采用LED光纤传感器的绝缘子串泄漏电流测量方法

测量绝缘子串的泄漏电流是目前监测输电线路绝缘子串表面污秽状态的主要手段之一,然而由于输电线路环境的复杂性,常常会伴生出大量的电磁干扰,会在泄漏电流的采集源头产生噪声从而导致采集失真。为提高传感器测量绝缘子泄漏电流的抗干扰能力和准确度,采用廉价稳定的光学器件—发光二极管(light emitting diode,LED)设计并制作了1套光纤传感器装置,利用光电转换和光信号的稳定性,以3片XP-160绝缘子串为试验对象,取盐密为0.05～0.2mg/cm2,在同一相对湿度(85%)下,采用逐渐加压法监测绝缘子串的泄漏电流。经试验验证,该光纤电流传感器可以实现选择性测量泄漏电流的正半周波或者负半周波,经过改进使用差分电路后可以实现测量全波泄漏电流,其零休时间<1ms,波形响应时间<0.1ms,测量电流的灵敏度达到40V/A,线性拟合度均>99.94%,频率响应在1～10kHz范围内,可以满足对泄漏电流测量的基本要求。

Measurement Method for Leakage Current of Insulator String Applying LED Optical Fiber Sensor

Measuring the leakage current of insulator strings is currently one of the principal means to monitor the contamination level of transmission lines insulator surface;however,due to the complex environment of transmission lines,a large amount of electromagnetic interference will produce much noise at the time of collecting leakage current.Therefore,in order to improve the anti-jamming and accuracy when sensors were used to measure insulator leakage current,an optical fiber sensor was employed to measure leakage current of the insulator strings,in which light emitting diode(LED) was used to detect the current signal as the photoelectric conversion and light signal stability.Taking three-piece XP-160 insulator strings as examples when ρESDD was 0.05～0.2 mg/cm2 and humidity was 85%,we increased the voltage gradually to obtain the leakage current.Results reveal that the optical fiber sensor can achieve selective measurement of leakage current,the positive half cycle or negative half cycle,and the full cycle current can be monitored after differential circuit is improved.Its zero-extinct period is less than 1 ms and response time is limited in 0.1 ms,and its sensitivity reaches 40 V/A.The pertinence coefficients of linear fitting are all higher than 99.94%,and its frequency response is 1～10 kHz,which can meet the basic requirements of the leakage current measurement.