A Study of Fast Front Transients of an HVDC Mixed Transmission Line Exposed to Bipolar Lightning Strokes

Kyu-Hoon Park,Bang-wook Lee,Koo-Yong Shin,Ayesha Shakeel

doi:10.3390/en14102896

Kyu-Hoon Park, Bang-wook Lee + Show 2 more

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https://doi.org/10.3390/en14102896

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Abstract

Bipolar lightning strokes are associated with multiple polarity electrical discharge with no current intervals in between, making their behavior quite peculiar. This work presents a fast front analysis of a mixed high voltage direct current (HVDC) transmission link, evaluating the factors that influence the line transients due to shielding failures and backflashovers (BFOs), considering both overvoltage and repeated polarity reversal at the cable sending terminal. The research process includes a detailed modeling of a bipolar lightning stroke, frequency-dependent HVDC overhead, and underground transmission line sections. Noticeable findings include the occurrence of only a positive polarity insulator BFO for the adjacent and subsequent tower, despite the dual polarity of the lightning stroke with relatively small values for the lightning parameters. The influence of traveling waves on the insulator flashover performance of the line with varying parameters (such as the riser section length, the tower grounding impedance, and the location of the lightning stroke) is recorded and explained.

Highlights

There is increasing attention being paid to the significance of high voltage direct current (HVDC) interconnections in bulk power transmission, driven by their lower power losses, capacity, resilience to power outages, power flow controllability, and association with green energy sources [1]
overhead ground wire (OHGW) provides a shadow over the pole conductors for the sake of protection against lightning strokes in proximity of the transmission line
Insulation coordination strategy for underground cables is based upon the standard industry test waveshape (10 kA, 8/20 μs), and in adverse situations at an unprotected cable terminal, the surge doubles

Summary

Introduction

There is increasing attention being paid to the significance of high voltage direct current (HVDC) interconnections in bulk power transmission, driven by their lower power losses, capacity, resilience to power outages, power flow controllability, and association with green energy sources [1]. Overhead lines (OHLs) and cable systems were separately designed and established for transmission. Underground cables (UGCs) have lower environmental and visual effects compared to OHLs and can cover large distances in metropolitan areas [2]. The high economical and technical installation requirements associated with them cannot be overlooked. This led to the advent of more prevalent mixed HVDC links, containing both OHL and UGC sections. The effect of lightning overvoltages on OHLs in such links can traverse to the UGC section [3]

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