Voltage- frequency controller for stand alone WECS employing permanent magnet synchronous generator

In this paper, a battery energy storage system (BESS) based voltage and frequency (VF) controller based on isolated three-leg VSC with a zig-zag transformer is proposed for stand alone power generation using a permanent magnet synchronous generator (PMSG). An isolated distributed generation (DG) system is realised using fixed pitch wind turbine. The proposed stand alone wind energy conversion system (WECS) consists of a permanent magnet synchronous generator (PMSG) driven by a wind turbine. The zig-zag transformer is used for isolation of the VF controller from the system and it provides path for the neutral current of the three-phase four-wire distribution system. The VF controller consists of IGBT (insulated gate bipolar transistor) based voltage source converter (VSC) with a battery energy storage system (BESS) at its dc link. The VF controller injects/ absorbs both active and reactive powers and also acts as a harmonic compensator and a load balancer. The proposed WECS along with its controller is modelled and its behavior is simulated using MATLAB with its Simulink and power system blockset (PSB) tool boxes.