MIXED SENSITIVITY CONTROL DESIGN AND STABILITY ANALYSIS OF BRUSHLESS DOUBLY FED INDUCTION GENERATOR

The brushless doubly-fed induction machine continues to attract increasing interest for applications in wind power generation systems and variable speed motor drives where, robustness and low servicing costs are much desirable. This paper presents an H-infinity control of a grid connected variable speed wind energy conversion system based brushless doubly-fed induction machine. For this purpose, a linearized small signals mathematical model has been developed, and the mixed sensitivity control theory has been used. To enhance the performances of the mixed sensitivity design, decoupling and integral actions have been considered. Additionally, the effect of electrical parameters uncertainties and operating speed change on the stability of the brushless doubly-fed induction machine has been given. The proposed control scheme has been investigated through simulation implementation under different modes of operation, sub-synchronous, synchronous and super-synchronous mode. The obtained results show that the controller provides satisfying performances when the operating point varies.