Transient Stability Enhancement of DFIG based Wind Generator by Switching Frequency Control Strategy with Parallel Resonance Fault Current Limiter

Abstract

Doubly fed induction generator (DFIG) based wind turbine generation system is generally sensitive to the grid faults as its stator windings are directly connected to the grid. As the wind power penetration to the grid increases day by day, a complete shutdown of a large wind farm is not supported and continuity of power supply during grid faults according to the grid codes is very important. So, it is essential to improve the transient stability of DFIG based wind generation system. This paper investigates the impact of increasing the switching frequency of power converters of DFIG during fault conditions, and this switching frequency control (SFC) strategy is conjugated with parallel resonance fault current limiter (PRFCL) to enhance the fault ride through (FRT) of DFIG. It is found that the proposed SFC strategy with PRFCL (SFC-PRFCL) is a very effective mean to augment the FRT capability. To check the effectiveness of that SFC-PRFCL, its performance is compared with the bridge type fault current limiter (BFCL)[3] and PRFCL [30]. Simulations were carried out using the PSCAD/EMTDC software. Both symmetrical and asymmetrical faults are considered here to check the transient responses.