Constraints on the use of surge arresters for improving the backflashover rate of transmission lines

• Published in: Electric power systems research 2020-03, Vol.180, p.106064, Article 106064
• Main Authors: Visacro, Silverio, Silveira, Fernando H., Pereira, Barbara, Gomes, Rafael M.
• Format: Article
• Language: English
• Subjects: Backflashover; Circuits; Computer simulation; Electric power lines; Electromagnetics; Flashover; Grounding; High rise buildings; Impedance; Insulators; Lightning; Lightning performance of transmission lines; Overvoltage; Phases; Risk; Risk factors; Surge arresters; Tower-footing resistance; Towers; Transmission line surge arresters; Transmission lines
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2019.106064

•The effectiveness of using surge arresters to protect transmission lines.•Maximum tower-footing grounding impedance for effective use of surge arresters.•Flashover at towers adjacent to towers protected by surge arresters. The effectiveness of using transmission line surge arresters (TLSA) under different conditions for improving the lightning performance of lines is assessed by means of computational simulation. These conditions comprise using TLSA only in critical towers and/or using devices only in certain phases, leaving one or two-phases unprotected. In addition to assess the effect on stricken towers, the transfer of overvoltage to unprotected adjacent towers is also addressed, considering different values of tower-footing impedance. In the analyses, lightning overvoltages across insulator of typical single-circuit 138-kV and double-circuit 230-kV transmission lines were calculated by using the Hybrid Electromagnetic Model (HEM) and flashover occurrence was assessed by using the Disruptive Effect method (DE), in each simulated condition. The results indicate that the operation of TLSA protects the own insulator and diminishes the backflashover risk at unprotected insulators. However, this risk remains high, depending on tower-footing impedance. Also, the risk of flashover at the unprotected adjacent towers due to the operation of surge arresters at the stricken tower was found to be significant in the case of all phases of the stricken tower protected, notably when the tower-footing impedance of the protected tower is high and that of the adjacent tower is low.