Piecewise Calculation Method for Inflow Wind Speed Based on Integration of Wind Turbine Pitch Angle and Power

Many wind farms currently host turbines approaching their designed lifespan, which need to be repowered. Using historical operational data for wind resource evaluation can not only reduce costs but also improve efficiency. However, nacelle wind speed deviates from actual inflow wind speed due to rotor disturbance, thus demanding correction prior to use. This paper innovatively proposes a piecewise inflow wind speed calculation (PMCP) method based on pitch angle and power fusion. This method divides the full wind speed range into low and high regions by taking the rated wind speed as the boundary. Inflow wind speed in the low region is calculated via the turbine’s theoretical power curve, while that in the high region is derived from the pitch angle curve, with statistical methods establishing the mathematical relationship between inflow and nacelle wind speeds. Two wind farms are selected as cases to verify the method’s applicability across different topographies. Results show that the PMCP method exhibits varying performance in different terrains. In flat terrain, the time-series wind speed RMSE is 15.7% lower than that of direct nacelle wind speed, with accuracy comparable to the IEC nacelle transfer function (NTF) method. Moreover, the Weibull distribution curve of the calculated wind speed agrees significantly better with the measured one. In complex terrain, while its error is slightly higher than the NTF method, the accuracy is still markedly improved compared to direct use of nacelle wind speed. The PMCP method can accurately calculate full-range time-series inflow wind speed and improve the accuracy of wind resource assessment at turbine sites, while boasting the prominent advantage of relying solely on historical turbine operation data with no need for measured inflow wind speed.