一种耦合法拉第旋光器的全光纤电流传感器

A Fiber-optic Current Sensor Coupled With a Faraday Rotator

电力系统暂态电流的实时感知对研究系统扰动、故障和控制保护具有重要意义。针对当前全光纤电流传感器难以同时兼顾宽频测量和宽温区适应性的难题,该文提出在传感光纤几何中点处耦合法拉第旋光器的直通式光路结构,并采用双线绕法绕制光纤环。采用琼斯矩阵建立该结构的理论模型,通过磁场和光场耦合分析该传感器结构降低环境敏感性的传感机理。通过试验测试传感器的频率特性和温度特性,结果表明,该传感器具有良好的频率特性:10Hz^10kHz频响试验的幅值误差不超过2.3%,相移小于2°;3k A标准8/20ms雷电冲击电流响应试验的误差小于2.1%,波形相似度为0.9971,表明有效频带可覆盖至标准雷电流;温度试验表明,该结构可显著降低传感器的温度敏感性,在-20℃~60℃范围内的误差小于4.3%(传统基本结构为29%)。该文所提出的全光纤电流传感器结构具有较好的频率响应特性和优异的温度适应性,满足电网暂稳态电流实时感知的要求。

The real-time perception of transient currents in power systems is of great significance for studying system disturbances, faults, and control protections. Given the difficulty in the current wide-fiber current sensors and the wide-temperature range adaptability, this paper proposed a straight-through optical path structure for fiber-optic current sensors by coupling a Faraday rotator at the geometrical midpoint of the double-wound sensing fiber. The theoretical model of the structure was established by Jones matrix, and the sensing mechanism of the sensor structure to reduce environmental sensitivity was analyzed by coupling magnetic fields and optical fields. Experimental results show that the sensors have good frequency characteristics from 10 Hz to 10 kHz. The amplitude error does not exceed 2.3%, and the phase shift is less than 2°. The error of the 3 kA standard 8/20ms lightning impulse current response test is less than 2.1%, and the waveform similarity is 0.9971, indicating that its effective frequency band can cover the standard lightning impulse current. Temperature tests have shown that the structure can significantly reduce the temperature sensitivity of the sensors, with a response error less than 4.3% in the range of -20℃~60℃(29% for the conventional basic structure). Therefore, the proposed fiber-optic current sensors have good frequency response characteristics and excellent temperature adaptability, and meets the real-time sensing requirements of transient currents in power systems.