The Equivalent Circuit of the External and Traction Power Supply System

The article addresses matters concerned with determining the parameters of 25 kV AC external and traction power supply systems for calculating the voltage and short-circuit currents on the traction busbars in checking the electrical equipment and selecting the relay protection. Various equivalent circuits of the external power supply system are considered, namely, those stipulated by the relevant regulatory documents and the newly proposed one, which takes into account the electrical connection of high-voltage lines supplying power to traction substations. It has been shown that in calculating various operation modes of the traction networks of an inter-substation zone, the loads of adjacent zones should be taken into account, and the substation impedance parameters should be calculated in accordance with the short-circuit impedance (capacity) data represented by the power system. An algorithm for calculating the traction network of an inter-substation zone is proposed for determining the traction busbar voltage level with taking into account the traction substation leading and lagging power supply arms. An example of calculating the power supply model parameters of an inter-substation zone is given, which shows that the calculation of voltage losses will give an erroneous result if the load of the adjacent substation zone is not taken into account.