数字闭环光纤电流互感器动态特性仿真与测试

Simulation and test of dynamic performances of digital closed-loop fiber optic current transducer

基于Farady磁光感应原理及数字闭环信号处理技术的光纤电流互感器(FOCT),克服了电磁式电流互感器在暂态响应方面的弱点,满足现代电力系统对电流值实时精确测量的需求。针对数字闭环FOCT的动态特性,分析FOCT功能结构及信号传递过程,建立FOCT的数字闭环反馈模型,推导FOCT的传递函数,评估FOCT的幅频特性、相频特性、动态范围及频响特性;将故障瞬态电流的数学模型与FOCT的闭环反馈模型相结合,仿真FOCT对故障电流的暂态响应能力;构建电流实验平台,完成FOCT的动态性能测试。仿真与实验结果表明:FOCT的频带宽度大于7kHz,电流测量范围可达200kA,具有50次谐波的测量能力,并且FOCT的动态测量能力可根据具体应用需求调整。

Using Farady magneto-optical sensing principle and digital closed-loop signal processing technology,fiber optic current transducer （FOCT） overcomes the weakness of electromagnetic current transducer in transient current response and meets the demands of accurate current measurement of modern power system in real-time.Aiming at the dynamic characteristics of FOCT,the functional structure and signal transfer process of FOCT are analyzed based on its working principle;then,a closed-loop feedback model is built and its transfer function is deduced.Based on the feedback model and transfer function,the magnitude-frequency characteristic,phase-frequency characteristic,dynamic range and frequency response ability of FOCT are evaluated;moreover,the fault current transient responses are simulated using the closed-loop feedback model of FOCT combined with the mathematical model of transient fault current.An experimental platform was constructed and the dynamic performances of FOCT were tested in laboratory.Simulation and experiment results of FOCT show that its frequency bandwidth is larger than 7kHz,current measurement range is greater than 200 kA and up to 50th harmonic wave can be measured accurately;furthermore,the dynamic performances of FOCT can be adjusted according to practical application requirements.