALO@SO TEETATO>>

~ CILC IIEW IIOTQII e

TEST IIETIAOTOII a, CLLC OLO IIQTQII C2 cILQ QLQ IIQTQA 0

TETT IXDKYCQII 200 xe 400 500 IIIWOUTPUT

FlgLIre 5 THD-V INPUT RPM CALC Na FILTER pERcENT THD CALC FILTER TEST NO FILTER TEST FILTER CILCULLTTOTHO WITHOUTFILTTA 100 75 50 25 4.95 5.3 4.3 3.14 1.3 2.25 1.9 1.35 97.5 93.7 57 40 35 3.57 3.27 3.1 2.2 1.9 0.5 0.7 0.5

'I.O THOV 3

Tee'T WIO FILTEA THO TIARAT WITH F T4A F4A ~C.

CALCULATKOTHO WITH F%.TEA TfTTXO TWO WITH FILTTA I

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I 50, TS 100 IL AFM TABLE 1

ASD CONTROL OF FD AIR AT ORMOND BEACH HE 750

~667 hr 58 ~ 5 56 ~ 25 40'8 24.02 21 76 BBH 833 802 580 342 310 930,000 900,000 660,000 400,000 350F000 Original calculations had shown a

maximum voltage total harmonic distortion of 5.24 at the 13.2 kV bus because of tho rectifior harmonics.

Because of concern for the possible effect of these harmonics on other plant components, an input harmonic filter vas installed on the bus.

Tests showed harmonics levels as in Figure 5 with and without tho filter. Without the filter, input THD at full load was 3.2 percent.

With the filters in

service, maximum input voltage THD vas 1.3 percent.

Harmonics have not been a problem, vith or without the filter, and the filter itself has not caused any problems.

ASD efficiency at full load vas measured at 97.54 as consistent vith the manufacturer's expectations.

The ASDs vent into service in June, 1988 with relatively fev problems.

Tho ASDs carry an availability guarantee and a multiyear parts and labor warranty.

Since installing the

ASDs, the plant operators have chosen to operate these fans without inlet vanes.

Thus, the fans have operated vithout a

backup control system in casa of ASD failuxe.

Initial problems vere as follavs7 but it should be stressed that neither of these ASDs has ever caused a critical shutdown of a fan or a shutdown of the generating unit since its first day of in-service opex'ation:

1.

The output voltage,

current, and volts per hertz prafiles required field adjustment to allav rated output voltage of the ASDs.

2.

The transformer taps on one input transformer were set.

on the lowest tap and required ad)ustmont.

3.

An intermittent internal electrical noise source caused an extra zero crossing in the control voltage to tho ASD causing erroneous operation.

4.

The input transformers had a

damaged sudden pressure relay and developed oil leaks at the oil level gauge.

5.

Leaks developed in the external copper water piping from poor brazing.

6.

The cooling fans an tho water-to-air heat exchangers are noisier than expected.

7.

A delayed auxiliary bus transfer because the bus voltage vas maintained by the input harmonic filter capacitors.

8.

Input capacitor liquid leaks from shipping damage.

9.

A few isolated electronic component failures from unknown causes during start-up.

10.

Nuisance ground tripping during start-up from an overly sensitive ground detector and feeder cable capacitance.

11.

Cooling vater conductivity alarms during initial system cleanup.

12.

ASD cabinet viring errors.

Solutions to all these problems except the noisy heat exchanger fans have been implemented.

Operation of the forced draft fans vith ASD control xecoived immediate acceptance by the control room operators.

Problems af inlet vanes freezing in one position have been eliminated.

The fine control offered by the ASDs has been far superior to the inlet vane control which had a long tradition of problems at this sita:

The heat rate improvement resulting from the FD fans ASDs is shown in Table 2.

TABLE 2

CULATED HEAT RATE IMPROVEMENT FROM ASDS uzamum 60 19,771 272 10,111 348 9,834 425 9,656 502 9,506 578 9,522 655 9,538 732 9,645 1038 138 105 91 79 39 14 10 0

1 5

7 11 13 58.5 291 410 640 760 11, 549 658 263 103 68 306 13 4

1 1

output wave shape of the ASD contains no tage spikes.

