The impact of multiple lightning strokes on the energy absorbed by MOV surge arresters in wind farms during direct lightning strikes

Abstract

This paper proposes a modelling and simulation process for assessing the energy absorption capability of metal oxide varistor (MOV) surge arresters used for lightning protection of wind turbines electrical systems situated in wind farms, when exposed to multiple lightning strokes. A section of an existing wind farm, suitable for lightning transient overvoltage analysis is implemented in the Electromagnetic transients programme-Alternative transients programme (EMTP-ATP) environment and modelled as a test system for analysing the energy absorbed by the medium voltage surge arresters when multiple lightning strokes are terminated on one of the blade of the wind turbines. Two well-established sets of multiple lightning current parameters are employed in the EMTP-ATP simulations; the natural downward negative multiple lightning strokes recommended by CIGRE TB 549 (2013) and the downward positive multiple lightning strokes recommended by IEC 61400-24-2010 for lightning protection level one (LPL1). The results show that the subsequent stroke causes the surge arresters to absorbed less than ten percent additional energy compared to that of the first stroke. This comparative analysis could be found beneficial when designing lightning overvoltage protection system and for selecting the most cost effective and optimal energy absorption capabilities of the surge arresters for the intended wind farms.