A circuit model of buried metallic pipelines for the evaluation of shielding effectiveness to nearby communication lines

A universal model is presented to evaluate the shielding effectiveness of underground metallic pipeline network near power lines to communication lines, which takes both inductive and resistive coupling between power lines and pipelines into account. The model is based on transmission line theory. Each pipeline is treated as an active two-port network and is equivalent to a PI-type circuit with lumped current sources. A simultaneous equation group, whose unknown quantities are nodal voltages of the pipeline network, is constructed to solve the current distribution. The shielding effectiveness of the underground metallic pipeline network to the communication lines can be obtained. The model is time-saving because the parameter of the PI-type model can be calculated analytically, while the size of memory required is very small. The model is of significance to the design and the rights-of-way selection of power lines and communication lines.