Stand-alone induction generator using PWM converter and its AC and DC hybrid power applications to variable-speed renewable-energy generation

This paper describes a simple control structure and power conditioning system for indirect vector controlled stand-alone induction generator (IG) used to operate under variable speeds and different load types. The required reactive power for the IG system is supplied by means of a capacitor bank and a voltage-source PWM converter. Using a capacitor bank to transfer the reactive power to the IG under the rated speed and no-load conditions starts the IG operation and reduces the PWM converter size. The vector control structures for the variable speed IG power conditioning system compensating for changes in the electrical loads with considering the magnetizing curve of the IG is developed to regulate the DC link and AC output voltages. This proposed scheme can be used efficiently for variable speed, wind energy conversion system. The experimental and simulated performance result of an IG power conditioning system at various speeds and loads are given and show that this system are capable of good AC and DC output voltage regulation.