A comparison study between two sliding mode based controls for voltage sag mitigation in grid connected wind turbines

This paper deals with power quality restoration in grid-connected wind turbines subject to voltage sags. Since traditional voltage sag approaches cannot compensate for deep voltage sags, we design two sliding mode based voltage mitigation schemes for the rotor side converter of a DFIG-based wind turbine: an Integral Terminal Sliding Mode Control (ITSMC) and a standard SMC (SSMC). A detailed comparison study illustrating the performance of both methods is carried out under varying sag conditions. The methods are compared in terms of their ability to compensate for voltage sags and restore power quality when such faults occur. While the design aims at mitigating voltage sags with varying depths, a special focus is attributed to deep voltage sags since they represent the most frequent and costly power quality problem in DFIG-based wind turbines.