旋转高双折射全光纤型电流互感器

Spun High Birefringence All-Fiber Current Transformers

为了降低传感光纤的线双折射对全光纤电流互感器测量准确度的影响,将旋转高双折射(SHB)光纤作为互感器的传感光纤。根据琼斯矩阵,建立了互感器数学模型。研究了平面镜和法拉第旋转镜对基于SHB光纤的反射干涉式互感器测量准确度的影响,分析了SHB光纤的旋转比与互感器抗温度扰动能力之间的关系,讨论了使用光纤1/4波片对基于SHB光纤的互感器进行误差补偿的方案。结果表明,在平面镜式互感器中,采用谐波相除法、闭环信号调制法可以消除SHB光纤的长度敏感性。当旋转比大于30时,在-40~60℃温度范围内,标度因数的变化小于0.2%。在相同条件下,法拉第旋转镜式互感器中SHB光纤所需的最小旋转比为3.4,可见法拉第旋转镜提高了互感器的温度稳定性,选择合适的1/4波片可以补偿由SHB光纤线双折射引起的互感器标度因数温度误差。

To reduce the influence of linear birefringence of sensing fiber on the measurement accuracy of all-fiber current transformers, a spun high birefringence （SHB） fiber can be used as the sensing fiber of transformer. A mathematical model of transformer is established based on Jones matrix. The influences of plane mirror and Faraday rotator mirror on the measurement accuracy of reflection interference type transformer are studied. The relationship between the rotation ratio of SHB fiber and the ability of resistance temperature disturbance of transformer is analyzed, and the error compensation scheme for the SHB-type transformer which uses the fiber 1/4 wave plate is discussed. Results show that, for the plane mirror type transformer, the harmonic division method and the closed- loop signal modulation can eliminate the length sensitivity of SHB fiber. When the rotation ratio is larger than 30, the scale factor variation is less than 0.2% in the temperature range of -40-60℃. For the Faraday rotator mirror type transformer, the minimum rotation ratio for SHB fiber is 3.4 under the same condition. It indicates that the Faraday rotator mirror improves the temperature stability of transformer, and the scale factor temperature error of transformer caused by linear birefringence can be compensated when we choose an appropriate fiber 1/4 wave plate.