Zhoushan project is the world's first five-terminal VSC – HVDC transmission system. This project consists of five converter stations and the DC high-voltage transmission lines between stations which can realize a more flexible and fast transmission mode. When the communication side failure occurs, the multi-terminal VSC- HVDC transmission system can be cut off by the fault converter station to achieve the new stable operation state.
Power and voltage coordination control technology between multi-terminal converter stations realizes the flexible deployment.
Through multi-terminal DC topological structure, the optimized overall technical and economic indexes of the project are realized；at the same time，achieving the most cost saving investment and operation of the engineering converter station and the cable lines.
Based on Multi-terminal system operation mode, control and protection strategy, NR put forward VSC-HVDC system fault analysis method and the analytic mathematical modeling under different time scales, solving the fault isolation and keeping the stability of power system;
Solving the grid-connected problem caused by intermittent energy such as wind energy, and the system insulation and connected problem caused by multi- terminal power system, etc.
The project depends on NR pioneering "PCS - 8100 VSC-HVDC fast recovery system" technology, effectively make breakthrough in rapid fault isolation and restart, and achieving single converter station flexible operation, enhancing reliability and availability for zhoushan VSC-HVDC five-terminal system.
Considering the request of zhoushan project, NR finished VSC-HVDC system analysis and research including fast recovery system, establish electromagnetic transient simulation model with AC system and DC converter valve, bridge arm type damper, control and protection system, resonant DC switch and other equipment. We complete system analysis and design in detail, based on the system research conclusion, developed a high reliability, high performance of the bridge arm damper, put forward the considerate solution for VSC-HVDC project.