特高压工程高抗中性点绝缘水平及小电抗选择

Choice of Neutral Inductance and Insulation Level of Shunt Reactor Neutral Point in UHV AC Pilot Project

为限制1000kV输电线路在各种运行方式下的潜供电流和恢复电压,必须正确地选择中性点小电抗的参数和高压并联电抗器中性点的绝缘水平。中性点小电抗的参数应根据全容量补偿的条件确定,根据实测的线路参数和线路高抗参数计算了小电抗的参数,建议调整4台小电抗的抽头,以便取得限制潜供电流和恢复电压的最佳效果。并联电杭器中性点和中性点小电杭的绝缘水平主要决定于出现在小电抗上的最大工频电压,补偿度愈大,电抗器端部对地的零序电压愈小,则并联电抗器中性点和小电抗相应的绝缘水平愈低。通过工频过电压分析和特高压试验示范工程系统调试期间实测数据的分析,根据2次单相人工接地试验和单开关空载运行单相偷跳的试验结果校核了高抗中性点及小电抗绝缘水平,可供后续特高压交流工程参考。

The values of secondary arc current and recovery voltage of 1000 kV transmission line on different operation mode and different transmission line compensation can be restricted by right choice of neutral inductance and the insulation level of shunt reactor neutral point. The parameters of the neutral inductance of three-phase reactors should be determined according to the full capacity of the reactors. The parameters of neutral inductance can be calculated according to the transmission line parameters and the shunt reactor parameters. It is suggested that the tapping point of neutral inductance should be adjusted in order to decrease the secondary arc current and the recovery voltage. The insulation level of shunt reactor neutral point and neutral reactor is determined mainly by the power frequency over voltage on the neutral reactor. The higher the degree of compensation is and the lower the zero-sequence voltage appeared in the reactor terminal is, the smaller the values of the neutral reactor and the corresponding insulation levels are. The insulation level of shunt reactor neutral point and the neutral inductance is checked by the analysis results of the power frequency over-voltage and the actually measured data during the UHV AC pilot project system debug. The testing data mainly comes from the artificial single phase to ground tests and the one phase of the switch open test.