500kV自耦变压器中性点小电抗选型分析

Analysis of Small Reactance Lectotype in 500 kV Autotransformers′ Neutral-point

针对蒙西电网部分500 kV变电站220 kV侧单相短路电流超过三相短路电流,甚至接近断路器的额定开断电流,影响电网安全稳定运行的问题,以吉兰太500 kV变电站为例,首次进行了内蒙古电网500 kV自耦变压器中性点加装小电抗降低220 kV电网单相接地短路电流的研究。分析了吉兰太500 kV变电站主变压器经不同数值小电抗接地时对220 kV电网单相接地短路电流的影响,推荐选用ZJKK-240-15型电抗器,即每组主变压器经15Ω小电抗接地,可以将220 kV母线单相接地短路电流值从48.733 kA降为43.032 kA,满足电网安全运行的要求。

For 220 kV single-phase short circuit current was over the three-phase short-circuit current, or even close to breaking capacity of circuit breaker in some West Inner Mongolia Power Grid 500 kV substations, which affected the safe and stable operation of power grid, the author took the Jilantai 500 kV substation as an example, carried out to install small reactance to the 500 kV autotransformers＇ neutral-point to reduce the 220 kV power grid single-phase grounding short circuit current. Suggest to adopt ZJKK-240-15 reactance, in which each group of the main transformer grounding by 15 ~ small reactance, and 220 kV bus single-phase grounding short circuit current can be decreased from 48.733 kA to 43.032 kA, and it can meet the requirements of safe operation of power network.