Grid Interface for Wind- Advanced Functions

ARPA-eGreen Electricity Network Integration Workshop

Dec 13, 2010

Ravi RajuGE Global Research

2

Technology• Reliability & Efficiency

Cost• 85% in last 25 years

Policy• EU: 20% renewables by 2020• US: PTC, … 33 states have RPSs

Renewables Growth – Where we are

Global Wind & PV annual installations Last decade …. key drivers

3

UK:20% Renewables by 2020

Germany:20% Renewables by 2015

Spain:20 GW Wind by 2011

EU:20% Renewables by 2020

China:30 GW Wind by 2020

India:12 GW Wind by 2012

Japan:3 GW Wind by 2010

Targets in 73 countries

DOE Study: 20% wind energy by 2030

US: 33 states have Renewable Portfolio Standards California: 33% Renewables by 2020..

Renewables – Where we want to go

4

Wind Integration Challenges Are Broad

Longer time scale problems –grid dispatchability

Shorter time scale -dynamics and transients(power electronics )

Unit Commitmentand

Day-Ahead Scheduling

Load Following(5 Minute Dispatch)

Frequency and Tie-Line Regulation

(AGC)

Day-ahead and Multi-Day

Forecasting

Fast

er (s

econ

ds)

Ti

me

Fram

e

Slo

wer

(Yea

rs)

Planning and Operation Process

TechnologyIssues

Hour-Ahead Forecasting

and Plant Active Power Maneuvering and

Management

Resource andCapacity Planning

(Reliability)

Unit Dispatch

0

100

200

300

400

500

600

700

0 2000 4000 6000 8000

Hour

MW

Real-Time and Autonomous Protection and Control Functions

(AGC, LVRT, PSS, Governor, V-Reg, etc.)

Capacity Valuation(UCAP, ICAP)

andLong-Term Load

Growth Forecasting

2001 Average Load vs Average Wind

0

5,000

10,000

15,000

20,000

25,000

30,000

1 6 11 16 21

Hour

NYI

SO L

oad

(MW

)

0

200

400

600

800

1,000

1,200

1,400

1,600

Win

d O

utpu

t (M

W)

July load August load September load

July wind August wind September wind

0

500

1000

1500

2000

2500

3000

1 61 121

Minute s

MW

September Morning A ugust Morning May Evening October Evening April Af ternoon

1 Year

1 Day

3 Hours

10 Minutes

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Challenges for Wind Integration

• Interconnection• Performance through voltage sags• Variable power – freq reg, ramp rates,

curtailment…

• Intermittency• Must be overcome with dispatchable

energy assets• Unit commitment based on day-ahead

forecasts• Regulation costs

• Lack of Inertia• Penetration of wind displaces

conventional assets with inertia

• Non-collocation with load• Long-distance T&D makes economics

more challenging

58.00

58.50

59.00

59.50

60.00

58.0 a fbul 90 Load 220.0 1 1 60.058.0 b fbul 90 Load 220.0 1 1 60.058.0 c fbul 90 Load 220.0 1 1 60.058.0 d fbul 90 Load 220.0 1 1 60.0

Time( sec )0.0 30.0

U n d e r - f r e q u e n c y l o a d s h e d d in g t h r e s h o ld

Voltage

Power

Voltage Ride-Through

Inertia - Effect on Frequency

2.70

2.90

3.10

3.30

3.50

3.70

3.90

4.10

0 50 100 150 200 250

seconds

MW

59.94

59.96

59.98

60.00

60.02

60.04

60.06

Hz

Grid weakness - Effect on Frequency

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LVRT

Application CharacteristicsSingle WTGs Large Farms Multiple Farms

Low Penetration High Penetration

Perf

orm

ance

Req

uire

men

ts

Basi

c

Ad

vanc

ed

O/U VoltageOvercurrent

O/U Frequency

Anti-islanding

PF control

Voltage control(old DVAR)

Zero-PowerVoltage Control

None

Protection Volt/VAR Control

Active Power Control

None

LVRT – no trip(e.g. Taiban, E-ON)

Zero VRT – no trip(e.g. Quebec,

Western Australia)

LVRT with controlled current injection

Curtailment

Frequency Regulation

InertiaActive Anti-islanding,Torsional,

others

Coordinated Voltage Control

(WindVAR, WFMS)

State-of-the-Art for Wind Integration

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Focus Areas:Security• Grid fault tolerance and recovery

Operability• Voltage regulation• Active power controls

Planning• Assessment and planning tools

Grid-Friendly Features

Low Voltage Ride-Thru

Voltage

Power

Pavail

Pout

Grid

Fea

ture

s

Volt/VAR control

High Penetration

Blackstart / Island Active Power

ControlsLow Voltage

Ride Thru

InertialResponse

Zero VoltageRide Thru

WindFREEVoltageControl

2003 2004 2005 2006

0

20

40

60

80

100

47 48 49 50 51 52

Active Power

Ramp Rate

Freq. Droop

Pow

erPo

wer

Frequency

Time

GE Wind – Grid Integration Features

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Voltage Regulation

Measurements: 162MW wind plant• Regulates Grid Voltage at Point of Interconnection