There was no evidence of ditional motor heating or vibration at. any operating speed..

Figure 6 VOLTAGEAND CURRENT WAVESHAPES 6695 HP, 58M Hz s v~arr tso There was no observable effect of the ASD causing degradation of motor performance.

Motor line-to-line voltage and line current wave shapes with the Unit at 750 MW are shown in Figure 6.

Operating at about 6695 horsepower and 58.5 Hz, voltage and current harmonics were as follows:

TABLE 3 HARMONICS TO THE MOTOR AT 750 MW LBlZEolliRR E'XQRQLXl, ~vv~

~~z9~

~CO ~g~~

The experience with these two 7200 hp induction motor ASDs demonstrates that highly reliable ASDs for power plants are available.

By using the application engineering approach outlined in this paper and by taking advantage of these new developments in high power ASD

design, utilities and their industrial customers can now gain the benefits of this advanced technology without the concerns for reliability of power electronics.

"Application of Adjustable-Speed Drives for Large Power Plant Motors", J. A. Oliver and R.

A.

Martinson.

Pacific Coast Electrical Association, Engineering and Operating Conference, March 17, 1983.

"Conversion of Boiler Feed Pump to Adjustable Operation",

Wilbur Montgomery, James A.

Oliver, Ralph J.

Ferraro.

Pacific Coast Electric Association, Engineering and Operating Conference, March 20, 1985.

"Retrofitting for Variable Load and Sliding Throttle Operation:

Adjustable Speed Drives<<,

James A.

Oliver, Ralph J.

Ferraro, Wilbur Montgomery, Eugene K. Kempers.

American Power Conference, April 24, 1984.

"Converting Motors in Power Plants To Adjustable Speed Operation with Power Electronics", J. A. Oliver and R. J. Ferraro.

CIGRE International Conference on Large High Voltage Electric Systems, September 1,'1986.

"Power Measurement and Harmonic Analysis of Large Adjustable Speed, Drives", J.

A. Oliver and B.

Ben Banerjee.

ZEEE Summer Power

Meeting, San Francisco, July 15, 1987.

"Symmetrical GTO Current Source Inverter for Wide Speed Range Control of 5300 to 4160 volt, 350 to 7000 hp Induction Motors."

Paul

Espelage, James M.

Nowak, Loren H.

Walker.

IEEE-ZAS Annual Conference, October 2-7, 1988, Pittsburgh, PA.

"Proven Criteria Imperative to the Application of ASDs to Large Power Plant Motor Systems",

James A. Oliver and Marek J.

Samotyj.

IEEE Summer Power Meeting Minneapolis, July 15-19, 1990.

"Lessons Learned From Field Tests of Large Znduction Motor Adjustable Speed Drives, 1984-1989", J

'A. Oliver and M. J.

Samotyj CZGRE Conference, August 26-30, 1990, Paris.

Mr. James

• Oliver - S.M. received the B.S.E.E (1950) from the University of Maine and the M.E.E.

(1960) from the Polytechnic Institute of Brooklyn.

He is the Product Line Manager for Adjustable Speed Drives for Bechtel Corporation in Noiwalk, California.

and he managed the EPRI ASD power plant retrofit project starting in 1982.

k.l Herbert W. Weiss

- Received the BSEE degree from Lehigh University, Bethlehem.

Pennsylvania kt 1952.

He joined General Electric Company in 1952 and has worked in various capacities related to the installation and design of power electronic equipments and systems for adjustable speed motor drives.

His prior experience indudes Vlce4>resident of Engineering for the National Electric Coil Division of the McGraw Etflson (1971-1978) and Rotating Machineiy Specialist for American Electric Power Service Corporat/on (1950-1971).

Mr. Oliver is VfceChalrman of the IEEE Elecuic Machinery Committee, A U.S. Expen on CIGRE Comminee 11 - Rotating Machines and a member of the ANSI C50 Rotating Machinery Committee.

He has authored a number of papers related to rotating electrical machinery and adjustable speed drives.

