Application of Cable Lines in Electrical Networks Supplying DC Traction Substations

Overhead power lines are traditionally used to connect railway traction substations to 110–220 kV power grids. This approach has a number of disadvantages that can be eliminated by using cables with cross-linked polyethylene insulation. The objective of the presented research was to develop digital models to determine the modes of railway power supply systems with traction substations supplied via cables. For its implementation, the methods of multiphase modeling of electric power systems and the Fazonord AC-DC software product were used. The modeling results showed that the use of cables in external DC power supply systems of railways allows obtaining the following positive results: significantly reduce the width of the protection zone; avoid damage from strong winds and the formation of ice and frost deposits; reduce the risk of injury to people and animals from the effects of step potentials when wires break. In addition, when using cable lines, the minimum three-minute voltages increase by 10 … 11 %; active power losses in transmission lines are reduced by 9…20 %; and asymmetry factors – by an order of magnitude. Replacing overhead lines with cable lines makes it possible to reduce harmonic distortions at 110 kV substation inputs by 7…13 %.