Wind turbine constant voltage controller using modified SHEPWM technique

Abstract

The major challenges in designing the controller for wind turbine are fluctuations of the wind speed and the harmonic contents of the output voltage. The fluctuations of the wind turbine speed results in inconsistency of voltage supplied to the inverter which will affect the harmonic of the output voltage. Therefore, this research is dedicated to design a controller consists of a DC/DC boost converter and a DC/AC inverter integrated with the wind turbine system. The controller plays two important roles. Firstly, the controller has to control the consistency of the output voltage of the DC/DC boost converter irrespective of the inconsistency of the input voltage supplied using PI controller. Second, the controller has to generate the firing angles that giving out lesser harmonic to the single phase DC/AC inverter using the Selective Harmonic Elimination Pulse Width Modulation (SHEPWM) switching strategy. The overall system has been designed successfully using MATLAB Simulink software and implemented using real hardware. The results from both simulation and hardware are collected, analysed and compared. For boost converter, the output voltage is in constant 50V even though the input voltage supplied to the boost converter is varies and it is suitable to charge the battery system. For inverter, the hardware is tested with a resistive load and an inductive load to study the performance of the controller when dealing with different types of load. From the results obtained from simulation and hardware, it can be concluded that the designed controller circuit is working well even though the input voltage supplied to the boost converter varies and the output voltage of inverter is very low in total harmonic distortion (THD) nearly 3.6% for THD voltage and 2.1% for THD current