He is presently Manager, Advanced System Engineering for AC and Special Process Drives at the GE Drive Systems Plant in Salem, Virginia Mr. Weiss has authored six technical papers on adjustable speed ac drives and holds seven patems.

He is a Senior Member of IEEE Marek Jan Samotyj is a Senior Project Manager in the Power Elecuonics and Controls Program, of the Customer Systems Division. at the Eleculc Power Research Institute (EPRI) in Palo Alto,CaNomia. Durin 1984, Mr. Samotyj was a Consultant for Power Electronic Systems at the institute.

He joined the Institute as an employee in 1985.

Before coming to EpRI, Mr. Samotyj was a Research Assistant for the Energy Modeling Forum at Stanford University (1982-1985).

From 1980 to 1981, Mr. Samotyj was a Consulting Member of the Scientific Board of the Future Research Center at Technical University in Wrocfaw, Poland, and a Consultant for R5D planning strategy with the Commission on the National Economic Reform in Warsaw, poland.

From 1971 to 1975, he was a Consuming Staff Engineer and project Manager for the polish Ministryof Mining and Energy.

Mr. Samotyj received his B.S.

(1969) and M.S. (1971) degrees in Electrical Engineering from SiIeshn Polytechnfcal University of Glbiice,

Poland, He received an M.S. In Engineering<conomics Systems from Stanford University In 1985.

From 1981 to 1982. Mr. Samotyj was a Fulbrlght Senior Scholar, and the Fellow of the Professional Journalism Program at Stanford University.

Mr.

R.

K.

(Bob)

McCluskey

- is cunently a Senior Research Engineer and Project Manger in Southern California Edison's Research Division and responsible for Electronic Controls and Diagnostics, Power Quality Analysis, and Technology Transfer.

Hfs professional background Includes a Bachelor of Science degree in Eiectrical Engkteering from lowe State University of Science and Technology and nineteen years ln the electric uuTity indusuy.

He has work experience in the planning, sMng, design, construction and stanu p of major steam elecufc generating plants, energy service facilities, and pollution control apparatus, as well as research and development associated with emerging advanced technologies including fuel cells, bulk energy

storage, electrfc transponatlon, groundJault detection, energy metering, adjustable speed drives, variable speed generation, expert monitoring and diagnostics, and most recently utility regulatory po6cy matters.

Mr. McCluskey has served as a utility advisor to the Electric Power Research Institute, and Is a member in good sta'nding ofTau Beta Pl, Eta Kappa Nu. and the Airand Waste Management Assoc'ation.

He Is a member of the institute of Efectricaf and Electronics Engineers and a member ofCIGRF International Conference on Large High Voltage Electric Systems.

Discussion of:

ADJUSTABLE SPEED DRIVE RETROFIT FOR ORMOND BEACH FD FANS By:

J.

A. Oliver, et al.

N. E. Nilsson (Ohio Edison Company, Akron, Ohio)

The authors are to be congratulated for their develop-ment of another excellent paper in a series of papers on adjustable speed drives (ASDs).

Perhaps the most important information in this paper is the tabulation of possible problem areas.

This reviewer recalls the problems experienced with the isolating transformers installed as part of the ASD system at the Ohio Edison Company R.

E. Burger Plant due to harmonic heating which had not been factored into the original design.

Would the authors elaborate on what was done to address the problems identified.

Were the cooling fans on the water-to-air heat exchangers noisier than expected because they were defective, or was it due to a

differently designed fan than specified2 Vere defective fans replaced2 Vas the fan design modified2 What specifically were What impact did the changed the system2 What kinds discovered2 How long did it the electronic failures2 bus transfer time have on of wiring errors were take to correct them2 The features applied as a result of field experi-ence appear to be very beneficial.

How has the control system with a UPS performed in relation to controllers powered from standard plant electrical systems based on the authors'xperience?

What was the means used to prevent resonance between the output filter capacitor and the motor?

How much reduction in lateral vibration has been realized2

Discussion Question for:

ADJUSTABLE-SPEED DRIUE RETROFIT FOR ORMOND BEACH FD FANS This is an interesting paper on a timely subject. I was especially pleased to see the comments from the operations people concerning the improvement in unit operation.

