Insulation Coordination For Converter Stations Of UHVDC And VSC-HVDC Transmission System

UHVDC power transmission system has the superiorities of bulk power transmission over extreme long distance with low loss.±1100kV UHVDC is a new DC voltage level that is very suitable for transporting large energy to distant load centers. Multi-terminal VSC-HVDC has many advantages compared with the conventional HVDC, it is very suitable for many special fiels such as renewalbe and distributed sourc connected to power grid, island power supply, urban power grid and asynchronous AC grid interconnection and so on. UHVDC and VSC-HVDC are the hottest topics in DC technologies, and ther are representing the frontier in the research of DC technology.The insulation coordination design for converter station is one of the key technologies of DC power transmission system, and the insulation level has a great impact to the entire costs of the project. In this paper, we study the insulation coordination of the converter station based on the±1100kV UHVDC and MMC-HVDC power transmission system.In accordance with the insulation coordination experiences of the existed±800kV UHVDC converter station, and by analyze the characteristics of±1100kV UHVDC, we proposed the arrester configuration scheme of±1100kV UHVDC converter station, and then calculated basic parameters of these arresters. Based on the arrester configuration and the system parameters of the±1100kV UHVDC project from Zhundong to Sichuan, we simulated the overvoltage for some important equipment in typical faults. Finally, we determined the insulation level for equipment in the converter station.For multi-terminal VSC-HVDC systems, there rarely have projects are put into operation up to now. To study the insulation coordination of the multi-terminal VSC-HVDC converter station, we proposed the arrester configuration scheme in accordance with the principle for conventional DC system, and then we introduced the calculation methods for arrester parameters, and calculated the overvoltage of equipment based on the Zhoushan multiterminal VSC-HVDC power transmission project. Finally, we determined the insulation level for equipment in the converter station.At last, in view of the specificity of±1100kV UHVDC and VSC-HVDC system, this paper introduced other arrester configurations, and calculated the insulation levels by each configuration. Moreover, we discussed the advantages and disvantages for each arrester configuration. These research results will provide important bases for the critical projects.