Modelling and Analysis of Currents Flowing in High Voltage Power Substations During Ground Short - Circuits

This article presents a method for determining the distribution of ground short-circuits in high voltage substations, in particular determining the value of currents flowing into substations grounding. Knowledge of these currents is important to assess the risk of electric shock hazard within the substation area. The EMTP-ATP program was used in the research, in which the structure of the analyzed systems was created. The results of calculations made for a selected high voltage substation in various work configurations are presented.

I. Introduction

Single-phase short-circuits represent the vast majority of disturbances occurring in high voltage power grids. Due to the fact that these power grids operate with a directly grounded neutral point, the values of single-phase short-circuit currents reach a significant level. In the event that a single-phase ground fault occurs at the substation, short-circuit current can cause a significant electric shock hazard [1], [2]. The part of ground current flowing into the substation grounding determines the hazard magnitude. All the conductive elements of objects located in the substation, neutral points of transformers and autotransformers, return conductors and power cable armors, also ground wires of overhead power lines, are connected to the grounding system. Tower grounding and adjacent grounding systems are also connected to the grounding system of substations via overhead ground wires [3], [4]. During a short-circuit to the ground fault in the substation, such an extensive system of connections causes all the above mentioned components to become a short-circuit current path.