CONTROL STRATEGY OF PERMANENT MAGNET SYNCHRONOUS GENERATOR BASED STAND-ALONE WIND ENERGY CONVERSION SYSTEM

Abstract

Energy serves as the backbone for any progress. The present energy need heavily relies on the conventional sources. But, looking at the present trend it is calculated that the existing fossil fuel reserves are going to get exhausted within a few decades. Therefore, the conventional sources are being replaced by renewable sources to meet the ever increasing energy demand. Of the available alternatives, wind energy has emerged as one of the most established technologies. Nevertheless, the output of wind energy system (WECS) is dependent on wind flow which by nature is erratic and unpredictable. So far development of control scheme and ensuring a reliable WECS has been a major area of focus. The proposed system presents control strategy for the operation of a variable speed stand-alone wind turbine with a permanent magnet synchronous generator (PMSG). The PMSG is connected to a three phase resistive load through a switch mode rectifier and a voltage source inverter. Control of the generator side converter is used to achieve maximum power extraction from the available wind power. Control of the DC-DC bidirectional buck-boost converter, which is connected between batteries bank and DC-link voltage, is used to maintain the DC-link voltage at a constant value. It is also used to make the batteries bank stores the surplus of wind energy and supplies this energy to the load during a - wind power shortage. The load side voltage source inverter uses SPWM technique to convert the constant voltage generated to provide three phase sinusoidal output. The control strategy has been testeds under different wind speed variation as well as with variable load. Extensive simulation results have been performed using MATLAB/SIMULINK. Also, the hardware prototype of the proposed system has been tested.