真空断路器投入并联电容器的过电压分析及防护  

Analysis and Protection Against Overvoltages Caused by Vacuum Circuit Breakers Switching on Shunt Capacitors

作　　者：魏旭 周志成 谢天喜 陶风波 刘洋 何俊佳[2] 

机构地区：[1]江苏省电力公司电力科学研究院,南京211103 [2]华中科技大学电气与电子工程学院,武汉430074

出　　处：《高电压技术》2014年第10期3193-3198,共6页High Voltage Engineering

基　　金：国家重点基础研究发展计划(973计划)(2011CB209403)~~

摘　　要：真空断路器在合闸投入并联电容器的过程中,可能会产生严重的过电压,导致相关设备损坏,国内已有多个变电站出现此类故障。为此以某110 kV事故变电站10 kV系统为对象,研究了过电压产生的原因,发现如果真空断路器在电流即将过零点时开始合闸,由于出现合闸弹跳,断口间会出现燃弧-熄弧-燃弧的现象,导致电容器上串联的电抗器与杂散电容产生谐振引发过电压,该过电压的出现随合闸时刻的不同呈现随机性。为深入研究该过电压特性,基于电力系统电磁暂态仿真软件PSCAD/EMTDC建立了真空断路器投切并联电容器过电压计算模型,分析了不同合闸时刻电压、电流波形,提出了过电压防护措施并进行了计算验证。计算结果表明,合闸时过电压幅值标幺值最高可达8,在串联电抗器侧加装避雷器可将过电压标幺值抑制在3以下(基准值为8.98 kV)。该结果证明了理论分析的正确性和防护措施的有效性,为保障真空断路器安全投入并联电容器提供了理论依据。When a vacuum circuit breaker （VCB） switches on shunt capacitor, high overvoltage may occur and harm somedevices. This situation has appeared in several substations in China. Taking a malfunction in the 10 kV power system of a110 kV substation for an example, we studied the mechanism of this overvoltage. It is concluded that when a VCB startsto close right before the moment of current zero-crossing, there will be a process of arc burning, arc extinction, and arcburning between the contacts due to the contact bounce, and this leads to the resonance between the reactor connected tothe capacitor in series and the stray capacitance and consequently to the overvoltage. Meanwhile, this overvoltage is ran-dom due to the randomness of the closing moment. To further mderstand the overvoltage, we built a model of VCBswitching on/off shunt capacitor in PSCAD/EMTDC to analyze the waveforms of overvoltage and current under variousclosing moments, and put forward and verified some protection measures. According to the simulations, the maximumovervoltage is up to 8 p.u. （8.98 kV is one unit）, and it can be reduced to 3μu. whela an arrester is installed with the shuntcapacitor in parallel. The results validate the theoretical analysis, prove the proposed protection measure to be effective,and provide a theoretical basis for ensuring VCB to switch on shunt capacitorslsafely.

关 键 词：真空断路器 并联电容器 过电压 合闸弹跳 避雷器 电磁暂态仿真 

分 类 号：TM561.2[电气工程—电器] TM53