合成回路用高压电抗器过电压分析及电场仿真

Overvoltage Analysis and Electric Field Simulation of High Voltage Reactor in Synthetic Circuit

高压电抗器在合成回路中为开断电流后的断路器提供恢复电压,断路器动作导致电路参数的瞬时变化,使电路中的电流和电压波形在高压电抗器和电容元件之间产生振荡,由此产生的过电压将威胁合成回路的安全运行。笔者根据试验单位提供的合成回路及具体运行工况,利用PSCAD对其运行回路进行电路仿真,得到相应的电流和电压波形,并以此为边界条件,利用ANSYS对高压电抗器进行仿真得到空间电场强度,并提出合适的结构参数来改善电抗器局部电场分布。结果表明:电路仿真在考虑电抗器杂散电容后,电流和电压波形出现极大振荡,此时电抗器两端的电压峰值可作为仿真边界条件。由电场仿真结果可知,电场强度的分布与电抗器的结构布置和对地电位有关,并以对地电位最大的电抗器两端的电场强度最明显,且主要集中在均压环处。通过选择合适的均压环尺寸,可以有效地降低该处电场强度。

The high voltage reactor provided the recovery voltage after the circuit breaker cutting off the current in the synthetic circuit. With the instantaneous variations of circuit parameters, the oscillating voltage and current waveform between the high voltage reactor and capacitor element would threat the safe operation of synthetic circuit. In the paper, according to the synthetic circuit and running condition, the waveform could be simulated with PSCAD. The voltage peak was used to be the boundary condition to calculate the elecrric field of high voltage reactor. Then the suitable measure was put forward to improve the electric field distribution. The results showed that the oscillating voltage and current waveform appeared after considering the stray capacitance and the voltage peak of high voltage reactor could be used as the boundary condition. With the results of electric field simulation, the electric field distribution was related to the structural arrangement and voltage to ground. The maximum electric field intensity appeared on the surface of grading ring with the maximum voltage to ground. Through selecting the suitable size, the electric field intensity of grading ring would be decreased significantly,.