Investigation of weather conditions leading to different types of lightning strikes measured in wind turbine blades

The growing demand for sustainable energy has triggered the
constant development of taller wind turbines with longer
blades. The exposure of larger wind turbines to lightning is
unquestionable, no matter if it is onshore or offshore
installations. Since lightning damages are still one of the
largest drivers of downtime and repair cost, understanding
lightning exposure, and the protection strategies for mitigating
damages, is key for lowering the Levelized Cost of Energy.
Lightning exposure is partly related to the overall lightning
activity of an area, but also to the orography and weather
conditions, specifically the absolute distance of the wind
turbines to the thunderclouds and the direction of approach of
thunderstorms. Under certain conditions tall structures can
trigger the inception of upward lightning from the structures.

This paper presents an analysis of four wind power sites and
the weather conditions during storms that affected the wind
turbines with direct lightning strikes to the blades. The
lightning measurements have been performed directly in the
wind turbine blades by an appropriate lightning measuring
system (Certified to Annex L of IEC 61400-24 for Local
active lightning detection systems).

This work unveils how different types of meteorological
conditions and terrain topography lead to different types of
lightning. A better understanding of how exposure relates to
the local weather in the installation area is a key factor to
improve the input for the blade design processes, to perform
root cause analysis of damages due to lightning and to
schedule operations onsite improving cost and performance.