Direct power control of a DFIG-based WECS with active filter capabilities

This paper presents an integrated control strategy for a DFIG-based wind energy conversion system (WECS) with power quality enhancement capabilities. The proposed control scheme performs independent active and reactive power control of the DFIG by means of a robust direct power control (DPC) approach acting through the rotor side converter (RSC). Likewise, active filtering functionality is achieved through the grid side converter (GSC) along with a synchronous reference frame based scheme for the extraction of the compensating current components. Experimental results are presented and discussed. The implemented test rig comprises a DFIG driven by a DC motor which in turn is controlled to emulate the behavior of a wind turbine following a given wind speed profile. A back-to-back PWM-controlled power converter and C-programmed DSP control cards make-up the control system. Full control of active and reactive power is obtained and a remarkable active filtering operation is achieved even for highly unbalanced and non-linear loads.