500kV CVT内置低压电容C3测量过电压波形的试验研究

摘要

为验证基于内置低压电容C3电容式试验互感器(Capacitor Voltage Transformer,CVT)测量电力系统过电压波形的分压方式,即低压电容C3与高压电容C1和中压电容C2进行串联分压作为低压臂输出,基于无锡日新厂500kV CVT进行设备改造,串入了自制大容量无感电容单元(54μF)C3,分别进行了模拟工频过电压试验、操作冲击试验和雷电冲击试验.对采集获取的C3两端输出的数字电压波形信号进行了时、频域分析,以及分压比稳定性验证.试验和数据分析结果表明,串接自制大容量无感电容C3两端输出的电压波形光滑平稳,基本无过冲和振荡,分压比与设计值的相对偏差小于1％,即该分压方式适合用于超高压电网系统单次过电压波形的测量.%To validate a novel voltage-divider based on the capacitive voltage transformer (CVT) to measure over-voltage waveshape for power system, an element C3 in series connection with high-voltage capacitance C1 and media-voltage capacitance C2 as the low voltage part of sensor (LVPS) is used. A CVT of 500kV level provided by Nissin Electric Wuxi CO. , LTD was modified within a element C3 of 54μF in series connection. Lots of tests with ac simulation overvoltage, switch impulse and lightning impulse are done respectively to the modified CVT. Voltage waveshapes from the element C3 with digital sampling are analyzed in both time and frequency domains, and the stabilization of the voltage division ratio is also verified. The results of tests and data analysis show that the voltage waveshapes from the element C3 developed in series connection within CVT have a good characteristic with stable waveshape parameters, no overshoot and oscillation, and the relative deviation is lower than 1 % . It is feasible to be used in overvoltage waveshape measurements of power system with ultra-high voltage level.