This document contains information proprietary to AEP. It shall not be reproduced in whole or in part or released to any third party without expressed written consent of AEP.

Annual Peer Annual Peer -- Review Meeting Review Meeting

2020thth October 2005October 2005

Debosmita Das and Dave Nichols Debosmita Das and Dave Nichols

Power Conversion System (PCS)Power Conversion System (PCS)

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ACKNOWLEDGMENTSACKNOWLEDGMENTS

Funded in part by the Energy Storage Systems Program of the U.S.Department Of Energy (DOE/ESS) through Sandia National Laboratories (SNL).

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Topics of DiscussionTopics of Discussion

Introduction

Characteristics and Features

3-Level Inverter

Recommended Future Paths

Our Partners

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IntroductionIntroduction

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016-300

-200

-100

0

100

200

300

Time (s)

Va(

t), V

b(t),

Vc(

t)

LOC

AL U

SER

INTE

RFA

CE

RE

MO

TE U

SER

INTE

RFA

CE

DC

BUS

CA

PAC

ITOR

IND

UC

TOR

CO

NTAC

TOR

FUSE

125Vac/dcto 24Vdc

MPS Board

UCB

Gate Drive V-I-T sense

24Vdc Battery

HeatsinkBusbarVdc

kVdc

time

DC Voltage

IGBT

125Vdc Station Power

CONTROL BOX

BIDIRECTIONAL INVERTER

100kVA PCS TANK

DSP-BDSP-A

ALTERA

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PCS Unit PCS Unit –– Inverter CompositeInverter Composite

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PCS PCS -- SpecificationsSpecifications

• Low cost PCS ($50/kW) for the utility applications.

• Varying output voltage (480V/240V/208V) depending on the

input DC bus voltage.

• DC bus voltage range from 800-1600 V.

• AC output current of 120 Arms (100 kW).

• Efficiency around 98%.

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PCS PCS -- CharacteristicsCharacteristics

• Capable of operating in parallel.

• Inject and sink active and reactive power from the system.

• Reliable for all power system operations.

• Capable of both indoor and outdoor operations.

• Modular device facilitating bench-top assembly.

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PCS Unit PCS Unit –– ComponentsComponents

Eupec’s Dual Pack IGBT Module

IGBT Modules Mounted on Heat Sink

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PCS Unit PCS Unit –– ComponentsComponents

Control Box

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PCS Unit PCS Unit –– ComponentsComponents

Universal Control Board (UCB)

Main Power Supply (MPS)

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Transformer Tank

Transformer Tank + Oil

PCS Unit PCS Unit –– ComponentsComponents

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20 kW PCS20 kW PCS

• Sandia National Lab is currently reviewing the 20 kW prototype.

• The unit demonstrated bi-directional power flow using both active and reactive power.

• The unit also demonstrated functionality with a PV array.

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33--Level Level –– Electrical CircuitElectrical Circuit

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Why choose 3Why choose 3--Level Inverter?Level Inverter?

• Switching frequency for a 3-level inverter is reduced to about ¼th of that of a 2-level inverter.

• Switching loss is lower because of reduced switching frequency.

• Losses are more evenly distributed in double the number of IGBTs.

• Distribution of losses helps in * Eliminating the hot spots.* Enhancing heat dissipation from the IGBTs.* Reducing thermal gradient.

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33--Level Inverter: IGBT LossesLevel Inverter: IGBT Losses

IGBT Specifications:

Manufacturer: EupecModel No: FF400R17KE3_B2Collector Emitter Voltage: 1700 VDC Collector Current: 400 AMax. Junction Temp.: 125°C

100 kW PCS Specifications:

DC Bus Voltage: 800-1600 VOutput AC Voltage: 480 VRMS Current: 120 AFrequency: 60 HzSwitching Frequency: 500 HzPower Factor: 0.9

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33--Level Inverter: IGBT LossesLevel Inverter: IGBT Losses

166816201572152414761428139513411294Total Losses (12 IGBTs) [W]

744696648600552504471417371Total Switching Losses [W]

924924924924924924924924924Total Conduction Losses [W]

360336312288264240228198176Diode Switching Losses [W]

138138138138138138138138138Diode Conduction Losses [W]

384360336312288264243219194IGBT Switching Losses [W]

