Transient Simulation of Conductive Coupling of HV Transmission Line with Underground Pipelines

In order to investigate the influence of the lightning current that flows to the ground on the metallic pipeline buried below ground, this paper calculates the maximum transient voltage imposed on coating of the pipeline when significant levels of lightning current flow to the nearby earth by using the frequency-based model of grounding grids calculation and combining the forward fast Fourier transform (FFT) and inverse FFT operation. It also computes the safety distances with and without grounding line. The computation results reveal that grounding lines can reduce the maximum transient voltage imposed on the coating of the pipeline and the denser the grounding lines are, the lower the maximum voltage is. Moreover, the calculation results are compared with those of the world popular software CDEGS and therefore the method is proved to be right.