Adaptive inertia control strategy of asynchronous sending system based on coordination between DFIG and HVDC frequency limit controller

•Virtual inertia control is added to FLC.•Fuzzy control is introduced to adjust the parameters of virtual inertia control for DFIG and HVDC system.•The dead zone of FLC is used as the boundary to coordinate the control of DFIG and HVDC system.•The strategy reduces the secondary frequency disturbance caused by DFIG speed recovery. In a highly proportional hydropower asynchronous sending grid, the system is in a low damping state at all times because of the dual influence of the highly proportional hydropower water hammer effect and highly proportional DC outgoing rigid load, making frequency stability control difficult. In this study, an adaptive inertia control strategy for an asynchronous sending system based on the coordination of the wind turbine and high-voltage direct current (HVDC) frequency limiter controller (FLC) is proposed for a highly proportional hydropower asynchronous sending grid with a double-fed induction generator as the research object. The wind turbine and HVDC system provide virtual inertia support inside and outside the dead zone of FLC, respectively, and the additional virtual inertia-controlled FLC provides a fast response to the instantaneous power dip caused by wind turbine speed recovery. In addition, fuzzy control is introduced in the inertia control link of the wind turbine and FLC to dynamically adjust the virtual inertia adjustment coefficients of the wind turbine and HVDC system in accordance with the system frequency state to further enhance the coordination of frequency control. The effectiveness of the strategy is verified in a three-machine, single-return, DC outgoing system model.