Geomagnetic storm can cause Earth Surface Potentials(ESP)on the surface of the Earth.ESP pro-duces Geomagnetically Induced Current(GIC)in a loop made up by rail and the ground.The invasion of geo-magnetic storm into the 25Hz phase-sensitive track circuit will threaten the normal operation of track circuit. This paper analyzed the mechanism of the invasion of geomagnetic storm into the track circuit and the impact of GIC on the characteristics of choke transformer and track transformer.Further,the equivalent model of the re-ceiving end of 25 Hz phase-sensitive track circuit and choke transformer model were used,based on the actual parameters,to calculate the terminal voltage of track relay.As a result,when the nonlinear magnetizing in-ductance decreased from 2.3 Ωto 0.3 Ω,the terminal voltage of track relay winding decreased about 36.7%, causing the contact point of track relay to fall.Numerical calculation on GIC was conducted based on GIC flow path in the track circuit.Maxwell software was used to simulate the characteristics of theelectromagnetic sys-tem of choke transformer and track relay and to obtain their respective magnetic flux density distribution.The results showed that asymmetric GIC at 2.4 A can cause serious DC bias of choke transformer and decrease of terminal voltage of track relay,resulting in relay malfunction.This is a new problem that needs to be ad-dressed.%地磁暴产生后会在地表面引发感应电势ESP(Earth Surface Potentials),ESP在钢轨与大地的回路中产生GIC(Geomagnetically Induced Current).GIC侵入25 Hz相敏轨道电路中会威胁其安全运行.本文探究地磁暴侵入轨道电路的机理,分析了GIC对扼流变压器和轨道变压器特性造成的影响,采用25 Hz相敏轨道电路受电端等效模型和扼流变压器模型,根据实际参数对轨道继电器端电压进行计算,当非线性励磁电感从2.3Ω下降到0.3Ω时,轨道线圈端电压下降36.7%,就会造成触点落下.文中按照GIC在轨道电路中的流通路径进行GIC数值计算,利用Maxwell软件对扼流变压器和轨道继电器的电磁系统特性进行仿真,给出了两者的磁通密度分布图,结果表明:2.4 A的不对称GIC足以使扼流变压器严重直流偏磁,造成轨道继电器端电压下降并误动作,这是需要高度重视的新问题.
展开▼
