Self-excited induction generator controlled by a VS-PWM bi-directional converter for rural applications

This paper is concerned with an application of a three-phase cage induction machine as a self-excited hydroturbine driven generator connected to the AC side of a voltage source PWM (VS-PWM) bi-directional converter. The generator is supposed to be driven by a low-head unregulated shaft hydraulic turbine. Under this condition, the range of turbine speed variation is narrower than for wind turbine driven generators. Frequency and voltage at the AC load are regulated by the action of the PWM converter. The proposed system is intended to be applied in rural plants as a low-cost source of high quality AC sinusoidal voltage with regulated frequency and amplitude. Simulation results are based on the αβγ stationary reference frame model of the induction machine using the PSpice(R) program. The experimental results report the system behavior with balanced and unbalanced, linear and nonlinear loads. The generator also presents satisfactory behavior at the start-up of an induction motor set at 66% of the system rated power