SENSORLESS MAXIMUM POWER POINT TRACKING CONTROL OF WIND ENERGY

Abstract

Wind energy is the world's fastest growing energy source, averaging 30 % growth per year. Modem turbines are likely to be producing useful power, with total capacity 94,123 MW of which India accounts for 8,000MW. Wind energy, as part of a diverse renewable energy portfolio across the country, can also make a valuable contribution to our national energy security and meet rising demand in a sustainable way. it has been recognized as an environment friendly and economically competitive means of electric power generation. Wind energy technology has experienced accelerated growth and advancement in the past decade due to increase penetration of wind power into the electricity grid. Power generation using wind energy is possible in two ways, i.e., constant speed and variable speed operation using power electronic converters. With fixed speed operation it is not possible to fully utilize the energy present in the wind, as it gives maximum efficiency only at one speed. As the source kinetic energy varies along with wind speed sufficient energy can be utilized only if the turbine is operated under variable speed mode. Variable speed system has several advantages over the fixed speed method of operating wind turbines, such as reduction of mechanical stress and increase in energy capture. In view of the above, present work dealt with the three phase grid connected variable . speed system employing a permanent magnet synchronous generator. the models are developed analytically for tracking the peak power. An algorithm was developed which is independent of turbine parameters and air density that searches for peak power by varying the rotor speed to desired point. Further a new sensorless scheme was proposed and a mathematical model has been simulated on a PC using Matlab/ Simulink software and its tool packages where the rotor speed is calculated on the flux linkage basis instead of measuring it with the help of Demultiplexer directly. It has been found that a close correlation exist between the proposed sensorless and the conventional sensored scheme in terms of transients response including the power, rotor speed, electromagnetic torque, voltage and current plots. It is expected that by the introduction of sensorless technology in the field of wind power technology the cost of the optical encoders and anemometers could be completely eliminated and overall versatility of the system could be increased. Based on the model analysis and results, it is recommended that the sensorless technology could be implemented in the existing wind energy conversion system. However accuracy of new technology should be evaluated at very low speed particularly at zero speed and the parameter variations. iv