Simulation Research On The Interference Of Geomagnetic Storm Upon Track Circuit

Malfunctions of railway track circuits happened frequently in some countries and regions when geomagnetic storms occured. The principle and physical process about geomagnetic storms affect the normal operations of track circuits need systematic study.This paper preliminary study it by using the reasearch method of geomagnetic storms in medium or low latitude areas and the laws of signal system accidents caused by geomagnetic storms which happened in foreign countrise. According to ground characteristics of railway signal systems, this paper analyzed the generation of unbalanced GIC in impedance transformers of receiving end and calculation method of GIC on straight rails. The study estimated geoelectric fied in some domestic region through the use of Lanzhou geomagnetic observatory surveillance datas on November 9 2004, the railway’s geographic trend, one-dimensional conductivity model in this region. GIC level has been estimated by using parameters of railway equipments and geoelectric field datas. Analyzations about impacts of unbalanced GIC on impedence transformers by application of MATLAB/simulink software showed that interference caused transformer magnetic saturation which led to distortion and reduce of waveforms on the secondary side. The study analyzed voltage on signal relay of 97 type 25Hz phase detecting track circuit to research the possibility of malfunction of 25Hz track circuit The result showed that voltage on the relay became smaller and voltage phase change which could lead to semaphore malfunction when magnetic storm happened. Track circuit equipment’s voltage and geoelectric field that caused relay failure were also consistent with foreign accident record. Simulation in the paper verifies the scientific nature of physical process and principle which reveals the nature of faults on railway signal systems in high latitude countries. The work in the paper also can provide some references about further study on geomagnetic storms’ interference upon modern railway systems.