基于FARADAY旋光镜的光学电流互感器分析与试验研究

Study on Analysis and Test of Optical Current Transformer Based on FARADAY Rotation Mirror

为解决全光纤电流互感器因采用相位调制器、性能要求高的电子元器件以及复杂的调制解调算法等导致其成本高的问题,提出了一种基于法拉第旋光镜(faraday rotation mirror,FRM)的光学电流互感器(optical current transformer,OCT)方案;分析了该OCT的电流传感原理以及信号获取方法,试验研究了其电流测量精度和温度性能、谐波准确度以及振动特性,试验结果表明其满足5P20的要求,在-40~+50℃范围内,光纤传感环对该OCT系统误差影响不超过0.75%;OCT光纤传感环在承受10g的加速度冲击过程中,系统无异常信号输出。研制的该OCT主要技术指标满足中高压交流输电系统中保护级电流互感器的精度要求,可用于架空线—电缆混合线缆故障区域判别电流测量、分接开关故障电流监测等。

For solving the problem of high cost of optical current transformer due to adoption of phase modulation,high-performance electronic components and complex modulation and demodulation algorithm,a kind of optical current transformer(OCT)proposal based on FARADAY Rotation Mirror(FRM),is proposed in this paper. The current sensing principle and signal acquisition method of the OCT are analyzed,the current measurement accuracy and temperature performance,the harmonic wave accuracy and vibration feature are studied by the test. The test results show that it meets the requirements of 5P20. Within the temperature of-40~+50 ℃,the influence of the optical sensing coil on the system error of this OCT is no more than 0.75%. In case of withstanding 10 g acceleration shock by the OCT optical sensing coil,the system does not have abnormal signal output. The main technical specifications of the developed OCT can meet the requirements of control and protection of medium and high voltage AC transmission system,and can be used to measure the current used for the overhead line-cable mixed fault zone discrimination and monitor the fault current of tap-changer,etc.