PERFORMANCE INVESTIGATIONS OF WIND ENERGY CONVERSION SYSTEM

Abstract

Operating the wind turbine at variable speed has some attractive advantages like reducing the mechanical stress in the gear box, increasing the amount of energy captured form the wind, the need for a costly blade control mechanism is avoided, improves the controllability and so integration of the wind turbines in to the grid. Generation schemes involving variable speed systems are more complicated than constant speed systems. The technological development in power electronics is making this easy. This dissertation work is oriented towards investigating the performance characteristics of a variable speed wind energy conversion system. A wind energy conversion system has been simulated with an algorithm to track peak power from wind turbine, which is independent of the turbine parameters and air density. The algorithm searches for peak power by varying the speed in desired direction. The generator is operated in the speed control mode with the speed reference being dynamically modified in accordance with the magnitude and direction of change of active power. The speed controller decides the firing angle to be given to the line-commutated inverter. The peak power points in the P- w curve correspond to dP/d w =0. This fact is made use of in optimum point search algorithm. The generator considered is a Synchronous generator, whose output is fed to controlled converter and the output from the converter is connected to grid through line-commutated inverter. An experimental setup consisting of AC-DC-AC converter set and hardware required for microprocessor control has been developed in the laboratory to test the performance characteristics. The firing pulses to the converter and line-commutated inverter are generated by using microprocessor 8085. A do motor in place of the wind turbine is used as a prime mover.