Coordinated Controller Design of Grid-connected Variable-speed Wind Energy Conversion System with Model-based Predictive Control Using Response Surface Methodology

Abstract

This paper presents an optimum design procedure for the coordinated tuning of machine side converter (MSC) and grid side converter (GSC) controllers of grid connected permanent magnet synchronous generator (PMSG). Model based predictive controller (MBPC) is used to control the MSC. MBPC based speed control design consists of two steps. A linearized state space model is employed to predict the future output (rotor speed). An optimal control law is derived by minimizing a quadratic performance index that considers the control effort and the difference between the predicted rotor speed and the reference rotor speed. A proportional-integral (PI) controller is used to control the GSC. The MSC and GSC controller parameters are determined by simultaneously optimizing the controller performance indices. The coordinated controller design is carried out in two steps. The analytical expression that relates the performance indices and the controller parameters is arrived using response surface methodology (RSM). The determination of controller parameters is posed as a constrained multi-objective optimization problem and solved employing NSGA-II (non-dominated sorted genetic algorithm II). The proposed methodology is tested on a sample power system with PMSG based WECS (Wind Energy Conversion System). Simulation results demonstrate the effectiveness of the proposed methodology.