Research On Influence Of Electrical Railway To Safe Operation Of Traction Substation Ground Wire

The rapid development of electrical railway has exerted some effects on the safe and stable operation of power system while meeting the needs of national economic and social development. Traditional harmonic and negative sequence current problems caused by electrical railway have been well studied, and effective solutions are proposed. However, it is not well explained that why electro erosion appears frequently on the ground wire near the first pole of traction substation power supply line in Yangquan and some other places. So, it is necessary to study the influence of electrical railway to safe operation of ground wire of traction substation power supply line.The specific ground wire connection with the traction substation grounding grid and electrical railway traction system characteristics are considered to result in current in ground wire near traction substation. This paper divides the problem into two sub-problems,"The cause of ground wire current" and "The distribution of ground wire current". For the former, the paper analyzes the distribution of backward current in traction system, derives the earth-return current flowing through traction substation grounding grid and obtains its GPR (Ground Potential Rise). Traction power supply system is modeled in PSCAD/EMTDC to study the influence of GPR of grounding grid to the ground wire current. For the latter, the current distribution along the overhead ground wire is derived based on a simplified overhead line model. The method is verified to be effective by obtaining and comparing current distributions through simulation result in PSCAD/EMTDC and program calculation result in MATLAB respectively. Finally, some factors affecting the ground wire current distribution are studied with the simulation model. Studies show that the ground wire current and the GPR of grounding grid have consistency and that ground wire current near the traction substation is larger relatively where electro erosion occurs easily comparatively.By reducing the GPR of traction substation grounding grid, the total ground wire current can be decreased in a view of source control. By changing the distribution proportion between ground wire and tower, more current can be leaded into earth in a view of dredging the current loop. The measures can be taken comprehensively to avoid the ground wire electro erosion efficiently.