External Grounding Design to Reduce Effects of Lightning Damage in Distribution System

Abstract

This paper presents an external ground design in distribution system for improved lightning performance. Lightning protection is a set of features typically designed into grounding systems at locations subject to lightning damage. Basically, back flashover occurs when the amplitude of the lightning overvoltage experienced by insulator strings in response to direct strikes to a tower or to the shield wires at tower vicinities exceeds the insulation withstand of the line. The objective function is to reduce the effects of lightning overvoltage from back flashover is an attachment of external ground wire connected between the overhead ground wires and a ground rod. This paper analyzes the effects of lightning performance of 69 kV circuit in Metropolitan Electricity Authority (MEA)'s distribution system of Thailand. The proposed ATP-EMTP model for simulation and analysis of lightning in terms of pole top voltage, critical current and back flashover rate. The study results show that external grounding system design can reduce the effects of lightning and improve distribution system reliability.

Investigation and Optimization of Grounding Grid Based on Lightning Response by Using ATP‐EMTP and Genetic Algorithm

“…An equivalent circuit of the ground rod is shown in Figure 5. The resistance, inductance, and capacitance of the under transient phenomenon are calculated by [22]…”

Grounding Design Improvement to Reduce Back Flashover Rate of 69 kV Subtransmission Line in Power’s Distribution System

“…The critical current is defined as lightning stroke current when injected into the conductor causing flashover. When the critical current is known, BFOR expressed in flashovers per length of line per year can be calculated by [2][3][4] :…”