Technical-economic analysis of conventional and non-conventional techniques to improve the lightning performance of transmission lines: Extended counterpoise grounding wires and underbuilt wires

Abstract

• Lightning performance of 230- and 500 kV TL is assessed by computational simulations. • Technical-economic analysis of techniques to improve lightning performance is shown. • Installation of extended counterpoise wires and underbuilt wires is considered. • Decrease of 88%-to-94% in BFOR is obtained with the use of underbuilt wires. • Underbuilt wires is economically viable mainly for high resistivity soils. This work presents a technical-economic analysis of using extended counterpoise wires and underbuilt wires to improve the lightning performance of typical 230 kV and 500 kV transmission lines. The installation of underbuilt wires leaded to decreases up to 88% and 94% on the backflashover rate of the lines with high tower-footing grounding impulse impedance. Also, it is shown that the cost of installing one underbuilt wire combined with the extension of counterpoise wires converges to the cost related to the intervention only on grounding for increasing values of soil resistivity. A difference of only 3% between the costs of both techniques was indicated for the 230 kV TL installed over a soil with resistivity of 20,000 Ω.m. These aspects indicate the use of underbuilt wires as an economically viable solution for improving the lightning performance of transmission lines, mainly for high resistivity soils.