输电线路光差动保护初探

全光纤电流互感器是通过Faraday磁光效应测量载流导体中电流,不存在磁饱和、测量范围广、线性度好。由于载流导体中电流磁场效应可以叠加,可将输电线路差动电流测量转换为利用光学器件在光路层面直接进行Faraday磁光效应偏转角的运算,不需要繁复的对时就可直接获得线路两端电流差值,在此基础上构成光差动保护。在PSCAD中搭建光差动保护模型,仿真结果表明光差动保护测量差流能够反映实际差流变化情况,采用固定门槛值的光差动保护对区内故障具有较高的灵敏度,在区外故障时具有一定的可靠性。

Research on Optical Differential Protection of Transmission Lines

An all-fiber optic current transformer measures current in the conductor according to Faraday magneto-optic effect, with a wide measuring range, excellent nonlinearity and no magnetic saturation. Since the magnetic field effect of the current can be superimposed, measurement of differential current from transmission line with sensing optical fiber can be replaced by direct calculation of Faraday magneto-optical effect deflection angle at the level of optical path with optical components, which means differential current of the transmission line can be acquired without complicated time synchronization to constitute differential protection. An optical differential protection model is built with PSCAD, the simulation results showing using the optical differential protection to measure differential current can reflect the variation of actual differential current while optical differential protection using fixed threshold value has a higher sensitivity to fault in the area and definite reliability for one outside. This work is supported by National Natural Science Foundation of China(No. 51477061).