Modified DFIG control strategy for wind energy applications

A detailed computer simulation for interconnecting wind energy system to an electric utility is presented. The proposed system consists of four high rating wind turbines each one uses double fed induction generator (DFIG). Two back to back bidirectional PWM inverters are used in the rotor circuit of each DFIG to be interfaced with the electrical utility. The simulation incorporates a flexible independent control for the active and reactive powers by using field oriented control technique. Also it introduces an effective technique to track the maximum power point of the wind energy by controlling the pitch angle and rotational speed. Active power is controlled through the direct axis current of the rotor side converter in outer control layer. Reactive power is controlled by the quadrature axis current of the rotor side converter. The system shows a stable operation under different operating conditions.