Optimal hysteresis based DPC strategy for STATCOM to augment LVRT capability of a DFIG using a new dynamic references method

The use of grid codes to supply energy means that wind turbines must connect to grids under both normal and abnormal conditions. It is therefore necessary to implement a fast and efficient method to enable a wind turbine to safely carry through in faulty conditions. This paper employs an optimized double decouple synchronous reference frame phase locked loop (ODDSRF-PLL) to correctly detect the amplitude of grid voltage. Dynamic reactive power references are derived using a fuzzy logic controller (FLC) based on the output of ODDSRF-PLL and are fed into a hysteresis based direct power control (H-DPC). A fuzzy adaptive particle swarm optimization algorithm is used to determine the optimal bands for H-DPC to improve the performance of the static synchronous compensator (STATCOM). Besides FLC, reactive power reference correction is implemented in MATLAB and used to assign right values to reactive power references. The results demonstrate that the voltage profile is effectively improved under normal and grid fault conditions. When used with the proposed control scheme, it provides the wind generator with the ability to remain connected during voltage sags and to fulfill the demanding reactive power requirements imposed by recent grid codes.