Experimental validation of a DFIG based current harmonics mitigation technique

In this paper, a harmonic mitigation technique is introduced to the doubly fed induction generator (DFIG) based wind energy conversion system (WECS) by modifying its grid side converter (GSC) classical control. When this technique implemented, the DFIG's GSC acts like an active power filter, which compensates for current harmonics generated by a nonlinear load connected to the point of common coupling (PCC), in addition to its primary purposes which are maintaining the dc-link voltage constant and ensuring unity power factor operation with the grid. This technique is simple, easy to be integrated with the existing system, and has the ability to compensate for the current harmonics even if the generator is in brake mode. Moreover, a robust control method is applied to DFIG's rotor side converter (RSC) to verify that the proposed technique does not affect the DFIG system nominal operation. Experimental results show that the proposed DFIG technique reduces the current total harmonic distortion (THD) at PCC.