Abstract
A significant majority of overhead transmission lines’ (OHLs) outages is due to backflashovers caused by direct lightning strikes: the realistic assessment of the lightning performance is thus an important task. The paper presents the analysis of the lightning performance of an existing 150 kV Italian OHL, namely, its backflashover rate (BFOR), carried out by means of an ATP-EMTP-based Monte Carlo procedure. Among other features, the procedure makes use of a simplified pi-circuit for line towers’ grounding system, allowing a very accurate reproduction of transient behaviours at a very low computational cost. Tower grounding design modifications, aimed at improving the OHL lightning performance, are also proposed and discussed.
Highlights
The lightning performance assessment of high voltage (HV) and extra high voltage (EHV)overhead lines (OHLs) is paramount, as the total outage rate of such lines is mostly influenced by the backflashover rate (BFOR) and the shielding failure flashover rate (SFFOR)
Overhead lines (OHLs) is paramount, as the total outage rate of such lines is mostly influenced by the backflashover rate (BFOR) and the shielding failure flashover rate (SFFOR)
Monte Carlo procedure for BFOR evaluation should employ an accurate model of tower grounding system, able to simulate the response of the system during fast transients related to lightning
Summary
The lightning performance assessment of high voltage (HV) and extra high voltage (EHV). Drastically reduced computation times, allowing the use of a detailed ATP-EMTP [25] model as the simulation engine in a Monte Carlo procedure for line BFOR evaluation [26,27,28]. The line is studied by means of the ATP-EMTP Monte Carlo procedure described in [26,27]; grounding system arrangements used by Terna are simulated by means of the pi-circuit model presented in [24], for different soil resistivities, ρg , ranging from 10 up to.
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