Frequency Control of SEIG Based Microgrid during Transition from Grid Connected to Island Mode

Frequency behavior of self-excited induction generator (SEIG) wind turbines during control mode transition from grid connected to islanded mode is investigated in detail. A robust control scheme for frequency regulation based on combined action of STATCOM, energy storage system (ESS) and pitch angle control for wind powered microgrid (MG) is proposed. Suggested STATCOM controller comprises a 3-phase voltage source converter (VSC) that contains insulated gate bipolar transistors (IGBTs) based pulse width modulation (PWM) inverters along with a capacitor bank. Energy storage system control consists of current controlled voltage source converter and battery bank. The proposed model performs robust action upon detection of islanding to compensate reactive and supply active power demand thus regulating frequency at point of common coupling (PCC) with improved load stability. Obtained results reveal that proposed method control not only stabilizes frequency during transition duration but also minimizes sudden frequency imbalance caused by load variation or wind intermittencies in islanded operation. The studied system is investigated with and without proposed control schemes.