Surge Analysis on Wind Farm When Winter Lightning Strikes

Abstract

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, a phenomenon that has yet to be fully explained. In this paper, the authors present a case study using a wind farm model with multiple wind turbines connected to a power system. The aim is to clarify the influence of the grounding system on surge propagation from a wind turbine that has been struck to others which have not, during a winter lightning strike. Sensitivity analyses show that the surge propagated to nearby wind turbines can sometimes become large, depending on the conditions of the grounding system, and result in the burnout of surge arresters in turbines that have not been struck, especially during winter lightning strikes.

A Review of Current Issues in State-of-Art of Wind Farm Overvoltage Protection

“…The data needed for these models are sometimes difficult to obtain; the reason for this is that it often consists of several different components, each needed to be appropriately modeled for the lightning surge analysis [15,16,21,[36][37][38][39][40][41]. Moreover, wind farm component models are often frequency-dependent, non-linear or otherwise involve proprietary data belonging to the manufacturers.…”

“…This means that the surge arrester in fact "brings" the overvoltage from the WT grounding onto the phase conductors (at the WT which has been struck by lightning). Subsequently, this transient overvoltage propagates, by means of phase conductors, through the wind farm electrical system, and dissipates to ground through the surge arresters installed at other WTs (see Figure 4), [16,17,[19][20][21][22][23][24][25].…”

“…Consequently, all these aspects need to be accounted for when analyzing the overvoltage protection for a wind farm, particularly from the viewpoint of the lightning-associated surges, e.g., [16,18,19]. A prominent feature of wind farm overvoltage protection is a so-called back-flow surge-initiated by the direct lightning strike to the wind turbine-which needs to be accounted for and appropriately addressed [16,17,[19][20][21][22][23][24][25]. Additionally, the lack of experience with this rather new technology is another obstacle.…”

“…The main concern in wind farm overvoltage protection comes from the lightning overvoltages, which are the consequences of the direct lightning strikes on the associated wind turbines [17,21]. Transient behavior of the electrical micro-system of the wind turbine could have significant influence onto its overvoltage protection selection.…”

“…It could be argued that the energy capability required of MV surge arresters installed in wind farms often stems from the lightning surges, unlike with the surge arresters installed in typical MV distribution networks (where switching surges could dominate), e.g., [15,21,26]. Hence, a selection of energy capability, in regards to the lightning overvoltages, for the wind farm MO surge arresters is of particular importance.…”