Maximum Power Point Tracking Method for PMSG-based Wind Energy Conversion Systems using Torque Observer

摘要

In order to enhance the efficiency of a wind energy conversion system (WECS), the maximum power point tracking (MPPT) algorithm is usually employed. This paper presents an optimal algorithm to extract the maximum available power under a sudden wind speed change condition, which is applied in a permanent magnet synchronous generator (PMSG)-based WECS. The proposed method provides a good tracking performance by means of detecting the variation in the wind speed rapidly. In addition, the implementation does not require the prior information on the wind turbine parameters, air density, or wind speed. By investigating the change directions of the mechanical output power of wind turbine and the rotor speed of generator, the proposed MPPT algorithm is able to determine an optimal speed to achieve the maximum power point (MPP). Then, this optimal speed is set to the reference in speed control loop to force the system to operate at the MPP via a three-phase converter. Conventionally, the mechanical output power of wind turbine is calculated from the mechanical torque which is measured directly by sensor. In this paper, a disturbance observer is employed to estimate the torque for the purpose of eliminating the requirement for additional sensor in WECS. The simulation results based on the PSIM are given to demonstrate the effectiveness of the proposed method.