Evaluation of the Transient Overvoltages of HVDC Transmission Lines Caused by Lightning Strikes

• Published in: Energies (Basel) 2022-02, Vol.15 (4), p.1452
• Main Authors: Zalhaf, Amr S., Zhao, Ensheng, Han, Yang, Yang, Ping, Almaliki, Abdulrazak H., Aly, Reda M. H.
• Format: Article
• Language: English
• Subjects: back-flashover; Case studies; DC towers; Electrical grounding; Flashover; HVDC transmission; Hydroelectric power; lightning overvoltages; Lightning strikes; Overvoltage; Shielding; shielding failure; Simulation; Systems stability; Transient performance; Transmission lines; Wind farms; Wire
• ISSN: 1996-1073; 1996-1073
• DOI: 10.3390/en15041452

High-voltage direct-current (HVDC) transmission systems are considered an outstanding solution due to high electrical losses emerging from long-distance transmission. However, HVDC transmission lines (TLs) are vulnerable to lightning strikes. In this work, the Yunnan-Guizhou 500 kV HVDC transmission system is used as a case study to evaluate the impact of lightning strikes on DC-TL overvoltages, as no research studies have been conducted to assess the lightning transient behavior of DC-TLs. A comprehensive investigation of the 500 kV DC-TL transient performance during lightning strikes is performed, taking into account different technical aspects that have not been studied in detail by previous researchers. Additionally, analysis of the back-flashover phenomenon has not been conducted well in previous work, and results on the effect of changing the lightning strike current peak and tower grounding resistance on shielding-failure flashover are quite limited. The distributed-parameter model is used to represent the DC-TL using the electromagnetic transients program (EMTP), considering real parameters of shielding wires and DC towers to study the lightning impact in the case of back-flashover and shielding-failure phenomena. Lightning strike is applied to the shielding wire, and the impact of increasing the peak value of lightning current is investigated on the back-flashover occurrence. Moreover, the influence of tower grounding resistance variation on the transient overvoltages across the tower body and back-flashover phenomenon is evaluated. From the simulation results, increasing the lightning current peak and grounding resistance results in higher overvoltages across the tower body, which increases the probability of back-flashover. Additionally, the shielding failure of the TL is assumed, and the variation impact of the lightning current peak and grounding resistance on shielding-failure flashover is investigated. The results show that the impact of the lightning current peak has a more significant impact than the grounding resistance in the case of shielding-failure flashover.