The system will effectively isolate DC short-circuit and will restore it within a very short period of time, where switching on/off of single converter station is enabled to enhance the reliability and availability of the whole VSC HVDC.

In June-2014, Zhoushan multi-terminal VSC-HVDC project was officially commissioned by NR as the world’s first five-terminal VSC-HVDC transmission project with voltage level of ±200kV. The connection establishes an important link between the mainland and isolated islands, enabling power flows and enhancing grid reliability and security of electricity supplies between Zhoushan and its associated islands. NR supplied the VSC-HVDC valves and DC electronic CTs/VTs for three conversion stations along with the control and protection system for all the conversion stations. In the following two years, to conduct detailed system analysis and study fast fault recovery system, NR built an electromagnetic transient simulation system comprising of AC system, VSC-HVDC valves, bridge dampers, control & protection system, resonant DC switch. Based on the analysis results, NR successfully introduces resonant DC switch solution with patented high reliable bridge damper for VSC-HVDC application.

NR’s fast fault recovery system is suitable for large capacity VSC-HVDC transmission via overhead lines and DC connection networks. Its application provides theoretical base and practical experience for future VSC-HVDC development in long-distance overhead lines across the world. As a power stability expert, NR holds the key FACTS & HVDC system solution to take off your power transmission needs.