DFIG based wind energy conversion system for seamless operation during grid faults

Doubly Fed Induction Generator (DFIG) are widely used in wind energy generation systems because of high efficiency and independent control of active and reactive power using partial capacity converters. The proposed work concentrates on the Fault Ride Through (FRT) capability of DFIG based Wind Energy Conversion System (WECS). Here, the nine switch converter is proposed by replacing six switch converter which acts as a Grid Side Converter (GSC). The nine switch converter can provide six independent three phase output terminals. One of the three phase output terminals at the upper side are connected to the grid via interfacing inductor to realize the normal operation of GSC, while the another three phase output terminals at the lower side are connected to the neutral side of the stator windings of the DFIG to provide FRT capability. In this proposed system the control algorithms are developed to achieve the FRT capability during any kind of grid faults and to satisfy the new grid code requirements strictly. By controlling the DC link capacitor voltage, we can achieve reactive power control.