Advanced active power filter for renewable energy applications of stand-alone induction generator

This paper presents a hybrid excitation system, consisting of a capacitor bank with a small-scale active power filter (APF), to regulate the output voltage of the stand-alone induction generator (IG) by controlling its reactive current component and to filter the harmonic currents generated by a non-linear diode rectifier load. Moreover, a deadbeat current control structure for pulse-width modulation (PWM) APF connected to a stand-alone (IG) working with variable speed and different types of loads is proposed. Sensorless control of the IG, meaning vector control without voltage sensor and mechanical shaft sensor, is considered to regulate both the IG line-to-line voltage and the DC-bus voltage of the PWM APF. In the proposed system a new designed phase locked loop (PLL) circuit is used to determine the stator voltage vector position of the IG. A 2.2 kW laboratory prototype has been built to confirm the feasibility of the proposed method. The measurement results validate the proposed power generating system with the deadbeat current controller as a good application for the IG to reduce the required number of sensors