Analysis on lightning triggering possibility along transmission tethers of high altitude wind energy exploitation system

Recently a new concept of umbrella–ladder combination system to exploit the high altitude wind energy has been proposed. In this system the polyethylene polymer transmission tether plays an important role as the connection between the high altitude wind power absorber and the ground station. To make the concept practical, whether the tether would lead lightning to the ground station is one of the key issues. In this paper, the possibility of the polyethylene polymer transmission tether triggering lightning is studied. Firstly, the lightning environment characteristics are summarized, especially the possible potential distribution and electric field distribution. The charge structure of the thundercloud and the lightning activities which may affect the high altitude wind energy absorber are described. Secondly, the ways of the tether triggering lightning under thunderstorm in static electric field produced by charge accumulated in thundercloud and in impulsive electric field produced by lightning are analyzed. The lightning impulse characteristic of the tether and the influence factors on it are obtained through experiment and the result shows that the critical lightning impulsive breakdown electric field is about 300 kV/m. Therefore there is a great possibility that the tether triggering lightning. Finally the simple lightning protection for the system is discussed. © 2012 Elsevier B.V. All rights reserved.