Monte Carlo method for estimating backflashover rates on high voltage transmission lines

• Novel Monte Carlo method for backflashover analysis on transmission lines.
• Sophisticated transmission line EMTP model for backflashover analysis.
• Full statistical treatment of lightning current parameters.
• Statistical treatment of backflashover occurrence probability.
• Probability distribution function of lightning currents incident to transmission lines.
• Electrogeometric models of lightning incidence to transmission lines.

This paper presents a novel Monte-Carlo based model for the analysis of backflashover rate (BFOR) on high voltage transmission lines. The proposed model aims to take into the account following aspects of the BFOR phenomenon: transmission line (TL) route keraunic level(s), statistical depiction of lightning-current parameters (including statistical correlation), electrogeometric model of lightning attachment, frequency-dependence of TL parameters and electromagnetic coupling effects, tower geometry and surge impedance, tower grounding impulse impedance (with soil ionization), lightning-surge reflections from adjacent towers, non-linearity of the insulator strings flashover characteristic, distribution of lightning strokes along the TL span and power frequency voltage. In the analysis of the BFOR, special attention is given to the influences emanating from the insulator strings flashover characteristic and lightning statistics. The model could be applied to the transmission line as a whole or some of its portions, e.g. first several towers emanating from the substation or several towers crossing a mountain ridge.