Maximum power tracking in WECS (Wind energy conversion systems) via numerical and stochastic approaches

• The structure of a MPPT (maximum power point tracking) scheme is presented.
• The scheme is divided into the optimization algorithm and the tracking controller.
• The optimization algorithm is based on an online line search numerical algorithm.
• The tracking controller is treating the aerodynamics torque as a loop disturbance.
• The control technique is simulated with stochastic wind speed by Simulink and FAST.

This paper presents a complete design of a two-level control system to capture maximum power in wind energy conversion systems. The upper level of the proposed control system adopts a modified line search optimization algorithm to determine a setpoint for the wind turbine speed. The calculated speed setpoint corresponds to the maximum power point at given operating conditions. The speed setpoint is fed to a generalized predictive controller at the lower level of the control system. A different formulation, that treats the aerodynamic torque as a disturbance, is postulated to derive the control law. The objective is to accurately track the setpoint while keeping the control action free from unacceptably fast or frequent variations. Simulation results based on a realistic model of a 1.5 MW wind turbine confirm the superiority of the proposed control scheme to the conventional ones.