Power De-Loading Method for Wind Turbine Considering Rotor Speed Safety in Suppressing Frequency Fluctuation

As wind power penetration rises, the equivalent rotational inertia and frequency regulation capability of the power system decrease, resulting in intensified frequency fluctuations that threaten the frequency stability. Wind turbines need to provide frequency support and suppress frequency fluctuations. During the frequency adjustment process, the rotor rotational speed of the wind turbine set also undergoes random fluctuations. However, existing methods for reserving frequency regulation resources in wind turbines have issues in maintaining rotor speed safety. This paper proposes a method for reserving frequency regulation resources to ensure rotational speed safety in scenarios with frequency fluctuations. Specifically, based on the method of set aside power reserve through coordinated de-loading method of over-speed and pitch angle control, this paper proposes a coordinated de-loading method that modifies the initiation rotational speed reference of pitch angle control. Utilizing the theory of random signal analysis, the paper analyzes the fluctuation range of wind turbine rotational speeds during frequency fluctuation suppression, employing indicators like variance. Based on this analysis, the safety margin requirements for wind turbine rotational speed are identified, and the initiation rotational speed reference of pitch angle control is set accordingly. Finally, a simulation model is built in Simulink, and the results demonstrate that the fluctuation range of wind turbine rotational speeds under the proposed coordinated control method remains within a safe range, thereby solving the problem of maintaining rotor rotational speed safety when wind turbines encounter fluctuating scenarios.