We are evaluating a project to retrofit FD fans at one of our larger power plants.

We are well aware of the efficiency

gains, the reduced maintenance, the operation benefits, and the long term improvement in equipment life. Cost to benefit ratios are attractive which means the economic consideration is favorable.

However, a question comes t:o mind concerning the investment.

Was there dialogue with the pUC on this project before or after its completion?

How did Southern California Edison Co. address this expense with regards to the rate base.

I'elieve it would be interesting to the readers to hear more information on this aspect of the project; perhaps Mr. McCluskey could comment.

J.R.

Michalec American Electric Power

Columbus, Ohio

DISCUSSION 91JPGC 559-5 PWRS ADJUSTABLE-SPEED DRTVE RETROFIT ORMOND BEACH FD PANS BY J.A. Oliver H.W. Weiss R.K McCluskey M.J. Samotyj DISCUSSION BY

¹weH S. Porter Washington Public Power Supply System P.O. Box 968, MS 580 Richland, WA 99352

Discussion KS. Porter (Washington Public Power Supply System):

The success of the Ormond Beach Project has prompted us at the Supply System to accelerate the application ofadjustable speed drives (ASDs) in two areas, megawatt savings and improved plant performance.

Our first application will apply this technology to drive the reactor recirculation coolant,(RRC) pumps.

The design of the RRC system relies on two 8900 HP induction motor driven centrifugal pumps to force coolant through the reactor core. Varying the core coolant Qow rate is a primary means of controlling reactor power level.

This is accomplished by using a 15Hz motor-generator set to drive the motors at a slow speed and then switching to 60Hz for fast speed.

Flow adjustment is accomplished by using hydraulically operated flow control valves, a method analogous to driving ones automobile with the engine at constant RPM and controlling speed using the brakes! Not only is this a waste of energy, but the resulting turbulence causes excessive vibration in the piping systems.

The ASD willcontrol flow and reactor power with motor speed, thus conserving energy, eliminating excessive vibration, and reducing mechanical stresses during startups, shutdowns and control rod sequence exchanges.

Our equipment will be similar to that reported in this paper.

The motors are rated for 6900 volts so input and output transformers willbe used for the 4160 volt ASDs. Asignificant development will be a two-train system, as shown in Figure 1, for each ASD with the capability to operate with either one.

For two-train operation, the ASD'will be 12-.pulse input, 12-pulse output.

For single train operation, the ASD will be 6-pulse input, 6-pulse output.

The capacity of a sinj~e train is 7200 HP or 80 percent of the RRC pump rating.

Tn addition to the two-train capability, the ASDs have one extra SCR thyristor in each inverter leg and one extra GTO thyristor in each inverter leg (N+1). Based on the high degree ofreliability achieved at Ormond Beach and the redundancy ofthe two-train system, along with the (N+1) feature, the existing valve control systems and 15 Hz motor-generator sets will be removed at

%NP-2 when the RRC pump ASDs are installed.

It is noted that the paper does not discuss another positive aspect of ASD application, the soft starting of motors.

The drives essentially eliminate the high inrush currents typical of motor starting, thus reducing thermal and mechanical stresses.

Figure 1

WNP-2 RRC ASD

CLOSURE FOR "ADJUSTABLE-SPEED DRIVE RETROFIT FOR ORMOND BEACH FD FANS" The authors vish to thank the discussers for their contributions vhich add considerably to the breath of the paper.

In response to Mr. Nilsson, the 2 hp cooling fans on the air-to-vater heat exchangers are still noisier than the 6000 hp FD fans when the FD fans are operated at reduced speed.

The problem exists because the ASD specification did not address a noise limit on the cooling fans.

Without contract language, the ASD manufacturer does not recognize this as a problem.

The isolated electronic failures mentioned in the paper was one GTO and one circuit board failure during the start-up period.

Replacements vere guxckly made.

Wiring errors in the ASD cabinet vere related to relays added as part of the syst: em interface.

Once the effect of the harmonic filter in maintaining bus voltage during bus transfer vas seen, the transfer scheme vas modified to trip the filter before initiating transfer.

