Investigation on new mitigation method for lightning overvoltages in high‐voltage power substations

Mitigation of lightning overvoltage in gas insulated substations concerning ferromagnetic ring effect

“…The GIS busbar is modeled as a distributed parameter transmission line of surge impedance of 70 Ω and wave propagation speed of 290 m/μs. The circuit breakers, spacers and power transformers are modeled using lumped phase-to-ground capacitances with values of 50, 15 and 2000 pF, respectively [1]. In this section, the impact of GIS surge arresters and ferromagnetic ring on lightning overvoltages propagation, magnitude and steepness, is presented.…”

“…The towers are modeled using lossless transmission line with a surge impedance of 172 Ω (related to tower height of 53 m) and a wave propagation speed of 290 m/µs . Because the tower grounding model including the soil ionization effect results in decreasing lightning overvoltages because of back flashover, it is modeled using constant resistance value of 50 Ω for worst conditions .…”

“…This model and its parameter identifications are declared in Appendix B. For getting accurate model under fast transient overvoltages study, a capacitance of 25 pF per phase is added across the arrester terminals . In this study, the surge arrester burn out is investigated.…”

“…In high voltage power systems, to minimize equipment damage probability, insulation coordination needs to be studied . While various overvoltages types are encountered at power system components, lightning overvoltages are the dominant factor in determining equipment insulation requirements.…”

“…A capacitance of 25 pF per phase is added across the arrester terminals. This in order to achieve accurate model as well as accurate results under fast transient overvoltages study,[1,15].L 1 ¼ 0:03 Un (B:1) L o ¼ 0:01 Un (B:2)…”