Estimation of Energy Stress of Surge Arresters Considering the High-Frequency Behavior of Grounding Systems

This paper presents a probabilistic evaluation of energy absorption capability of transmission line surge arresters (SAs), based on Monte-Carlo method. In the presented approach, a wideband model of tower-footing grounding system is adopted taking to account both constant and frequency-dependent soil electrical parameters. Furthermore, the effect of multi-stroke lightning flashes on the energy stress experienced by SAs is taken into account. To this aim, simulation is performed for a typical 400-kV transmission line which is modeled in EMTP-RV. From the simulation results, it is found that the absorbed energy is significantly affected by the modeling type of grounding system, i.e., static or wideband model. This effect seems to be more pronounced for the soil characterized by frequency-dependence electrical parameters. The presented results show that wideband modeling of grounding system can affect the estimated lifetime and the energy absorption capability of SAs. Hence, the wideband model of grounding system is suggested to be taken into account for the proper selection and sizing of SAs.