1000kV交流断路器开断电流的直流分量时间常数和零偏现象

DC Component Time Constant and Zero Offset Phenomena of Breaking Current for 1000 kV Circuit Breaker

为了确定特高压断路器短路开断电流的试验直流分量时间常数,依托本期和远期1000kV晋东南-南阳-荆门示范工程,采用EMTP程序模拟计算方法,研究了影响示范工程断路器直流分量衰减时间常数和零偏现象的因素;提出了将模拟计算的直流时间常数折算至断路器试验值的计算公式;统计分析出远期示范工程三相短路直流分量时间常数折算后最长为112ms,因此建议我国特高压断路器直流分量衰减时间常数可选120ms,并得到示范工程采用。特高压断路器开断时间内电流产生零偏现象有接地短路故障、合空线、并网前单相接地和合空变4种工况,这4种工况都不会损坏断路器,可不采取装分闸电阻的应对措施。

In order to determine DC component of rated short circuit current break for UHV circuit breaker, the factors that influence DC component time constant and current zero offset are studied with EMTP simulation calculation. The simulation is based on 1000 kV Jindongnan-Nanyang-Jingmen pilot project in 2009 and in the future time 2015 when national UHV network interconnect to pilot project. This paper presents a formula to covert DC component time constant calculated by simulation into UHV circuit breaker test time constant. The statistic calculated lon gest 3 phase short circuit DC component time constant converted by the formula is 112 ms, so that it is suggested that UHV circuit breaker DC component time constant can select 120 ms and this suggestion is accepted by pilot project. In the four cases, which are 2 or 3 phases ground fault, energizing transmission line, single phase ground fault before transmission line connecting grid and transformer energizing, the current zero offset could occur during breaking time of UHV circuit breaker. The 4 cases do not damage the UHV breaker and no preventive measures should be taken, such as breaker with opening resistance.