Stray Current Analysis Of DC Traction Power System

DC 1500V or DC 750V is used in most of the URT traction power supply system of our country.The currents from this system return back through running rail,then there may be a great deal of stray currents corroding structural reinforcing bars underground.Many buried metal pipes,such as gas pipes and water pipes would be destroyed when the stray currents leaked more seriously, that personal safety would be threated.So,it is necessary to study how to calculate stray current,rail potential and other measurements as accurately as possible,in order to predict and analysis the stray current and the polarization potential of structural reinforcing bars.Firstly,the calculation models based on multi-injected sources of stray currents and other measurements are obtained by differential element method and superposition principle.The models include: calculation models based on multi-injected sources of "Running Rail-Earth" (Two-Layer)earthing network structure, "Running Rail-Buried Metal-Earth" (Three-Layer)earthing network structure, "Running Rail-Current Drainage Net-Buried Metal-Earth"(Four-Layer)earthing network structure.Then three corresponding simulation models are developed with Matlab according to the calculation models. The simulation model on Four-Layer earthing network structure is divided into two conditions acorroding to whether input drainage cabinet,so as to analysis protective effect of current drainage net.Currents of injected sources and parameters of earth network are inputed into the simulation models of multi-locomotive supplied by multi-traction substation.Then,distribu-tion rules about stray currents and other measurements are obtained by large amount of simulations. The relevant parameters how to influence on stray currents and other measurements is analyzed through simulation results.At the same time,the models prove to be true.And then, the values of stray current,rail potential,structural reinforcing bars potential at new actual line and its initial operating stage are calculated.The same parameters are predicted under the condition of the insulation of running rails destroyed seriously.Finally,a software with visual interfaces has been developed for calculating rail potential and stray current with Matlab GUI.