Abstract
In Hokuriku area, there are many lightning strokes through the year. Lightning strokes frequently cause power failures and instantaneous voltage drops on power systems, therefore various countermeasures against lightning faults on transmission lines have been taken. Recently, line surge arresters are installed as an effective countermeasure against multiple-phase faults that cause route interruption of transmission lines. The arresters are also one of the effective methods to reduce the frequency of instantaneous voltage drops. Hence it is thought that the rate of arrester installation will rise remarkably in the future. In order to take more effective countermeasures, it is indispensable to estimate lightning fault rate of transmission lines accurately in advance. In this paper, a method to estimate relative lightning fault rate of transmission lines depending on line design and lightning activity is proposed. Then lightning fault rate of 66/77kV and 275kV transmission lines with arresters is estimated by the proposed method and their accuracy is evaluated. Furthermore, the effectiveness of arresters for the improvement of reliability of transmission lines is demonstrated.
