Advanced control of a boost AC-DC PWM rectifier for variable-speed induction generator

This paper describes simple control structures for vector controlled stand-alone induction generator (IG) used to operate under variable speeds. Different control principles, indirect vector control and deadbeat current control, are developed for a voltage source PWM converter and the three-phase variable speed squirrel-cage IG to regulate DC-link and generator voltages with newly designed phase locked loop circuit. The required reactive power for the variable speed IG is supplied by means of the PWM converter and a capacitor bank to buildup the voltage of the IG without the need for a battery and to reduce the rating of the PWM converter with the need for only three sensors and to eliminate the harmonics generated by the PWM converter as well. These proposed schemes can be used efficiently for variable speed, wind energy conversion systems. The measurements of the IG systems at various speeds and loads are given and show that these systems are capable of good AC and DC voltages regulation.