Upward Lightning at Wind Turbines: Risk Assessment From Larger-Scale Meteorology.

Area of Science:

• Atmospheric science
• Renewable energy engineering
• Electrical engineering

Background:

• Upward lightning (UL) is a major threat to wind turbines, causing significant damage due to large charge transfer.
• Less than 50% of UL is detected by lightning location systems (LLS), and UL is dominant in the cold season.
• Current risk assessments primarily focus on summer lightning detected by LLS, underestimating cold-season UL risks.

Purpose of the Study:

• To assess the risk of both LLS-detectable and LLS-undetectable upward lightning at wind turbines.
• To identify meteorological drivers influencing the occurrence of UL using direct measurements.
• To extend risk assessment models to a larger geographical area and validate their performance.

Main Methods:

• Direct UL measurements from instrumented towers were linked to meteorological data using random forests.
• Developed models were trained on tower data and then applied to a broader region (central and northern Germany).
• LLS-detectable lightning models were independently verified at wind turbine sites.

Main Results:

• Meteorological drivers for UL occurrence/absence were identified.
• Models for LLS-detectable UL were validated, showing reliable diagnosis at wind turbine sites.
• Risk maps based on cold season events demonstrated high probability areas coinciding with actual UL flashes.

Conclusions:

• The study provides a credible method for assessing UL risk, including previously undetected events.
• The findings indicate a higher overall risk and larger affected areas for wind turbines due to UL.
• This research improves the understanding and mitigation of lightning risks for renewable energy infrastructure.