800kV浙西特高压直流换流站暂态过电压研究

基于溪洛渡—浙西800 kV特高压直流输电工程,对浙西换流站的暂态过电压和各避雷器的负载进行详细仿真计算分析。在交流侧选取了交流母线三相接地、交流相间操作冲击和失交流电源3种典型故障工况;直流侧选取了最高端换流变Y/Y绕组阀侧单相接地、低压端换流变Y/Y绕组阀侧单相接地和全电压启动3种典型故障工况进行研究。分析结果表明:失交流电源是交流侧的最严酷工况,交流母线过电压771 kV,通过交流母线避雷器A的最大电流0.14 kA,最大能量2.07 MJ;最高端换流变Y/Y阀侧单相接地在换流阀两端产生过电压375 kV,通过阀避雷器V1最大电流2.32 kA,最大能量6.73 MJ;低压端换流变Y/Y阀侧单相接地,阀避雷器V3通过最大电流1.04 kA,最大能量2.84 MJ;全电压起动在直流极母线上产生1 330 kV的过电压,避雷器DB通过最大电流0.56 kA,最大能量4.35 MJ。

Study on Transient Overvoltage of Zhexi Converter Station of ±800 kV DC Power Transmission Project

The transient overvltage and load of arresters in Zhexi converter statiom for ?800 kV DC power transmission project from Xiluodu to Zhexi are simulated and analyzed in details.To carry out this research,following fault conditions are chosen: three typical faults in AC system,i.e.,three-phase ground fault of AC bus,interphase switching surge in AC system and losing AC power source,and three typical faults in DC system,i.e.,single-phase ground fault occurred at upper rectifier bridge side of wye-wye connected winding of converter transformer,single-phase ground fault occurred at lower rectifier bridge side of wye-wye connected winding of converter transformer and full-voltage starting.Research results show that the losing AC power source is the most severe fault condition of AC system,under which the overvoltage of AC bus is 771 kV,the maximum current passing through arrester of AC bus is 0.14 kA and the maximum energy entering arrester is 2.07 MJ;when single-phase ground fault occurs at upper rectifier bridge side of wye-wye connected winding of converter transformer,the overvoltage cross the rectifier bridge is 375 kV,the maiximum current passing through the valve arrester is 2.32 kA and the maiximum energy entering the arrester is 6.73 MJ;when single-phase ground fault occurs at lower rectifier bridge side of wye-wye connected winding of converter transformer,the maximum current passing through the valve arrester is 1.04 kA and the maiximum energy entering arrester is 2.84 MJ;the overvoltage appears on DC polar bus caused by full-voltage starting,is 1 330 kV,the mamimum current passing through polar bus arrester is 0.56 kA and the maximum energy entering the arrester is 4.35 MJ.