Damage mechanism of wind turbine blade under the impact of lightning induced arcs

Abstract

It is not clear for the damage mechanism of the blade structure under the effect of the lightning strike arc. In this paper, the damage characteristics of blades under the effect of lightning arc are obtained by the impulse large current experiment. Based on the actual blade structure, An MHD (magnetohydrodynamics) model is built suitable for multi-field coupling of heat-magnetic-airflow and we obtain the temporal and spatial variation of the temperature and pressure. The experimental results show that the blade tends to crack from the position of the trailing edge near the arc attachment point and the crack extends in the direction of the blade root and tip. The length of carbonization damage caused by high temperature of arc is much smaller than the crack length due to the airflow impact. When the down-conductor is placed on the main beam, carbonization damage distributes in the area between the left web and the trailing edge. When placed on the right web, it distributes between the right web and the trailing edge. In the finite element simulation, the temperature of the arc ignited point increases to the peak value and then decreases rapidly and then, it increases to the maximum and tend to stabilize. The high temperature inside the blade region diffuses from the boundary between the pressure surface and the right web to the trailing edge. The pressure of trailing edge increases to the maximum and then oscillates to decrease. The airflow inside the blade continuously oscillates between the right web and the trailing edge. It is recommended to improve the toughness of epoxy resin adhesive and set the down-conductor on the main beam.

Validation of a lightning protection system for a fusion-welded thermoplastic composite wind turbine blade tip

“…There was not a significant difference between the observations made here for the thermoplastic material and what is typically observed for a thermoset material (Zhang et al, 2019). In all cases, the flashovers did not go beyond the first layer of glass biax and were halted by the EAF, which indicates that this EAF worked effectively for the high-voltage leader attachment test cases.…”

“…The location where the blade is closest to the cloud (the ground plane in these tests) and has the smallest radii of curvature is the location of the highest electric field intensity, and hence the tip and leading edge are areas where ionization typically happens. Ionization is the separation of electrons from the atoms in the air, which releases photons and creates the light that is seen during a lightning event.There was not a significant difference between the observations made here for the thermoplastic material and what is typically observed for a thermoset material(Zhang et al, 2019). In all cases, the flashovers did not go beyond the first layer of glass biax and were halted by the EAF, which indicates that this EAF worked effectively…”