Behaviour of the Wind-Turbines Under Lightning Strikes Including Nonlinear Grounding System.

Abstract

Windfarms are every day increasing in number. So wind turbines are an easy aim for cloud-to-ground lightning for two main reasons: high isokeraunic level over windfarm locations and the height and sharp of the wind turbine structure and blades. Then the turbine should facility current flowing through its main parts: blades, rotor brushes and tower without dangerous overvoltages. Grounding should be design to derive current efficiently, but in many situations grounding is conditioned to particular location aspects such as: extension and soil resistivity. Both aspects are strongly related with grounding performance. This paper presents an analysis of a wind turbine overvoltages. It is modelled as a transmission line with different grounding models: a constant resistance, a nonlinear model based on soil ionisation, and a windfarm interconnected grounding model. Besides not only first lightning return strokes current are considered if not, subsequent return stroke current is included too.

Assessment of lightning current parameters suitable for wind turbine overvoltage protection analysis

“…Furthermore, it is a rather well affirmed fact that the front duration of the lightning current (among other factors) has a significant influence on the formation of the WT grounding transient potential rise. 5,12 Apart from that, lighting current front duration (in combination with amplitude) has important influence on the so-called back-surge propagation phenomenon, often associated with wind farms. 8 Generally speaking, direct lightning strikes with shorter front duration generate larger overvoltage on the associated equipment, and vice versa.…”

High-frequency modeling of Zafarana wind farm and reduction of backflow current-overvoltages

“…Although there are a lot of transients studies on the wind farms such as reported in , they did not take into consideration a complete high‐frequency modeling. In , the behavior of the wind turbine under lightning strikes using three models of the grounding system (constant resistance, nonlinear resistance, and frequency‐dependent model) has been studied. The constant resistance is not accurate under lightning surges.…”

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

“…The EMTP-type models for these components, appropriate for the lightning surge analysis, are not readily obtainable. One possible approach to modeling the WT tower-which heavily rests on the existing models of the HV transmission line towers-is presented in [39]. Here tower and blades are represented as simple constant-value and distributed-parameter transmission lines (i.e., the so-called Clark components in EMTP).…”

“…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.…”