Study On Insulation Coordination And Arc Guiding Performance Of Ring Shape Parallel Gap Lightning Protection Devices For220kV Insulator Strings

The transmission line accidents caused by lightning strikes bring about a great dealof trouble to safety operation of power system, and have a significant impact to thenational economy and the daily life of the people. Minimize transmission line lightningaccident rate has been the pursuit of the power of science and technology workers. Theparallel gap connected to both ends of the insulator string is a guiding type lightningprotection device for transmission line. It can serve as a strong complement totraditional transmission line lightning protection methods. The parallel gap lightningprotection device(PGLPD) is economical、easy to install and has broad applicationprospects. Based on the PGLPD lightning protection performance study that has beenconducted by our laboratory, this article is mainly for insulation coordination、arc-guiding performance of the PGLPD. It is of great significance for theoreticalresearch and instructing engineering applications of the PGLPD.Aim at determining the suitable distance of parallel gap for transmission lineinsulator in our country. The standard negative lightning impulse and standard positiveswitching impulse flashover characteristics experiments on220kV compositeinsulator(FXBW4–220/100) with ring shape and rod shape PGLPD and220kVporcelain insulator(XP–70) with rod shape PGLPD separately were carried out in theNational Engineering Laboratory (Kunming) for UHV Engineering Technology wherelocate at the2100altitude area. The results show that the lightning impulse50%flashover voltage and switching impulse50%flashover voltage of composite insulatorwith ring shape PGLPD is higher than the porcelain insulator with rod shape PGLPD;the lightning impulse50%flashover voltage of porcelain insulator with rod shapePGLPD is higher than the composite insulator with rod shape PGLPD when the distancebetween the electrodes is same or closed.Based on the chain arc model, this paper founded the arc movement simulationmodel applied to ring shape PGLPD. The arc movement process with differentshort-circuit current level was simulated. The simulation results were validated by thearc-burning experiment results. Using this model, the influence factors of arc movementon the ring shape PGLPD were analyzed. The results show that the arc movementsimulation model on the ring shape PGLPD can accurately reflect the speed and trendsof arc movement. The ring shape PGLPD with an opening design can improve short-circuit current distribution on the electrode, which raising the arc-guidingperformance. The arc movement time on the ring shape PGLPD approximatelyexponentially decreases with short-circuit current increasing. The larger radius of ringshape PGLPD is, the faster the arc moves.Based on the impulse flashover characteristics experiment results of220kVinsulators with PGLPD, the insulation coordination situation between insulator andPGLPD were analyzed in this paper. Founding the transmission lines lightning model,this paper calculated the lightning trip rate and recommended the distance of PGLPD.The results show that the PGLPD can play the role of locating lightning flashover pointand protect insulator effectively when220kV composite insulator with1744mm ringshape PGLPD or1844mm rod shape PGLPD and220kV porcelain insulator with1722mm rod shape PGLPD. