Optimum Number of Grounded Shield Wires underneath Extra High Voltage Direct Current Transmission Lines

Abstract

This paper is aimed at reducing the electric fields underneath extra high voltage direct current transmission lines using grounded shield wires. Two extra high voltage direct current transmission lines are modeled and analyzed. One line is homopolar and the other is bipolar, both are operating at 400 kV. The electric field calculated at the ground surface for the two transmission lines with and without grounded shield wires. In addition, the right-of-way limits for those transmission lines according to the maximum allowable electric field strength are calculated. The charge simulation method is used for calculating electric fields underneath the lines with and without grounded shield wires. A soft computer technique namely genetic algorithm was used also to determine the best location and number of grounded shield wires. The genetic algorithm was applied to a 400kV monopolar dc transmission; the best location of grounded shield wires is at 15m height above ground level for an optimum number of five grounded shield wires at spacing of 6m between them.

Keywords: Charge Simulation Method, Electric Field Calculation, Electric Field Reduction, Shield Wires, Direct Current Transmission Lines, Health Effects, Right of Way.