Enhancement of DFIG performance at high wind speed using fractional order PI controller in pitch compensation loop

Doubly fed induction generator (DFIG) has been widely applied in wind farms. Meanwhile, DFIG control at high wind speeds has become an important issue. In this regard, the main task of pitch angle control loop is too important by the wind speed increase above the middle speeds (e. g. 12 m/s) to limit DFIG active power and rotor speed and to control the machine performance. In this study, a fractional order PI controller (FOPI) is designed and applied for the pitch angle compensation control loop to improve the DFIG performance at the high wind speed of 18 m/s. Due to using the fractional order coefficient as an extra control variable in the FOPI controller function in comparison with the PI controller, a preferable control scheme would be realized in the pitch angle control by the wind speed increase to high values. In this regard, the various simulation results for monitoring the active power and rotor speed are obtained in the multi machine test system including the DFIGs considering high wind speed operating mode via using MATLAB/SIMULINK software. In addition, different kinds of transient faults are considered to evaluate the performance of the proposed FOPI controller, instead of the conventional PI controller. The results validate the advantage of using the FOPI control scheme in the pitch angle control loop for promoting the DFIG active power and rotor speed profiles.