Analysis and Experiment of Electromagnetic Induction on the Overhead Ground Wires of Single Circuit Transmission Line

Abstract

Overhead ground wires are essential parts of high voltage transmission lines. However, due to the phenomenon of electromagnetic induction, there is a huge energy loss on the overhead ground wires. In order to find a way to reduce the energy loss, or study the possibility of tapping off power from overhead ground wires, we studied in detail the law of electromagnetic induction phenomenon on overhead ground wires. This paper focused on the main single-circuit transmission lines with two overhead ground wires, especially the 500kV cup type tower and the 330kV cat-head type tower; the ground wires are grounded at every tower. Firstly, we built the equivalent circuit diagram of the transmission lines, and theoretically calculated the parameters of the components in the circuit diagram. Then, the electric field and magnetic field at the position of the overhead ground wire were numerically simulated in MATLAB, and an equal scale reduced model was built in COMSOL Multiphysics for finite element simulation, which more intuitively showed the distribution of the electromagnetic field around the transmission lines, the simulation results showed the induced voltage phase difference on two ground wires of cup type tower is more than 160° and the induced voltage phase difference on two ground wires of cat-head type tower is about 60°. The simulation also found the induced current will decrease slowly when the shielding angle increases from 0° to 15°. Finally, a transmission line simulation experimental device was built in the laboratory for verification and some conclusions were given in the end.