Experimental study on lightning discharge attachment to the modern wind turbine blade with lightning protection system

摘要

Lightning strike is one of the most severe threats to the wind turbine blades and causes huge damage. Mostly wind turbines are struck by lightning when the blades are rotating. The effect of blade rotation on a lightning discharge attachment is unclear. Therefore, a rod electrode was used in a wind turbine lightning discharge test to investigate the difference in lightning triggering ability when blades are rotating and stationary. A standard switching waveform of 250/2500μs was applied to the rod electrode. Lightning discharge tests of a 1:30 scale wind turbine model with 3m air gaps were performed and the discharge process was observed. Three side receptors were used for Lightning protection system (LPS) of wind turbine blade (WTB). Distance between each receptor was 40cm and 1^streceptor had 5cm distance from tip of the WTB. Standard switching impulses (negative and positive) were applied to the WTB with different orientations and rotating speed. The experimental results demonstrated that when negative switching impulses were applied to the wind turbine blade, all the lightning discharges hit on the 1^streceptor; however, in the case of positive switching impulse, some discharges also hit on the other receptors, blade surface and nacelle of WTB. The attachment points remain same when the blade is stationary or rotating. The analysis revealed that polarity of switching impulse has significant influence on attachment point, and the rotation has little influence during the attachment process. The results can contribute to optimize the design of LPS of wind turbine blade.