直流保护策略对特高压换流站过电压与绝缘配合影响的仿真分析

Simulation Analysis of Influence of DC Protection on the Overvoltage and Insulation Coordination of UHVDC Converter Stations

特高压直流换流站作为特高压直流输电工程的枢纽,其绝缘配合方案对工程的技术经济性能影响较大。为研究特高压直流换流站绝缘配合研究中出现的直流系统保护策略对换流站过电压与避雷器配置的影响,基于PSCAD/EMTDC电磁暂态仿真程序建立了糯扎渡电站送电广东±800kV直流输电工程的直流暂态过电压仿真模型,仿真分析了高端换流变YY阀侧接地和接地极线或金属回线接地故障下直流保护策略对直流暂态过电压和避雷器应力的影响。研究结果表明,直流系统保护策略对换流站绝缘配合有较大影响,糯扎渡电站送电广东±800kV直流输电工程换流站中性母线避雷器配置方式或直流保护策略需要在云南至广东±800kV特高压直流输电工程基础上进行改进。工程中若不能减小换流器直流差动保护和中性母线过电压保护的延迟时间,则建议增加中性母线避雷器E1H和E2H的并联台数以满足设计要求。

The insulation co-ordination of the converter station is important for the security and economy of the ultra-high voltage DC（UHVDC） transmission system.We studied the influence of two kinds of DC protection on DC transient overvoltage and insulation coordination of a ±800 kV converter station,such as converter DC differential protection and electrode open circuit protection.Moreover,we established a simulation model of the DC transient overvoltage of Nuozhadu power plant to Guangdong ±800 kV UHVDC power transmission project based on PSCAD/EMTDC program so as to analyze the influence of these two kinds of DC protection on the insulation coordination.The simulation results show that the influence of these two kinds of DC protection on the insulation coordination is remarkable,and the DC protection and insulation coordination scheme of the converter station in Nuozhadu power plant to Guangdong ±800 kV UHVDC power transmission project should be improved based on the Yunnan to Guangdong ±800 kV UHVDC power transmission project.The numbers of E1H and E2H arresters should be increased if time delay in the converter DC differential protection and neutral bus overvoltage protection cannot be decreased.