A Frequency Regulation Strategy for Wind Power Based on Limited Over-Speed De-Loading Curve Partitioning

Over the past decade, wind power has rapidly developed, bringing great challenges to power system frequency control. To enable wind turbines (WTs) to operate with independent frequency regulation similar to that of synchronous generators, the development of strategies for wind power frequency regulation has received increasing attention. Here, a frequency regulation strategy by wind power based on limited over-speed de-loading curve partitioning is proposed. On the basis of the rotor kinetic energy control, the relationship between the de-loading capacity of over-speed control and wind speed is studied. Combined with the data fitting, the limited over-speed de-loading level curve of the WT is obtained to partition over-speed de-loading and pitch de-loading; this approach maximizes the use of over-speed de-loading and enhances the frequency regulation capacity of the WT. Finally, based on DIgSILENT/PowerFactory software, a four-machine two-zone power system model and an IEEE-39 bus system are built, and the control effects of this control strategy under different penetration levels, different wind speeds and different de-loading levels are compared and analyzed. The simulation results show that the control strategy can effectively improve the frequency response capability of wind power systems.