Transient induced voltages on aboveground pipelines parallel to overhead transmission lines

Abstract

Lightning strikes to conductors of overhead lines may cause high transient induced voltages at neighbouring pipelines. Thus, the computation of these voltages is important for the safe and reliable pipeline operation. This work investigates the effects of line parameters and soil modelling on the transient voltages induced at an aboveground pipeline due to lightning strikes to a phase conductor of a nearby overhead transmission line. Three different earth formulations are evaluated: the Carson, Wise, and the method of moments with surface operator combined with the extended transmission line approaches. Computations are performed using both frequency- and time-domain models, as well as constant and frequency-dependent soil electrical properties. CIGRE lightning current waveforms are employed in simulations derived on the basis of the statistical distributions of their parameters for negative first return-strokes. Transient induced voltage waveforms differ among the evaluated lightning currents, with higher peak values for shorter and steeper current wavefronts. Conservative results are obtained for the constant soil properties and Carson’s earth formulations, which neglect, respectively, the dispersion of soil electrical properties and displacement current.