Analytical Formulas for Induced Surges on a Long Overhead Line Caused by Lightning With an Arbitrary Channel Inclination

This paper presents analytical formulas for lightning-induced surges (voltage and current) on an infinite length of overhead line, which are generated by a nearby lightning stroke with arbitrary striking angle. The formulas are derived using the Rusck model, which is one of the electromagnetic coupling models based on a transmission-line approximation of a return stroke. The return-stroke current is approximated by piecewise linearly varying characteristics. The formulas are simple and convenient for lightning-induced effect analysis. The analytical formulas are validated by the comparison with a finite-difference method. The paper proposes approximate formulas of peak value and time to peak value of the lightning-induced voltages for a vertical lightning channel.