Optimization design of sensing coil of all-fiber optical current transformer

The all-fiber optical current transformer (A-FOCT) is based on the Faraday magnetic rotation effect for current measurement, and utilize closed-loop digital control which is to adapt the demand of future smart grid development. In this paper, the origin of linear birefringence in sensing coil was analyzed. The effect of linear birefringence on the measurement system error was investigated. The mathematical model was established, based on which, the simulation was performed to discuss the correlation among the sensing coil sizes, linear birefringence and fiber optical materials, and the size of sensing coil was optimized.