SF_6断路器开断能力数值预测方法研究综述

综述了SF6断路器极限开断能力以及介质开断能力的数值预测方法的最新研究进展。电流过零前200 ns的电弧电导(G200)是判断断路器热开断能力的一个重要参数,为计算G200,对电弧特性进行模拟,在燃弧阶段采用磁流体动力学模型,而在接近电流零区采用Mayr模型,从而建立相应的电路模型来确定电弧时间常数和电弧功率损耗系数等参数,以分析高压断路器的热开断能力。为判断电击穿能力,需要根据电弧过零时灭弧室内的每一点的压力和温度值,确定对应点的临界击穿场强分布Ec,同时计算在暂态恢复电压作用下灭弧室内的电场分布Ea,然后通过比较灭弧室内各处Ea和Ec的值,就可以判断出灭弧室内不同区域电击穿几率的大小。

Review of the Numerical Prediction Method for the Interruption Capability of SF6 Circuit Breakers

Numerical prediction methods both for the thermal interruption capability and the dielectric recovery capability of SF6 gas circuit breaker(GCB) are reviewed in the paper.The arc conductance 200 ns(G200) before current zero is a key parameter of the thermal interruption capability of the GCB.The magneto-hydro-dynamics(MHD) model is applied during the arcing process and the Mayr model is adopted near current zero to evaluate the G200.Then the arc time constant and the arc power loss coefficient could be obtained.To evaluate the dielectric recovery capability of GCB,the reduced electric field strength Ec has to be calculated everywhere in the interrupter after current zero.The reduced critical electric filed strength Ea has to be computed as well.The probability of the dielectric breakdown after current zero can be judged by the comparison of the Ea and Ec.It has to be indicated that the proposed numerical prediction methods are still need to be verified by further experimental efforts.