Decoupled indirect current control of DFIG for wind energy applications

Doubly Fed Induction Generators (DFIG) has emerged as a suitable alternative for conversion of wind energy to grid quality energy under varying wind conditions. Often the control mechanism use large number of sensors and employ complex computations. Moreover, the reported control schemes for DFIG employing grid side converter (GSC) do not ensure a drawl of unity power factor (upf) sinusoidal current from a.c. source for maintaining the dc bus, and PWM voltage control and often employed for the rotor side converter (RSC) to inject/draw current in/from the rotor as per wind speed to keep the frequency and voltage constant at stator terminals. The paper deals with the control of DFIG for wind energy applications using indirect current control to control RSC for regulating power flow in the rotor circuit of DFIG and to ensure upf operation of GSC. A grid connected DFIG has been considered for present study. The GSC injects the required power into the DC bus to maintain the voltage constant. The simulation studies demonstrate that the proposed technique is more effective, faster, energy efficient and utilizes lesser number of components.