Modeling of telecommunication lines for lightning overvoltage studies

With the progress of the information-oriented society, telecommunication lines are often installed on concrete poles along with power distribution lines. When a lightning stroke hits a distribution pole, the lightning current flows also through the telecommunication line in addition to the concrete pole and the ground wire. And, it is easily estimated that the existence of the telecommunication line reduces the currents through the concrete pole and the ground wire, and thus, reduces the voltage across the insulators to support the phase wires. However, its quantitative study has not yet been carried out. Considering the above, we have measured the surge impedance matrix of an actual-scale test distribution line equipped with a telecommunication line. Using this result, a method to model the distribution line system with the telecommunication line for lightning overvoltage simulations is proposed in this paper. Simulation results obtained by the proposed modeling method are compared with field-test results, and good agreement is obtained. © 2011 The Institute of Electrical Engineers of Japan.