基于电场探头及电流传感器的MOA运行状态带电检测方法研究

Metal Oxide Arrester On-Line Detection Based on Electric Field Probe and Current Transformer

作为一种电力保护设备,金属氧化物避雷(MOA)运行状态的准确识别是确保电网安全高效运行的前提之一。针对传统MOA运行状态检测方法中存在的检测准确性低,无法进行带电检测等问题,笔者提出了一种基于各次谐波原理的MOA非接触式带电检测方法。该方法采用一种改进的差分式电场探头和钳式电流传感器(CT)实现对于MOA电压与电流的信号采集,在此基础上对两路信号进行快速傅里叶变换(FFT),得到阻性电流等参数以实现对于MOA的检测。本研究开发了样机,详细介绍了样机的结构,推导了其传递函数,并分别对正常运行状态的MOA、老化和受潮的MOA进行了测试试验。结果表明,该样机能够准确采集到MOA阻性全电流、阻性基波电流及阻性3次谐波电流等参数,正常运行状态时幅值大小分别为23μA、17μA、5μA,受潮、老化相关状态下,阻性基波电流分别达到35.3μA和30.2μA,阻性3次谐波电流分别达到6.2μA和15.1μA,针对3种状态样机检测结果与在线监测系统基本保持一致,电流相对误差可达0.5%,且与已有文献相吻合,说明所开发样机符合MOA带电检测要求,具有良好的工业应用价值。

As a kind of power protection equipments,the accurate detection of MOA's running status is the premise to ensure the safe and efficient operation of power grid.Addressing the problems of common MOA detection methods,such as low detection accuracy and inability to conduct on-line detection of installed MOA,a MOA non-contact on-line detection method based on the various harmonics method is proposed in this paper.An improved differential electric field probe and a split-core type current transformers(CT)were used to realize the signal acquisition of the voltage and the current.And then fast Fourier transform(FFT)is performed on two signals to obtain the resistive current to realize the detection of MOA state.Finally,the prototype for detecting MOA state was developed,whose structure was introduced in detailed and transfer function was deduced.And tests were conducted on MOA under normal operating conditions,aged MOA,and MOA exposed to moisture.The results show that the prototype can accurately acquire the resistive full current,resistive fundamental current and resistive third harmonic current of MOA in the normal state,whose amplitude is 23μA,17μA and 5μA.The resistive fundamental current reaches 35.3μA and 30.2μA,and resistive third harmonic current reaches 6.2μA and 15.1μA when MOA in damped and aging state.The results of the MOA in the three states are basically consistent with the online monitoring system,and the relative error of current is up to 0.5%,which is consistent with the existing literature,indicating that the developed prototype meets the requirements of MOA live detection and has good industrial application value.