Direct Lightning Performance of Distribution Lines With Shield Wire Considering LEMP Effect

Assessment of the Effects of the Electromagnetic Pulse on the Response of Overhead Distribution Lines to Direct Lightning Strikes

“…The analysis of the LEMP contribution on the overvoltages due to direct strikes is presented for two pole configurations, shown in Fig. 1, having identical geometry of the phase wires, but one equipped with a shield-wire, i.e., the same configuration discussed in [12], and the other one with no shield-wire installed. The case study refers to a 1-km long distribution line with a span length of 40 m. Fig.…”

“…The strike is considered as a lightning channel very close to the line (10 m far from the line in the calculations presented in this paper). As discussed in [12], this simplifying assumption allows a good compromise between numerical stability, and accuracy of the results, assessed with respect to the ones provided by the FDTD model.…”

“…The detailed description of the FDTD model, including the domain discretization and the boundaries setup, can be found in [12]. The FDTD model is implemented and solved by using the 3D surge simulation code developed by CRIEPI called Virtual Surge Test Lab (VSTL).…”

“…The results of the recent analysis presented in [12] suggest that the LEMP effect may have an important effect on the lightning performance of distribution lines, especially in presence of periodically grounded wires. The aim of this paper is to extend the results of [12] and to compute the LEMP contribution also in case of a direct strike to the phase conductors of a line not equipped with a shield-wire. The analysis is initially performed by means of time domain comparisons to analyze the polarity and the magnitude of the two contributions (LEMP and current injection) to the total overvoltage.…”

“…This paper presents the calculation results of the response of a power distribution overhead line to a direct lightning strike, obtained by means of the following methods: -FDTD which intrinsically considers both the effects of the current injection and the LEMP-coupling with the line conductors, -EMTP which simulates the line response assuming the direct strike can be modelled by means of an equivalent current source, thus, neglecting the LEMP effect, -LIOV-EMTP in which the LEMP effect is also taken into account by using the LIOV-EMTP code [26], [27]. Since the use of 3D models requires a significant computational effort that makes them unsuitable for the statistical assessment of the flashover rate for realistic configurations, as in [12], the lightning performance is finally evaluated by means of the latter two aforementioned methods.…”