Research on Fault Ride Through Control Strategy of Wind Farm via MMC-HVDC Networking System.

Large-scale long-distance grid connection of wind farms has problems such as high line losses and small transmission capacity. The use of modular multilevel flexible direct current transmission (MMC-HVDC) for power transmission is an effective solution. And the recovery of system safety and stability under fault conditions is a hot spot for research. For the problem of DC bus voltage rise caused by symmetrical faults on the grid side, the AC voltage step-down method of the wind farm side converter station (WFMMC) is used for coordinated control with the self-regulating energy-consuming circuit. The capacity required for the self-regulating dissipation resistor is reduced while ensuring that the wind farm networked MMC-HVDC system can traverse the fault stably and smoothly; And the controller for suppressing negative sequence current is designed to effectively mitigate the three-phase current imbalance caused by asymmetric faults occurring on the grid side. The active power is transferred to the grid side while protecting the switching devices from damage. Finally, the correctness and effectiveness of the proposed scheme are verified in the PSCAD/EMTDC simulation software. [ABSTRACT FROM AUTHOR]