785785785785785785785785785IGBT Conduction Losses [W]

1600150014001300120011001000900800DC Bus Voltage (V)

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33--Level Inverter: Thermal TestLevel Inverter: Thermal Test

IGBTModules: Toshiba (MG150Q2YS51)Collector Emitter Voltage: 1200 VDC Collector Current: 200 A

IGBT Module

Heat Sink

Test Specifications:

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33--Level Inverter: Thermal TestLevel Inverter: Thermal Test

Mineral OilDielectric Strength = 45 kV Flash Point = 147 deg CFire Point = 165 deg C

Transformer Tank167KVA Single Phase34.5kV to 240VGrounded 3 WireFins on One Side

Test Specifications:

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167kVA Finned Tank Forced Air

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"Heatsink Top°C" "Oil Top°C" "Heatsink Bot°C" "Ambient°C"

"Tank Wall Right Top°C" "Tank Wall Right Bot°C" "Tank Wall Front Top°C" "Tank Wall Front Bot°C"

"Oil Bot°C" "IGBT Case 1°C" "IGBT Case 2°C" "IGBT Case 3°C" "Heatsink Mid Fin Top Mid°C" "Heatsink Mid Fin Top Edge°C" "Tank Fin Top Mid°C" "Tank Fin Bot Mid°C"

1 kW

2 kW

33--Level Inverter: Test ResultLevel Inverter: Test Result

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Inverter: Thermal Simulation Inverter: Thermal Simulation

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33--Level Inverter : ConclusionsLevel Inverter : Conclusions

• The 3-level PCS can be designed for DC bus voltage range of 800-

1600 V.

• Output AC voltage will be 480V and rms current 120 A. To

dissipate a total loss of 2 kW an 100 kVA transformer tank with fins

on three sides can be used.

• Estimated amount of oil required to cool such a system is less than

100 gallons.

From the simulations and thermal test carried out on the 100 kW,

3-level PCS design it was concluded that :

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33--Level Inverter : Cost EstimateLevel Inverter : Cost Estimate

Inverter Power Circuit Components Quantity Unit Price [$] Total Price [$] % Reduction Total Price [$]IGBT Module (each module has 2 IGBTs) 6 439 2634 20 2107.2Gate Drive Board 6 50 300 0 300Heat Sink 1 935 935 50 467.5DC Bus Capacitor 1 1000 1000 10 900V-I-T Sensors 1 690 690 0 690Laminated DC Bus 1 225 225 0 225Labor Cost for Assembly (1hr @ $50/hr) 1 50 50 0 50Total Cost for Inverter 1 3389 5834 - 4739.7Other PCS ComponentsInductor 1 1270 1270 0 1270Tank 1 500 500 0 500Oil (FR3 Ester Oil @ $10/gallon) gallons 10 700 0 700Contactor, 3-phase, 221A, 480Vac, 24Vac/dc coil 1 370 370 20 296Fuse 3 48 144 0 144Fuse Holder, 600Vac, 200A 1 155 155 0 155Inverter to Inductor Assembly material 1 50 50 0 50Control Board 1 1050 1,050 0 1050Main Power Supply 1 460 460 0 460DC Bus Initial Charge Device 1 500 500 0 500Labor Cost for Complete PCS Assembly (2h @ $50/h) 1 100 100 0 100Labor Cost for Complete PCS Unit Testing (2h @ $50/h) 1 100 100 0 100Total PCS Cost for 100kW 1 - 11,233 - 10064.7PCS Cost per kW ($/kW) 1 - 112.33 - 100.65

Cost for Single Inverter Cost for Mass ProductionComponents 3 Level Inverter (Output Voltage = 480V)

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Recommended Future PathsRecommended Future Paths

• Build a 100 kW Prototype Three-Level PCS

• Validate the Thermal Characteristics of the PCS

• Validate the Cost Estimates of the PCS

• If the thermal characteristics and cost meet the target,

then build three, 100 kW PCS operating in parallel and

complying to IEEE1547 standard.

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Our PartnersOur Partners

• American Competitiveness Institute (ACI)

• Heat Technology Inc. (HTI)

• Advanced Energy Conversion (AEC)

• Cooper Power System

• Ohio State University (OSU)

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Thank You!