comparison of the behaviour of wind farms and … · 05.2004 apcg /...

Comparison of the Behaviour of Wind Farms and Conventional Power

Stations during Grid Failure ConditionsDr. Martin Janßen

May 2004May 2004May 2004

APCG / 4MJA005_Wind-Farms-IEEE_13-05-2004_00EN.PPT

05.2004 APCG / 4MJA005_Wind-Farms-IEEE_13-05-2004_00EN.PPT/ Dr.JANSSEN / Be 2

Wind Farms and Conventional Power Stations during Grid Failure Conditions

Overview

� Introduction

� Grid Faults– Requirements for Grid Stability– Fault Clearance– Measurement

� Characteristics of Generating Units– Synchronous Generator– Fully Fed Synchronous Generator– Doubly Fed Induction Generator

� Simulation– Simulation Model– Simulation Results

� Conclusion



� The effect of wind power cannot be neglected anymore

� Grid operators expect wind farms to behave likeconventional synchronous generators:

– Fault Ride Trough– Voltage Control– Frequency Control

� New Grid Connection Conditions

� How do wind farms behave during grid faults?

� Does this behaviour cause any problems?

Introduction



� High short circuit current for triggering of circuit breakers

� Delivery of reactive current during the fault

� Fast recovery of active power after fault clearance

Grid Faults

Requirements for Grid Stability



� A fault on a transmission line is connected to the grid by the two ends of the line

� The circuit breakers nearest to the fault open within 100 ms

� The circuit breakers at the other end open 40 ms after the first

� The individual phases of the circuit breakers open sequentially,typically 5 ms apart

Grid Faults

Fault Clearance



Grid Faults

MeasurementTree phase fault on a 275 kV transmission line

Phase A

Phase B

Phase C

Fault Duration

80 ms

225

Phase Voltage[kV]

33.5 kV (15.8 % of Vnom)

Phases B and C see similar voltage depressions to Phase A



Characteristics of Generating Units

� High short circuit current

� Reactive current provided during grid faults

� Fast recovery of active power, but high oscillations

� Danger of tripping if fault lasts too long

Synchronous Generator




� Variable speed generator� Generator decoupled from grid, behaviour determined by the converter� Low transients� Limited short circuit current� Reactive current provided by converter� Fast recovery of active power possible

SG

Turbine

High voltageHigh voltage

Transformer ~~

Fully Fed Synchronous Generator




� Most common variable speed wind turbine design� High voltage dynamic leads to over current of the generator� High short circuit current but low a.c. component� Reactive power provided by generator and converter� Fast recovery of active power possible

DFIG

High voltageHigh voltage

Transformer

~~

Doubly Fed Induction Generator



Simulation model

Pro Wind

=~ =

~

~

TransformerHV - MV

11 % uk

iGrid

uPCC

uGen

MTurbine

Crowbar

Generator

n

ZG

ZF

uGrid

TransformerMV - LV

6 % uk



Simulation 3-Phase Fault with UPCC = 15 % UN


0

0.5

1

U /

UN

-2

0

2

4

6

I Gri d

/ IN

-1 0 1 2 3 4-4

-2

0

2

4

P, Q

/ P

N

t [s]

ia, ir / iN

P, Q / PN

UGen / UNUPCC / UN




0

0.5

1

U /

UN

-6

-4

-2

0

2

4

6

i Grid

/ iN

-0.1 0 0.1 0.2 0.3 0.4-4

-2

0

2

4

P, Q

/ P

N

t [s]


UGen / UNUPCC / UN

P, Q / PN

iGrid / iN




Fully Fed Synchronous Generator

0

0.5

1

U /

UN

-2

-1

0

1

2

i Gr id

/ iN

-1

0

1

2

I Grid

/ IN

-1 -0.9 -0.8 -0.7 -0.6 -0.5-1

0

1

2

P, Q

/ P

N

t [s]

UGen / UNUPCC / UN

iGrid / iN

P, Q / PN

ia, ir / iN




Doubly Fed Induction Generator

0

0.5

1

U /

UN

-2

0

2

i Gr id

/ iN

-2

0

2

I Grid

/ IN

-0.1 0 0.1 0.2 0.3 0.4

-2

0

2

P, Q

/ P

N

t [s]

UGen / UNUPCC / UN

iGrid / iN

P, Q / PN

ia, ir / iN




DFIG + Fully Fed SG

0

0.5

1

U /

UN

-2

0

2

i Gr id

/ iN

-2

0

2

I Grid

/ IN

-0.1 0 0.1 0.2 0.3 0.4

-2

0

2

P, Q

/ P

N

t [s]

UGen / UNUPCC / UN

iGrid / iN

P, Q / PN

ia, ir / iN



Conclusion

� Wind farms can have a similar characteristic as conventional synchronous generators

� All types of generators have different advantages / drawbacks regarding short circuit current / reactive power / active power

� With an appropriate design and control wind farms can help to stabilize the grid

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comparison of the behaviour of wind farms and … · 05.2004 apcg /...

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