The Influence of the Grounding Device Structure of a Substation on the Voltage of Conducted Interference of Lightning Currents

Abstract

A large number of microprocessor-based devices of relay protection, automation, and communication are used at electrical substations, the resistance of which to electromagnetic interferences is several orders of magnitude lower than that of the traditionally used electromechanical secondary machinery. Therefore, all technical specifications for the design of modern substations include requirements for electromagnetic compatibility, and, during the operation of substations, an examination of the electromagnetic environment is carried out. Methods of providing the electromagnetic compatibility when the substation lightning rod experiences lightning strokes are considered. The optimization criterion is the minimum of pulse overvoltage under conditions of lightning discharge. A new structure of a two-level grounding device providing minimization of the voltage of conducted interferences at the ports of microprocessor equipment when lightning strokes is proposed. This structure also provides latitude of choice in implementing layout solutions on the substation territory, in particular, when lightning rods are placed at distances from the equipment and cable channels that are less than the standard values. This makes it possible to reduce the area of a substation’s territory.