Voltage Distribution Analysis of High Coupled Split Reactor in 500 kV AC Fault Current Limiter

With the increase of short circuit current, measures should be taken to reduce the impact. Among various measures, a new technique to interrupt or limit current is proposed and applied to power grid based on high coupled split reactor (HCSR). As the key equipment in new technique, the insulation design of HCSR is a priority. Previous works mainly involve voltage across HCSR in different working states, and take the whole voltages as design requirements. It is rough and takes no account of voltage distribution inside HCSR, thus not suitable for insulation design of HCSR. In order to analyze the overvoltage problems and determine insulation demands for HCSR, this article establishes the equivalent circuit model in turn unit to calculate the voltage distribution inside HCSR, which is simplified and accurate enough for HCSR. A 500 kV AC fault current limiter is briefly introduced, and voltages between turns or arms in HCSR are obtained. The voltage between turns are evenly distributed and voltage between arms are very low under switching impulse. As for lightning impulse, maximum turn-to-turn voltages mainly appear in the end of encapsulations, and the voltage between arms in current sharing state is considerable. This article gives the calculation method and general rules of voltage distribution inside HCSR, and it has great significance for the insulation design of HCSR.