Inertia Evaluation Method of Doubly-Fed Wind Turbine Based on Improved Recursive Least Squares Algorithm

With the continuous increase in the installed capacity of renewable energy and the gradual emergence of low-inertia characteristics in the power system, developing the mechanical inertia existing in the wind turbine rotor has become an effective technical means to ensure system inertia. However, compared with synchronous machines, the mechanical inertia of the wind turbine rotor varies with the rotor speed, making it difficult to quickly and accurately assess its inertia time constant. This paper proposes a method for evaluating the inertia time constant of wind turbine based on an improved recursive least squares method: Firstly, by measuring the active power-frequency data at the point of common coupling of the wind turbine, a controlled autoregressive moving average identification model is established and the model order is determined. Secondly, based on the obtained identification model, a weighted recursive least squares identification algorithm with a forgetting factor and a deviation compensation term is designed, which can accurately identify the inertia time constant of the wind turbine. Through a simulation example established in MATLAB/Simulink, the effectiveness and accuracy of the proposed method for identifying the inertia time constant of the wind turbine are verified.