Grid Integration and Optimal Control For Wind Energy Conversion Systems

Abstract

In order to meet the growing power needs, with concern for economics and clean environment, wind energy is gradually gaining interest as a suitable alternative. The intermittent nature of wind needs asynchronous generator for improved power extraction efficiency and induction generator (IG) suits for such application. For grid connected operation, a Doubly Fed Induction Generator (DFIG) performs better. Wind is stochastic and to maintain safe operation in harnessing electrical power from it is the main control objective in Wind Energy Conversion System (WECS). In WECS at wind speed above rated, the pitch angle is controlled to keep the generated output fixed so also the angular speed of turbine and the frequency. Pitch angle can be varied from a minimum to a maximum value. A well-tuned controller can perform robustly satisfying desired performance. Proportional Integral Derivative (PID) controllers are popularly used controllers because of their simplicity and reasonable performance. PI controllers are commonly used in Pitch control of wind turbine to control the generator angular speed to a nominal value at above rated speed. Thus determination of optimal control gain of a controller design can be seen as an optimization problem. newline