A novel method to locate a fault of transmission lines by shielding failure

Lightning flashes on high voltage transmission lines are quite common and often lead to insulation breakdown which can cause outages in supply. The traditional way to locate the lightning fault on the line artificially is time-consuming. An accurate lightning location will result in faster maintenance and restoration of supply. In this paper, a novel distributed lightning fault location method for transmission line mainly for the shielding failure is proposed based on the non-contact lightning current monitoring system. First of all, according to the transient current wave polarity differences of three phases, the types of lightning are recognized, such as shielding failure, lightning striking the tower and striking the ground wire. Secondly, for the shielding failure, whether the flashover occurs or not is judged based on the timewindow energy ratio of the traveling wave. Thirdly, the lightning striking range in which interval of the line is determined by comparing the signals from all the detection points. Furthermore, the sides of lightning and flashover are distinguished. At last, combing the travelling wave method and wavelet packet transform (WPT), the arrival time of wave head is extracted. The specific locations of lightning and flashover are both calculated by using the signals from the two nearest detection points. By using EMTP-ATP software, a model of lightning striking at different points on a 110 kV transmission line with five detection points is established. The simulation results indicate that the proposed scheme is very effective in locating the lightning on the transmission line with reasonable accuracy, which has important application value.