PLL Synchronization Stability Analysis of MMC-Connected Wind Farms under High-Impedance AC Faults

This article analyzes the transient stability of an offshore wind farm connected via modular multilevel converter (MMC)-based high-voltage direct-current transmission system. The wind farm is composed by full-scale type-4 wind turbines, whereas short-circuit faults occurring in between the MMC and wind farm are considered. The MMC tends to be switched to the current limiting mode or the overmodula...