Analysis of the influence of secondary double fault of neutral point non-effective grounding distribution line on protection

The construction of a secure and reliable distribution network is a critical component of smart grid development. Overhead distribution lines, constantly exposed to atmospheric conditions, are susceptible to faults caused by lightning, strong winds, snow, and other external weather events. In recent years, the increasing frequency of extreme weather has resulted in more complex characteristics, such as the tics of the distribution-line faults. Under adverse weather conditions, transient single-phase grounding in distribution lines can lead to double-phase faults in adjacent lines and simultaneous lightning strikes on multiple lines can cause short-circuit faults. Current fault detection and relay protection technologies for distribution lines primarily address simple faults, and their ability to handle secondary double faults or multiple fault events requires a thorough investigation. This paper focuses on secondary double faults in overhead distribution lines within non-effectively grounded distribution networks. A simulation model of the overhead distribution network was established to investigate the occurrence of double-phase short-circuit faults triggered by single-phase grounding along adjacent lines. Characteristic measurements of complex faults were obtained and theoretically analyzed for accuracy. Based on these findings, the adaptability of existing overcurrent protection for distribution lines was analyzed.