Analysis and control of capacitor-excited induction generators connected to a micro-grid through power electronic converters

A system consisting of a capacitor-excited induction generator (CEIG) with associated power electronic converters has been developed for supplying power to a micro-grid. The power fed to the grid from the CEIG is controlled using a diode bridge rectifier (DBR) and a pulse width modulated (PWM) inverter, connected between the generator terminals and the grid. A simple analog based hysteresis current control (HCC) technique has been employed in which the current control of the PWM inverter alone needs to be carried out by sensing the current and voltage at the grid terminals. The successful working of the system has been demonstrated for three different patterns of feeding power to a micro-grid, by experiments conducted on a three-phase 230 V, 3.7 kW CEIG, with a 100 μF delta connected excitation capacitor bank and employing the controllers fabricated in the laboratory. The grid power is represented as an equivalent load resistance in the steady-state equivalent circuit of the CEIG and the technique of genetic algorithm (GA) has been adopted for the analysis of the proposed system. The predetermined performance characteristics of the system and the results of Matlab/Simulink simulation studies have also been presented.