Wind Speed Estimation for PMSG-Based WECS under Power Limit Control

Availability of real-time wind speed information is important for the control of the wind energy conversion system (WECS). Conventionally, the wind speed estimation can be achieved by considering the motion equation of rotator of wind turbine. However, under the power limit control, the rotor speed easily reaches the maximum, making the wind speed estimation more difficult. In this paper, an effective estimation method of wind speed for the PMSG-based WECS under the power limit control is proposed, which approximates the nonlinear relation between the pitch angle and wind speed in the case of rotor speed reaching the maximum value. The proposed method adopts the polynomial function to describe the numerically solved relation between the pitch angle and wind speed, with considering different power limit references. As a result, the pitch angle is utilized to estimate the real wind speed when the rotor speed reaches the maximum. Finally, case studies are carried out to validate the proposed method.