Assessment of Energy Absorption by Surge Protective Devices in Low Voltage Lines Exposed to Indirect First and Subsequent Lightning Strokes

Abstract:
The statistical assessment of lightning-induced overvoltages in low-voltage overhead lines is challenging, as even distant lightning strikes can induce dangerous overvoltages in the line conductors, due to the low insulation level. A recursive stratified sampling Monte Carlo technique is used in this paper to improve the estimation accuracy of the lightning performance without unduly increasing the computational burden. The Monte Carlo generation of lightning events, conducted through a multivariate log-normal distribution, is refined by including a probability-weighted treatment for multiple return strokes per flash. As the representation of the channel base current using a trapezoidal waveform may result in an overestimation of the charge absorbed by low voltage surge protective devices (SPDs) installed at the line termination, simulations are carried out using the Cigré function. The lightning performance results align well with those obtained experimentally by Popolansky. The inferred statistical distribution of currents and energies absorbed by SPDs under various neutral grounding configurations provides valuable insights for an effective protection coordination.