EFFECT OF PITCH CONTROL AND POWER CONDITIONING ON POWER QUALITY OF VARIABLE SPEED WIND TURBINE GENERATORS

Variable speed wind turbine generators provide the opportunity to capture more power than fixed speed turbines. However the variable speed machine output can be variable voltage and variable frequency for fluctuating wind speeds. The quality of power output can be improved if adequate controls are incorporated in the system. The fluctuating wind generator output needs to be controlled. To this effect, one needs to study the dynamic characteristics of the combined wind generator system. Based on the dynamic performance of the system, better controls can be designed. The dynamic analysis and control of variable speed wind turbine system for transient studies are discussed in this paper. Some preliminary results using Matlab/Simulink, are presented. The wind generators can create voltage and frequency fluctuations and power surges in a weak network. The effect of some of the commonly used control techniques like blade pitch control, converter/inverters and the combination of pitch and converter/inverter control on the quality electricity obtained are discussed in this paper. 1