Ferroresonance Overvoltage Mitigation Using STATCOM for Grid-connected Wind Energy Conversion Systems

We present the ferroresonance overvoltage mitigation concerning the power systems of the grid-connected wind energy conversion systems. WECS is considered based on a doubly-fed induction generator (DFIG) type. Ferroresonance over-voltage associated with a single-pole outage of the line breaker is mitigated by fast regulating the reactive power (injected/absorbed) using the static compensator (STATCOM). STATCOM controller is introduced, in which two incorporated proportion-al-integral(PI) controllers are optimally tuned using a modified flower pollination algorithm (MFPA) as an optimization technique. To show the capability of the proposed STATCOM controller in mitigating the ferroresonance overvoltage, two test cases are introduced, which are based on the interconnection status of the power transformer used within the grid-connected DFIGs. The results show that the power transformers servicing the wind farms can be under the ferroresonance stress although the transformer terminals are interconnected, and no side of the transformer is isolated. Furthermore, as a mitigation method of ferroresonance overvoltage, the proposed STATCOM succeeds in improving the system voltage profile and speed profile of the wind turbine as well as protecting the system components against the ferroresonance overvoltage.