Analysis of Lightning Protection Performance between Externally Gapped Line Arrester (EGLA) And Non-Gapped Line Arrester (NGLA) On Distribution Networks in High Lightning Density Areas

Abstract

Lightning strikes are a primary factor contributing to temporary overvoltages in electrical distribution networks, especially in Medium Voltage Overhead Lines (MVOL). Such overvoltages can cause insulation breakdown, significantly impairing the reliability of the system. The purpose of this research is to evaluate the effectiveness of lightning protection by contrasting Non-Gapped Line Arresters (NGLA) with Externally Gapped Line Arresters (EGLA), while also identifying the most efficient setup. The approach involves conducting electromagnetic transient simulations using ATPDraw across four different scenarios: a system without protection, a setup with parallel NGLA, a scenario featuring series EGLA, and a combination approach. The factors assessed include residual voltage and Protective Margin (PM). The findings reveal that the unprotected configuration presents a high level of risk, with residual voltage surging to 145. 5 kV, resulting in immediate flashover. Utilizing NGLA brings the residual voltage down to 121. 7 kV; nonetheless, it achieves only a 19% PM, which is inadequate to avert premature backflashover. On the other hand, the EGLA setup exhibits better protective capabilities, clipping the surge waveform early at 105. 4 kV and yielding a secure PM of 30%. The study concludes that EGLA offers a markedly more efficient and dependable lightning protection option for 20 kV distribution systems when compared to NGLA.