Research on the Performance of the Lightning Protection System with Overlying Conductors on the Tip of the Wind Turbine Blades

The wind power system has always focus on the problem of lightning protection of wind turbine blades. Because of the increase of the capacity of wind turbines, the effective height of the wind turbines and the length of the blades also increase a lot, and the problem of the lightning protection failure of the existing blade lightning protection system (LPS) against direct lightning strikes has become prominent as well. There is still short of an optimization design of the LPS which can not only meet engineering requirements but receive all the downward lightning leaders. In this paper, a design scheme of overlying conductors on both of the leading edge and the tailing edge outside the tip of the blade was proposed to solute the delamination damage of the blades. This design of LPS could reduce the vicinal electric field of the down conductors, and reduce the probability of the streamer discharge incept from the down conductor as well as the discharge incept outside the laminate. The experimental study on the lightning protection performance was carried out under lightning and switching impulse voltage. The experimental results showed that the overlying conductors can effectively receive the downward leader to protect the blade from being penetrated in its laying range, but the protection efficiency would decline sharply when the downward leader developed outside the laying range. The covering length of the conductors should be 12% of the total length of the wind turbine blade, which can reduce the lightning damage by 90% or above.