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Potential for the introduction of an alternating current traction power supply system with catenary supports without rail grounding

Objective: To study the problems and possible solutions in the introduction of an alternating current traction power supply system with catenary supports without rail grounding. Methods: To solve the set tasks, we used the statements and methods of the theory of power supply, experimental planning, mathematical and system analysis, and the theory of electrical measurements. In the experimental studies, the Trans-AURA Emergency Process Recorder and the Tektronix TDS 2014 Digital Oscilloscope were used, and the Aura2000 and MS Excel 2010 software products were used to process the experiment results. Results: The basic requirements for the AC traction power supply system grounding are presented. The flaws of the traditional grounding system of the catenary supports on the rail network are revealed. Two possible directions are described, which allow eliminating issues during the operation of the AC traction power supply system. The first direction requires the introduction of an additional stage into the traction network protection system, which makes it possible to identify short circuits through a high rail-to-earth resistance. The second suggests the need to revise the relay protection system itself, which includes changing the approach to grounding the catenary structures, the methodology for calculating the relay protection settings, a more detailed analysis of electrical safety conditions, etc. An equation has been formulated to determine support-groupto-earth resistance taking into account the group grounding cable and the existing requirements for ensuring the sensitivity of the main protection means, which allows ensuring reliable operation of feeders’ relay protection. The results of experimental tests of electrical safety conditions and electromagnetic influence are presented. The tasks are identified being the essential prerequisite to the widespread introduction of a system with supports without rail network grounding. Practical importance: The developed methodology for selecting the protection settings will make it possible to operate the AC catenary system without the supports’ rail grounding, as well as introduce the proposed additions to the instructions for grounding traction power supply devices at “Russian Railways”