Research On The Effects Of Geomagnetic Storms On Phase Detecting Track Circuit

Track circuit is an important part of railway signal system.The core part of signal system is composed of many microelectronic circuits,belong ing to the category of weak current and being vulnerable to external electromagnetic interference.When the geomagnetic storms occur,vio lent solar activit ies cause the dramatic changes of the geomagnetic field.The track circuit work abnormal phenomenon caused by geomagnetic storms has been reported,but it is not yet deeply.Therefore,researching the effects of geomagnetic storms on track circuit is of great significance,which is related to train operation safety and space weather cognition.Firstly,this paper explores the mechanism of the geomagnetic storm inva ding the track circuit in the form of GIC,analyzes the flow path of GIC on the track circuit,and estimate the levels of the GIC imbalance in the rail connecting with the research results on C hina's power grid geomagnetic induced current(GIC)data and the working principle of track circuit.Secondly,this paper monitors and collects the data during the medium-scale geomagnetic storms from September 2,2016 to September 4,2016 by the GIC monitoring device installed in C hang Hui inter-city railway Yanji high-speed rail traction station,and at the same time compa res and analyzes the record geomagnetic storm data of C hangchun C haoyang in the same time,which shows that the track circuit GIC flow is related to the occurrence of geomagnetic storms.Then,combining the actual technical parameters of choke transformer,the paper establishes choke transformer three-dimensional model based on Maxwell's software,simulates the electromagnetic characteristics,and gets a series of figures of choke transformer excitation current,core loss and magnetic chain under the influence of unbalanced GIC.The results show that the intrusion of GIC imbalance can cause serious choke transformer internal changes.After that,combined with the choke transformer equivalent circuit and orbital relay operating characteristics,the paper builds the intrusion of GIC imbalance to the phase detecting track circuit simulation model using Matlab software.The simulation results show that: 1.5A GIC imbalance is enough to cause choke transformer magnetic saturation,voltage waveform distortion on both ends of track relay and virtual value drop,which could make it less than release voltage,thus could lead to track relay drop and accidents because of signal error ind ication.Last,the paper introduces several methods of preventing track circuit to restrict the transmission of GIC imbalance and weaken the effects of geomagnetic storms on phase detecting track circuit.