• Minimizes Grid Voltage Fluctuations UnderVarying Wind Conditions

Voltage RegulationLike A Conventional Power Plant

Voltage at POI

Wind Plant Power Output

Wind Plant Voltage

Average Wind Speed

Average Wind Speed

Generator

Transformer

MainTransformer

45 mi.34.5kV

POI

ConverterControl WFMS

Wind Turbine

kW

kVAR

kW

kVAR230kV

Substation

9

GE WindRIDE-THRU Offerings

0

20

40

60

80

100

120

140

-1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

Time (seconds)

Volta

ge a

t Poi

nt o

f In

terc

onne

ctio

n (P

erce

nt)

200 ms

LVRT

ZVRT

HVRT

Synchronous generator swings dramatically

• Remains on-line and feeds reactive power through system disturbances

• Meets present and emerging grid requirement with Low/Zero Voltage Ride Through (LVRT/ZVRT) capability

• Meets transmission reliability standards similar to thermal generators

Fault Recovery• Voltage recovery better than

conventional generator

Voltage Ride - Through Capabilities

Power recovers to pre -disturbance level in <200ms

Medium voltage bus drops to 0.0

Voltage Level

3-Phase, 200ms, Zero Voltage Faultfrom WINDTEST report WT5491/06

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Active Power ControlsTypical Grid Requirements

• Ramp rates• Power curtailment• Power droop w/ frequency

0.000

0.200

0.400

0.600

0.800

1.000

1.200

Available Power

Actual Power

Curtailment Example

Power Droop Test

2% Frequency Increase

50% Power Reduction

Pow

er (k

W)

Freq

uenc

y (H

z)

Pavail

PoutRamp Rate

Pow

er

Power Ramp Rates

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Future Challenges and Directions

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High Penetration Grid Dispatchability

Water Desalination

LMS 100 Gas Turbine

Wind Plant Controls(GEWE WindControls )

Grid Controls(NRPS XA/21)

Wind Farm

WFMS ControllerWFMS ControllerWFMS Controller

Wind Plant…• Coordination with grid controls• Effective use of forecasting

+ Balancing Generation…• Highly maneuverable• Fast start/stop• Good heat rates at partial load

+ Energy Storage Technologies…• Variable speed pumped hydro• Compressed Air, Batteries, Flywheels

+ Load Participation • Create new loads during low load/high

wind periods such as water desalination/purification

Wind Plant…• Coordination with grid controls• Effective use of forecasting

+ Balancing Generation…• Highly maneuverable• Fast start/stop• Good heat rates at partial load

+ Energy Storage Technologies…• Variable speed pumped hydro• Compressed Air, Batteries, Flywheels

+ Load Participation • Create new loads during low load/high

wind periods such as water desalination/purification

Water Desalination

LMS 100 Gas Turbine

Wind Plant Controls(GEWE WindControls )

Grid Controls(NRPS XA/21)

Wind Farm

WFMS ControllerWFMS ControllerWFMS ControllerWFMS ControllerWFMS ControllerWFMS Controller

Electric Vehicles

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•Current Wind Turbines

– 690 V electrical system

- Significant Cabling Weight/Cost

- Large filters

•High frequency, High voltage conversion

- lighter cables

- big benefit in offshore applications

- need HV SiC devices?

Power Conversion: Migration to Higher Voltage

Present Future?

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Offshoreconverter

station

On-shoreconverter

station

AC collectorsystem

DCcable On-shore

converterstation

DCcable

DC collectorsystem

• Reduce power conversion steps

• Higher efficiency + Lower cost

• Technical challenges : Power Electronics, Insulation, Protection

Present Future?

Power Conversion: DC interface for offshore wind

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Enabling Technologies- Advanced Power Semiconductors & Passives

SiC Module, 10 kV, 120 amps (Cree,Powerex)Conduction drop < 6 V; Switching time < 100 ns

Si IGBT assembly, 10 kV, 120 ampsConduction drop > 12 V, Switching time > 2 s

220 kVA, 60 Hzdry-type xfmr

250 kVA, 20 kHz transformers (IAP, LANL)

HPE Program

DARPA/ONR HPE program: 10 kV Silicon Carbide MOSFETs, 20 kHz Magnetics ARPA-e ADEPT program: on-going program for 15kV IGBTs, …

Can enable -> More Efficient & Reliable, Compact Power Electronic Interface for Renewables!

• Tremendous control flexibility through power electronics – goal should be for a grid that is morestable with renewable energy sources

• EVs/ PHEVs .. potentially radical impact on the grid

• Great challenges & opportunities in grid integration of renewables and new loads through power electronics

Looking Ahead