以选频平衡法测量局部放电的原理

PRINCIPLE OF SELECTIVE FREQUENCY BALANCE METHOD FOR PD MEASURING

传统的局部放电平衡测量法以电阻电容为输入电路，存在许多缺点，难以在高压和超高压领域推广使用。文中以电感电容为输入电路，全面分析了用选频平衡法测量局部放电的原理。模拟实验的结果表明，在选定的测量中心频率下，在调谐电容的调节范围内，存在着无数组平衡点。选频平衡法测量局部放电抑制干扰的关键是使用选频放大器。实际高压实验表明，在存在强烈干扰信号时，采用本测试法的测试电路在试样为２５５ｐＦ时，最小可测放电量可达０．０６ｐＣ。

Input circuit of traditional balance method for partial discharge (PD) measurement consists of two parallel circuits of resistance and capacitance.There are many disadvantages with this measuring circuit and it is difficult to spread its use in HV and UHV domain.The measurement principle of selective frequency balance method with input circuits of inductance and capacitance for PD detection is analyzed in detail in this paper.Simulated test shows that under the fixed center frequency of measurement,the innumerable balance points exist in adjustable range of tuned capacitors.The pivotal part of selective frequency balance method for PD is the use of narrow wide band filter and amplifier (NWBFA).Practical HV test shows that the minimum acceptable discharge magnitude is 0.06pC when the sample's capacitance in 255pF.Under the condition of very heavy interference signals.