Hybrid controller for transient stability in wind generators

In wind power plants typically squirrel-cage induction generators (SCIG) tend to drain large amount of reactive power from the grid, potentially causing a drop voltage. To improve SCIG´s power quality and transient stability, this paper investigates a new pitch angle control strategy, including normal scheme and Fault-Ride-Through (FRT) scheme, based on hybrid of PI and Fuzzy logic technique. In particular, an analytic model for transient stability is implemented using the equivalent circuit of the SCIG and on the concepts of stable and unstable electrical-mechanical equilibrium. This method has been evaluated by comparing the results with the dynamic simulation. The dynamic simulation results show that the proposed hybrid controller can be effective in enhancing output power smoothness and FRT requirements for SCIG in wind power system.