Frequency Trajectory Planning Based Transient Frequency Regulation Strategy for Wind Turbine Systems

High proportion of wind power generation weakens the power system inertia, causing concerns over frequency stability. The direct-drive permanent magnet synchronous generators-based wind turbine system (WTS) usually uses virtual inertia control (VIC) to support frequency. However, the related controller parameters are difficult to design, and the deep participation in frequency regulation (FR) will reduce the economic benefits of WTS. To this end, this paper breaks out of the VIC framework, and proposes a transient FR strategy based on frequency trajectory planning (FTP). The basic idea is to actively plan a frequency trajectory with a safety margin according to the grid frequency threshold when the system is disturbed, so that the FR power provided by the WTS can be controlled according to the planned frequency trajectory and achieve rapid support for the system transient frequency, ensuring the safe and stable operation of the grid while achieving the economy of wind power generation. Simulation and hardware-in-loop experimental results demonstrate that the proposed FTP-based transient FR strategy for WTS is effective and economical.