1SINTEF Energy Research

Fault ride-through testing of wind turbines

Presented by: Olve Mo

Paper co-authors: John Olav TandeLeif WarlandKjell Ljøkelsøy

SINTEF Energy Research, Norway

2SINTEF Energy Research

Background

Grid codes now require wind farms to ride-through temporarily grid voltage dips (faults).

Full scale tests against different grid codes is not practical

IEC 61400-21 ed2 (CD 2006) presents a standardized test for characterizing the wind turbine response to a voltage dip

The result of the standardized tests can be used to validate a numerical simulation model of the wind turbine.

The validated simulation model can then to be used to check compliance to different grid codes

3SINTEF Energy Research

Scope

Can numerical simulations models be used to accurately predict ride-through capabilities of a fixed speed, direct connected induction generators?

Will the results of the new standardized test provide useful results for validation of such models?

4SINTEF Energy Research

Voltage shape Type of fault Generator production

20% power Three phase

100% power

20% power

U

t

400ms

90%

Two phase

100% power

20% power Three phase

100% power

20% power

U

t

400ms

50%

Two phase

100% power

IEC 61400-21 ed2 (CD 2006)

5SINTEF Energy Research

Laboratory test setupGenerator Motor

Thyristor stack(short circuit)

IG

400V50Hz AC

AC

400V50Hz

Short circuitemulator

Wind turbineemulator

55kW Torque command

6SINTEF Energy Research

4.1 4.15 4.2 4.25 4.3 4.35 4.4 4.45 4.5 4.55 4.60

50

100

150

200

250U rms

Short circuit emulator only (IG discon.)

4.1 4.15 4.2 4.25 4.3 4.35 4.4 4.45 4.5 4.55 4.6-400

-300

-200

-100

0

100

200

300

400

Ugen1

Ugen2Ugen3

3.7 3.75 3.8 3.85 3.9 3.95 4 4.05 4.1 4.15 4.20

50

100

150

200

250U rms

3.7 3.75 3.8 3.85 3.9 3.95 4 4.05 4.1 4.15 4.2-400

-300

-200

-100

0

100

200

300

400Ugen1

Ugen2Ugen3

Instantaneousvoltage

Fundamentalpositive

sequencevoltage

Small dip setup Large dip setup

55%90%

7SINTEF Energy Research

Numerical simulation model

Model of laboratory set-up

PSCAD/EMTDC Simulation tool (Instantaneous value, time domain simulation tool)

Standard PSCAD induction machine model used (7th order model)

8SINTEF Energy Research

5.9 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.90

50

100

150

200

250

U rms measureed

U rms simulated

5.9 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.90

20

40

60

80

100

120

140

160

180

I rms measured

I rms simulated

5.9 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9

-7

-6

-5

-4

-3

-2

-1

0x 10

4

P [W] measured

P [W] simulated

5.9 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.90

1

2

3

4

5

6

7

8

9x 10

4

Q [VAr] measured

Q [VAr] simulated

Comparison (small dip, ride through succeeded)

Fundamentalpositive

sequence

Voltage

Current

Active power

Reactive power

--- Measured--- Simulated

9SINTEF Energy Research

5.5 5.6 5.7 5.8 5.9 6 6.1 6.2 6.3 6.4 6.50

50

100

150

200

250

U rms measureed

U rms simulated

5.5 5.6 5.7 5.8 5.9 6 6.1 6.2 6.3 6.4 6.50

50

100

150

200

250

I rms measured

I rms simulated

5.5 5.6 5.7 5.8 5.9 6 6.1 6.2 6.3 6.4 6.5-7

-6

-5

-4

-3

-2

-1

0

1x 10

4

P [W] measured

P [W] simulated

5.5 5.6 5.7 5.8 5.9 6 6.1 6.2 6.3 6.4 6.5-2

-1

0

1

2

3

4

5

6

7

8x 10

4

Q [VAr] measured

Q [VAr] simulated

Comparison (large dip, ride through failed)

Fundamentalpositive

sequence

Voltage

Current

Active power

Reactive power

--- Measured--- Simulated

10SINTEF Energy Research

Determination of ride-through limit

Reapplied large voltage dip with successively reduced torque setting until the generator was able to ride-through the voltage dip:

Very promising result for the use of simulations to assess fault ride through capabilities !

Turbine torque / generator production prior and during fault

Simulation Laboratory

100% Ride-through fails Ride-through fails 87.5% Ride-through fails Ride-through fails 86% Ride-through succeeds Ride-through succeeds

11SINTEF Energy Research

Large dip, 86% torque (ride through succeeded)

Large dip, 87.5% torque (ride through failed)

4.5 4.7 4.9 5.1 5.3 5.5 5.7 5.9 60

50

100

150

200

250

I rms measured

I rms simulated

4.5 4.7 4.9 5.1 5.3 5.5 5.7 5.9 60

50

100

150

200

250U rms measureed

U rms simulated

4.2 4.4 4.6 4.8 5 5.2 5.4 5.60

50

100

150

200

250

U rms measureed

U rms simulated

4.2 4.4 4.6 4.8 5 5.2 5.4 5.60

50

100

150

200

250

I rms measured

I rms simulated

Fundamentalpositive

sequence Current

Voltage

--- Measured--- Simulated

Voltage

Current

12SINTEF Energy Research

Conclusions

Simulations and laboratory measurements shows excellent agreement

Validated simulation models can accurately predict fault ride-through capability of direct grid connected induction generators

Test results from a standard test will be useful for model validation provided detailed data of both wind turbine and test equivalent are found in the test report.

More advanced wind turbines may be more challenging (doubly fed induction generator, power electronic converter control, fast pitch systems, fast acting digital protection systems)

Is it possible to get desired accuracy using simpler phasor type models ?? (e.g. PSSE)