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

Abstract

This paper presents the grounding design improvement to reduce back flashover rate from the lightning of distribution system. The Purpose to reduce effects of lightning overvoltage from back flashover. And study analysis of the condition effects of lightning performance of 69 kV on Metropolitan Electricity Authority (MEA)’s distribution system of Thailand. The technique objective function is an attachment the external ground wire connected between the overhead ground wires and a ground rod for reduce back flashover. Back flashover is one of the major causes of sustained interruption data. Occurs when the amplitude of lightning overvoltage is more than the limit of insulator strings specification. Then generated flashover on insulator skin and induces the voltage line. This paper simulation with Alternative Transient Program-Electromagnetic Transient Program (ATP-EMTP) and analysis of lightning performance in terms evaluated pole top voltage and back flashover rate (BFOR). Result after installing the external grounding design system can reduce the effects of lightning and can improve the reliability in distribution system. And the grounding systems designed is can use for guide line to the features typically at locations subject to lightning damage.