Four major reliability enhancements used vith the Ormond Beach ASD installation are as follows:

~

Grounding of the motor side of the ASD to let line-to ground voltage excursions occur within the input transformer 004

Supplying ASD control gower from a UPS Water cooling of the thyristors N +

1 thyristors and GTO's in each circuit As a result of these features there have been no ASD related trips of the FD fans or of the Unit.

Several of the 5 ASD EPRI sponsored field test installations have continued to experience thyristor failures that are either related to high operating temperature or control voltage problems.

It appears from experience that the Ormond Beach reliability performance.

features significantly improve Resonance between the output filter and the motor leakage reactance is totally eliminated by the selective harmonic elimination feature of the ASD.

In the PHM algorithm, harmonics are eliminated when they can produce a

frequency of 150 hz so that there

's no resonance.

The harmonics that are eliminated are as follows:

fundamental fre enc hz 11.5

13. 6

21. 4 30.0 harmonic order 13 frequency eliminated 150hz 150hz 150hz 150hz There has been no motor vibration, lateral or otherwise, as a

result of operating with these ASDs.

004

0

Mr. Porter has pointed out that the approach used to engineer reliability into the ASD system at Ormond Beach has led directly to the decision by Washington Public Power System to install ASDs on their 8900 hp Reactor Recirculating Pumps (RRC) at WNP-2.

They have decided to remove the hydraulically operated RRC system control valve and replace it with a spool piece.

According to Reference 1, with the dual train system proposed for WNP-2 there would be significant increase in reliability.

From Reference 1,

the mean time before failure (MTBF) for Ormond Beach would be 48,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> and for WNP-2, 137,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />.

ln response to Mr. Hichalec's inquiry, discussions were held with a representative of the Public Utilities Commission after the ASDs went into service (at the request of the PUC).

Because of the annual fuel cost savings, which were calculated to be over $500,000 per year, and which were verified by tests, before and after the ASD installation, the cost of the ASD installation was allowed in the rate base.

P.

K. Steiner and A. B. Giesecke "Increased Availability of Large AC Adjustable-'Speed Drive Systems" American Power Conference Chicago, April 1991.

004

Mr. McCluskey is presently a Senior Research Engineer and Project Manager in Southern California Edison's Research Division Quality Analysis.

His professional background includes a

Bachelor of Science degree in Electrical Engineering

&ozn iowa State University of Science and Technology and twenty years in the electric utilityindustry.

He has work expexience in the planning, siting, design, construction and startup ofmajor steam electric generating

plants, energy service facilities, and pollution control apparatus, as well as research and development associated with emerging advanced technologies including fuel ceOs, bulk energy storage, electric transportation, ground-fault detection, energy metering, adjustable speed drives, variable speed generation, expert monitoxing and diagnostics, and most recently utilityregulatory policy matters.

Mr. McCluskey has served as a utilityadvisor to the Electric Power Research institute, and is a member in good standing of Tau Beta pi, Eta Kappa Nu, and the Air and Waste Management Association.

013

LJ

DISCUSSION OF PRO3ECTS Ormond Beach FD Fan ASD's Z6 KY 4 KV I

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5th 1th ltth 13th 7200 hp 7200 hp Figure 6 ORMOND BEACH FD FAN ASD's Measured harmonic data had been obtained prior to testing the two 7200 hp adjustable speed drives (ASD's) at Southern California Edison's Ormond Beach Plant in 1989.

The Qrst use of V-Harm was to calculate the harmonics produced by the ASD rectifier and compare it to test data.

Because of the advanced engineering content of the program and the brief instructions supplied by Cooper, three to four weeks were required to develop proficiency in using the program.

The Ormond Beach calculations were carried out with close approximation to the Geld test data.

The program's output data was simplified by using an auxiliary program.

Figure 6 shows the simplified single line diagram used in modeling the Ormond Beach Plant, Unit 2.

Figure 7 provides some additional detaQ for the two 7200 hp ASD's that were installed on the Unit 2 Forced Draft Fans.

As can be seen in Figure 7, three-winding 12

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1.1%4'igure 8 ASD CURRENTS AND VOLTAGES MEASURED AT ORMOND BEACH 14

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