Dual protection control method for mono-polar blocking fault in renewable energy bases transmitted by VSC-HVDC

Mono-polar blocking is a prevalent fault in DC systems that poses significant risks to the safe and stable operation of power grids. To mitigate the limitations of existing control strategies, particularly their reliability during communication system failures, this paper presents a dual protection control method specifically designed for mono-polar blocking faults. The proposed method integrates two protective strategies: primary protection and backup protection. The primary protection strategy relies on communication-based control mechanisms, while the backup protection strategy utilizes frequency signal-based controls. This comprehensive approach effectively addresses extreme scenarios, including communication system failures, thereby providing robust dual protection for the sending-end converter station during mono-polar blocking events and significantly enhancing overall protection reliability.