Self-excited induction generator with simple voltage regulation scheme for wind energy

In this paper, a three-phase induction-machine-based wind power generation scheme is proposed. This scheme uses a low-cost three-phase diode bridge rectifier circuit connected to the induction machine via the AC load voltage regulator (AC-LVR) to transfer DC power with voltage regulation. The AC-LVR is used to regulate smoothly the output voltage of the three-phase self-excited induction generator (SEIG) connected to the diode bridge rectifier circuit. The excitation to the three-phase SEIG is supplied by a static VAr compensator (SVC) composed of the fixed excitation capacitor and the thyristor controlled capacitor. This simple method for obtaining a full variable-speed wind turbine system by applying a bi-directional power converter to a conventional induction generator is useful for wind power generation with a wide speed variation. The dynamic performance responses and the experimental results of a 5-kW 220-V three-phase SEIG directly connected to a three-phase diode bridge rectifier circuit at various loads are presented. Moreover, the experimental results of the PI closed-loop feedback voltage regulation scheme prove the practical effectiveness of this simple proposal for a wind turbine system.