Research on observation method of leader discharge thermal expansion based on quantitative schlieren technique

Abstract

Lightning is one of the main causes of UHV DC transmission lines trip-outs. To measure the leader discharge thermal expansion of leader could help us to have an in-depth understanding of the lightning protection. In this paper, a temperature measurement system based on calibration schlieren principle is developed in the first place. Combined with a high speed camera, the spatial resolution of this temperature measurement system is 100 μm/pixel. Secondly, the image process is discussed in this paper. Thirdly, the temperature distribution of an alcohol lamp is obtained by using this system. It shows a good agreement with the measurement results of precision thermocouple which validates the effectiveness of the developed temperature measurement system. Finally, this system is used to acquire the thermal expansion of leader discharge voltage in a 1m rod-plane gap, and the measurement results are discussed.