Current Control of the Isolated Self-Excited Induction Generator using Shunt Active Filter

The Self Excited Induction Generator (SEIG) is an isolated power source whose terminal voltage and frequency are controlled by the excitation of the capacitance or the load impedance. This paper presents a method for calculating the minimum excitation capacitance using the equivalent circuit approach for analyzing the steady state operation of SEIG. A new strategy based on an active power filter (APF) for controlling the current and power quality of the self excited induction generator (SEIG) is also presented in this paper. The shunt active power filter was implemented using a three phase PWM current controlled voltage source inverter (VSI) and connected to the wind generator and loads in order to compensate the current harmonics and reactive power. The PWM-VSI gate control signals are derived from hysteresis band current controller. The proposed active filter proved to play an important role and give good dynamic response and robust behavior upon changes in load parameters. This investigation demonstrated that power average control strategy can facilitate the improvement of the power quality. The proposed control method extracts fundamental (reference) components of the source current for the shunt active power line conditioners for nonlinear and unbalanced loads. The Power average approach additionally maintains the voltage of the capacitor (of the PWM inverter) nearly constant without any external control circuit. The shunt APF in conjunction with the proposed controller performs perfectly under different steady state and transient conditions. The simulation results with nonlinear loads and unbalanced loads have showed the effectiveness of the proposed scheme for harmonic reduction in Wind based Power Generation.