Wind turbine model validation with measurements

Transcription

1 9 th Deep Sea Offshore Wind R&D Seminar, January 2012, Trondheim Wind turbine model validation with measurements - Comparison between measured and simulated responses to voltage dips in the grid Jorun Marvik (presenting) and Atsede Endegnanew, SINTEF Energy Research 1

2 Outline Background; benchmark test procedure, measurement collection Wind turbine 1 model validation results Wind turbine 2 model validation results Summary/Conclusions 2

3 Background Important to predict wind turbine responses to grid disturbances Grid codes regulate how wind turbines should respond to disturbances in the grid Compliance with grid code verified through measurements or simulations Model validation to assure that simulation results can be trusted 3

4 IEA Wind Annex 21 benchmark test procedure Required measurements: time-series of instantaneous voltage and current in all three phases measured voltages and currents are converted to fundamental, positive sequence rms values Input to simulations: voltage amplitude and phase angle time series, to controllable voltage source Validation: comparing simulated responses of active and reactive power with positive sequence active and reactive power calculated from measured voltages and currents 4

5 Measurement collection Elspec G4430/G4420 blackbox instruments continuous sampling of voltage and current in all three phases. Measurements are stored in a central database at SINTEF Energy Research Post-processing of data: by instrument software,(elspec Investigator), and by Matlab toolbox developed at SINTEF Energy Research. Elspec Investigator does not provide the phase angle Sampling rate: 51.2 khz/25.6 khz Time synchronization: GPS/SNTP Wind turbine 1: fixed speed turbine, directly connected induction generator Wind turbine 2: variable speed turbine (gearless), full-power converter interfaced synchronous generator, 5

6 Outline Background; benchmark test procedure, measurement collection Wind turbine 1 model validation results Wind turbine 2 model validation results Summary/Conclusions 6

7 Wind turbine 1 directly-connected induction generator Rating: 2.3 MVA Modelled in SIMPOW Parameters for similar turbine (generator impedances, generator and turbine inertias, shaft stiffness) known, scaled according to rating Induction generator: transient model, without saturation Capacitor bank for reactive compensation Mechanical drive train represented by a two-mass model: turbine and generator inertia with a shaft and an ideal gearbox between 7

8 Positive sequence voltage magnitude and phase angle during a voltage dip event Positive sequence voltage [pu] Phase angle [ ] U pos (a) (U pos ) -178 (b) Voltage dip down to 85 % of nominal value. Duration ~ 200 ms 8

9 Impact of changing shaft parameters Active power [pu] Active power [pu] Measurement S.: K=0.326 S.: K= Time [s] Measurement S.: D=0.1 S.: D=5 S.: D=10 0 Time [s] Good agreement in frequency of oscillations. Measured response has higher amplitude than the simulated Increased oscillation with increased damping (opposite of expected) possibly due to interaction between responses of shaft and generator 9

10 Impact of changing generator rotor parameters Active power [pu] Active power [pu] Measurement S.: R 2 = S.: R 2 =0.02 S.: R 2 = Measurement S.: X 2 =0.075 S.: X 2 =0.15 S.: X 2 = Rotor impedance impacts on frequency of oscillations 10

11 Result after tuning of shaft and generator parameters Quite good agreement between measurement and simulation can be achieved by adjusting shaft and generator parameters 11

12 Outline Background; benchmark test procedure, measurement collection Wind turbine 1 model validation results Wind turbine 2 model validation results Summary/Conclusions 12

13 Wind turbine 2 variable speed, full-power converter Rating: 2.3 MVA Modelled in SIMPOW and PSCAD No parameters known, typical/default model parameters used Synchronous generator: transient model, without saturation SIMPOW Full Power Converter Wind Turbine model described in manual. Includes wind turbine and generator model. Speed, pitch and AC-voltage control systems. PSCAD own developed converter. Generator and turbine not included in the model. 13

14 Positive sequence voltage magnitude and phase angle during a voltage dip event Positive sequence voltage [pu] U pos 0.8 (a) Phase angle [ ] (U pos ) 0 (b) Phase angle decrease in steady state: frequency of measured voltage deviates from constant reference of 50 Hz 14

15 Results from SIMPOW-simulation Active power [pu] Reactive power [pu] Simulation Measurement 0.13 (a) Simulation Measurement (b) Not very good agreement between measurement and simulation. Changing the controller parameters has limited impact Both active and reactive power goes to a new steady-state level after the dip Due to change in wind speed or due to control strategy? Simulation: constant wind speed (active power) and reactive power 15

16 Comparison with results from PSCAD-simulation Active power [pu] Reactive power [pu] Step-change applied in active and reactive power "cheating" to get a better agreement Measured Sim. PSCAD Sim. PSCAD, step-change Generator and turbine not included in PSCAD, little difference in the results between SIMPOW and PSCAD with constant set-points for P and Q 16

17 Outline Background; benchmark test procedure, measurement collection Wind turbine 1 model validation results Wind turbine 2 model validation results Summary/Conclusions 17

18 Summary/Conclusions Validation of models important to ensure that simulation results can be trusted Fixed speed wind turbine with directly-connected induction generator: quite good agreement between measured and simulated responses in active and reactive power. Better agreement could be achieved by adjusting shaft and generator parameters. Variable speed wind turbine with full-power frequency converter: response to voltage disturbance depends on converter parameters and control strategy. Hard to obtain good agreement between measurement and simulation without knowledge about the converter and corresponding control system. 18