考虑时变间隙电容的隔离开关VFTO过程仿真

Simulation of VFTO Process for Isolating Switch Based on Time-Varying Capacitor

在气体绝缘组合电器（gas insulated switchgear,GIS）隔离开关动作时,隔离开关触头间隙电容量会随着触头移动而发生很大变化。利用Ansys Maxwell计算了1100 k V隔离开关间隙电容,动触头对地电容以及静触头对地电容。基于Bergeron法,推导了时变电容的迭代公式,利用ATP-EMTP中TACS/MODEL,在ATP-EMTP中实现了时变间隙电容C（t）。通过两个例子,验证了时变电容模型的正确性。利用时变电容模型,研究了时变间隙电容模型下VFTO全过程特性。仿真结果表明：相较于电阻电感模型和定值间隙电容模型,考虑时变间隙电容的模型对VFTO的幅值以及击穿时刻均会有较大影响。由于时变间隙电容C（t）考虑了全过程下间隙电容实际变化,其结果更加可靠,在一定程度上提升了VFTO仿真精度。

Gap capacitance of isolating switch changes with contact distance in whole open/close operation. Based on finite element method, gap capacitance of 1100 k V isolating switch, ground capacitances of dynamic contact and static contact are calculated. In this paper, an iterative formula of time-varying capacitance is deduced based on Bergeron method, where the time-varying model of gap capacitance C（t） is realized using ATP-EMTP TACS/MODEL. Subsequently, its validity is verified with two simple examples and used to VFTO simulation. Whole VFTO process characteristics under time-varying gap capacitance model are studied. It indicates that, compared to resistive inductance model and constant gap capacitance model, time-dependent gap capacitance model has great influence on amplitude and breakdown time of VFTO. In time-variable capacitance model C（t）, gap-changing capacitance is considered in whole open/close process. It is more reliable and improves VFTO simulation accuracy.