Wind energy conversion system regulation via LMI fuzzy pole cluster approach

This paper addresses the design of fuzzy state feedback controller that has not only the ability to stabilize the fuzzy model/system but also to control the transient behavior and closed loop poles location for wind energy conversion system (WECS) that presents interesting control demands and exhibits intrinsic non-linear characteristics. The proposed fuzzy controller is employed to regulate indirectly the power flow in the grid connected WECS by regulating the DC current flows in the interconnected DC link. First, a Takagi-Sugeno fuzzy model is employed to represent the non-linear WECS. Then a model-based fuzzy controller design utilizing the concept of parallel-distributed compensation is developed. Satisfactory time response and closed loop damping over wide operating range are achieved by forcing the closed loop poles into a suitable sub-region of the complex frequency plane. Sufficient stability conditions are expressed in terms of linear matrix inequalities (LMI's) which can be solved very efficiently using convex optimization techniques. The design procedures are applied to a dynamic model of a typical wind energy conversion system to illustrate the feasibility and the effectiveness of the proposed control techniques via simulation example. (C) 2008 Elsevier B.V. All rights reserved.