Analysis of multiple lightning overvoltage on 110 kV transmission lines

• Multi-lightning is a common natural phenomenon but lack of research and attention; • Multiple return strikes can lead to more severe line overvoltage; • Arresters suppress multi-lightning overvoltage, thermal collapse aside. • The cable overvoltage caused by multi-lightning are lower than overhead line in hybrid line. As pointed out by the CIGRE TB 549 report issued by the International Power Grid Committee, more than 80% of cloud-to-ground lightning are multiple lightning strokes (MLS), posing a severe threat to overhead transmission lines. Most existing studies focus on single lightning strokes and ignore the impact of multiple lightning strokes. During an MLS, the first-time lightning stroke differs from the subsequent lightning strokes in the discharge process, affecting the external overvoltage of the transmission line. Hence, this paper establishes a high-precision simulation model of MLS hitting a 110 kV transmission line, considering the influential factors of lightning stroke parameters, shielding failure flashover, protection level, and back flashover position. Moreover, this model studies the overvoltage on pure overhead transmission lines and cable-overhead hybrid transmission lines caused by MLS. The results show that MLS produce higher line overvoltages than single-stroke lightning, and subsequent strokes are particularly detrimental to the transmission line, necessitating effective protection measures.