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Dynamic Response of grid Connected Wind Turbine with DFIG during Disturbances. Abram Perdana, Ola Carlson Dept. of Electric Power Engineering Chalmers University of Technology. Jonas Persson Dept. of Electrical Engineering Royal Institute of Technology. Contents of Presentation.
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Dynamic Response of grid Connected Wind Turbine with DFIG during Disturbances Abram Perdana, Ola Carlson Dept. of Electric Power Engineering Chalmers University of Technology Jonas Persson Dept. of Electrical Engineering Royal Institute of Technology
Contents of Presentation 1. Background & objectives 2. Model of WT with DFIG 3. Simulation a. Fault and no protection action b. Fault in super-synchronous operation + protection action c. Fault in sub-synchronous operation + protection action 4. Effect of saturation 5. Conclusions
Objectives Background Presentation of DFIG’s behavior during grid disturbances in different cases DFIG accounts for 50% of market share Tightened grid connection requirements immunity of DFIG to external faults is becoming an issue • Possibilities and constraints for designing fault ride through strategy safe for both WT and the grid
Generator Model Rotor Side Converter Controller Wound rotor induction generator Active power controller Saturation Reactive power controller
Turbine Model pitch angle tip-speed ratio Pitch Controller
Drive-train Model Grid Model
Rfault = 0.05 pu Avg. wind speed = 7.5 m/s Case 1: Small disturbance, no protection action
stator current rotor current terminal voltage active & reactive power turbine & generator speed Case 1: Small disturbance, no protection action
Rfault = 0.01 pu Avg. wind speed = 11 m/s Case 2: Protection action during super-synchronous speed
Sequence: • A. Fault occurs • B. If ir > 1.5 pu: • converter is blocked & rotor is short-circuited C. Generator is disconnected D. Fault is cleared Case 2: Protection action during super-synchronous speed
terminal voltage stator current Insertion of external rotor resistance active power reactive power Case 2: Protection action during super-synchronous speed
no disconnection disconnection + acting of pitch angle generator & turbine speed generator & turbine speed pitch angle Case 2: Protection action during super-synchronous speed
Rfault = 0.01 pu Avg. wind speed = 9 m/s Case 3: Protection action during sub-synchronous speed
terminal voltage stator current turbine & generator speed active power reactive power Case 3: Protection action during sub-synchronous speed
saturation curve stator current rotor current Effect of Saturation in the Model
Conclusions • DFIG provides a better terminal voltage recovery compared to SCIG during (small) disturbance when no converter blocking occurs, • for severe voltage dips DFIG will be disconnected from the grid (with conventional strategy) • converter blocking during super-synchronous operation causes high reactive power consumption, • converter blocking during sub-synchronous operation causes highreactive and active power absorption and abrupt change of rotor speed • Saturation model predicts higher value of stator & rotor currents, therefore it is important to include in designing protection