©2008 www.sandc.com©2008 www.sandc.com

Application of InverterApplication of Inverter--Based Systems for Peak Based Systems for Peak Shaving and Reactive Power ManagementShaving and Reactive Power Management

Ken Ken MatternMattern, S&C Electric, S&C ElectricAbraham Ellis, Public Service of New MexicoAbraham Ellis, Public Service of New Mexico

Ali Ali NouraiNourai, AEP , AEP Steven E. Williams, S&C ElectricSteven E. Williams, S&C ElectricCharles Edwards, S&C ElectricCharles Edwards, S&C Electric

Dave Porter, S&C ElectricDave Porter, S&C Electric

Case studies Case studies –– InverterInverter--based Applicationsbased Applications•• Distributed Energy Storage SystemDistributed Energy Storage System

–– AEP systemAEP system–– Peak shavingPeak shaving–– NaSNaS batteriesbatteries

•• Reactive Power Compensation for Wind Power PlantReactive Power Compensation for Wind Power Plant–– 90 MW WPP on PNM system90 MW WPP on PNM system–– Zero reactive power exchange at POIZero reactive power exchange at POI

DESSDESS

•• DDistributed istributed EEnergy nergy SStorage torage SSystem ystem •• AEP Charleston Energy Storage ProjectAEP Charleston Energy Storage Project•• SodiumSodium--Sulfur (Sulfur (NaSNaS) batteries ) batteries –– NGKNGK

–– 1.0 MW with 1.2 MW short time rating, 7.2 1.0 MW with 1.2 MW short time rating, 7.2 MWhMWh–– 300300ººC to 360C to 360ººC operating temperatureC operating temperature–– Vacuum enclosedVacuum enclosed–– 20 x 50 kW modules20 x 50 kW modules–– 2500 to 4000 cycles, 15 year life2500 to 4000 cycles, 15 year life

•• 1212--kV feeder, peak shave an overloaded substation kV feeder, peak shave an overloaded substation transformer to defer upgrade to larger substationtransformer to defer upgrade to larger substation

Simplified DESS Power CircuitSimplified DESS Power Circuit

Load and DESS Power ProfileLoad and DESS Power Profile

+ 1.2 MW Charge

- 1.0 MW Discharge

+ 1.2 MW Charge

- 1.0 MW Discharge

Example Profile from First Day of OperationExample Profile from First Day of Operation

Predefined ProfilesPredefined Profiles

DESS InstallationDESS Installation

Current DESS ActivityCurrent DESS Activity•• Direct control of real and reactive power with local Direct control of real and reactive power with local

override based upon frequency and voltageoverride based upon frequency and voltage•• Distribution feeder support in coordination with S&C Distribution feeder support in coordination with S&C

IntelliTeamIntelliTeam systemsystem•• Operation with wind generatorsOperation with wind generators•• 1 MW in service1 MW in service•• 5 MW in process5 MW in process•• Expect a total of 9 MW in 2008Expect a total of 9 MW in 2008•• 1 1 –– 5 MW unit sizes with larger systems in discussion5 MW unit sizes with larger systems in discussion

Dynamic CompensatorDynamic Compensator

•• DDistributed istributed STATSTATicic COMCOMpensatorpensator (DSTATCOM)(DSTATCOM)•• 90 MW 90 MW WindfarmWindfarm on PNM system, Type 1 wind on PNM system, Type 1 wind

generatorsgenerators•• Voltage stability limited 345 kV transmission with Voltage stability limited 345 kV transmission with

200 MW HVDC and 204 MW WPP200 MW HVDC and 204 MW WPP•• No reactive power exchange at the POINo reactive power exchange at the POI•• ±± 12 12 MVArMVAr DSTATCOM, 4 x 34.5DSTATCOM, 4 x 34.5--kV Capacitor banks kV Capacitor banks

total 91 total 91 MVArMVAr•• Short time rating of 3.3 per unitShort time rating of 3.3 per unit

OneOne--Line Diagram of Compensation SystemLine Diagram of Compensation System

WPP MW, Inverter WPP MW, Inverter VArsVArs and Net and Net VArsVArs at POIat POI

-20

0

20

40

60

80

100

0 1 2 3 4 5 6 7 8 9 10 11

MW

, MV

AR

Hours

Inverter MVArWPP Net MVAr

WPP MW

Wind Power Plant Collector VoltageWind Power Plant Collector Voltage

0.95

0.96

0.97

0.98

0.99

1

1.01

1.02

1.03

1.04

1.05

0 1 2 3 4 5 6 7 8 9 10 11

Volta

ge, p

u

Hours

Vdr puVdr pu

Capacitor StatesCapacitor States

1

2

3

4

0 1 2 3 4 5 6 7 8 9 10 11

Cap

Ban

k S

tate

Hours

13 MVAR #4

26 MVAR #3

26 MVAR #2

26 MVAR #1

Dynamic Compensator InstallationDynamic Compensator Installation

Questions?