Maximum Power Point Tracking of Variable-Speed Wind Turbines Using Self-Tuning Fuzzy PID

Abstract

This paper designs a new controller to increase efficiency of maximum power point tracking (MPPT) at nominal wind speed based on adaptive PID controller where its coefficients are optimized using a fuzzy controller. PID controllers are widely used in linear systems due to their simple structure and proper response. Due to stochastic changes of wind speed, wind turbines generally have nonlinear nature. In addition, turbines have different dynamic structures regarding their construction conditions. Thus, using a controller which can preserve system stability considering changes of system parameters and obtain reach steady state in the shortest possible time is necessary. In this method, information adopted from wind speed and nonlinear turbine model are used to identify system using closed loop identification. In the following, Hill climbing search (HCS) algorithm is used to determine optimal operating point of the turbine in the nominal wind speed range, online. Advantage of perturb and observe (P&O) methods includes simple structure and adaptability with different stochastic and nonlinear systems. The designed controller minimizes the error between output power of the turbine and the optimized power. This controller is simulated practically on a 3KW wind turbine. Simulation results indicate efficiency and robustness of the designed controller.