Analysis and Suppression of Back-Flow Lightning Surges in Onshore Wind Farms

The rapid expansion of wind power generation has brought problems involving lightning strikes to the fore. Many such incidents have damaged not only the wind turbine that was actually struck, but also other turbines that were not. The phenomenon of surge invasion to the distribution line is categorized as “back-flow surge”. It has been reported that this back-flow surge sometimes burns out surge arresters or breaks low-voltage circuits even far from the point of the lightning-struck. In this paper, an analysis of the back-flow lightning surge phenomenon is presented for two wind turbines connected to the grid using the PSCAD/EMTDC. This analysis is implemented for two different lightning surges. The analysis considers the nonlinearity of the grounding system of the wind farm and the point on voltage wave when the surge strikes the wind tower. This paper investigates the effect of a proposed addition grounding grid for each wind tower on the suppression of back-flow lightning surge in the onshore wind farm. The results demonstrate the effect of the grounding system nonlinearity and the effect of changing the point on voltage wave when the lightning surge strikes the wind tower on the back-flow surge phenomenon. The results show that the addition of a grounding grid for each wind tower highly decreases the bad effects of the back-flow lightning surge on the surge arresters.