Wind power conversion based on Quasi-z source Inverter

摘要

The variable wind generator output due to unpredictable variation in wind speed is suitably controlled through a closed loop system employing the buck-boost capability of quasi z-source inverter derived from traditional z-source inverter (ZSI) and is converted into a three phase power. The quasi z-source inverter inheriting all the advantages of the traditional ZSI replaces the conventional PWM inverter in the system. Additionally, the quasi ZSI has the unique advantages of lower component ratings and continuous dc current from the source. The closed loop controller carefully monitors wind generator voltage and controls the shoot-through duty cycles of the inverter employing third harmonic injection constant boost control to develop a three phase steady boosting voltage, which is not possible by conventional PWM control. The whole system is modeled, analysed and verified through simulation and hardware arrangement. It provides the unique output voltage regulation by making an appropriate choice of boost factor under both arbitrary generator voltage and variable load conditions. The proposed closed loop system, therefore, can be used for smooth and effective dynamic and steady state control maintaining the three phase output at a desired level.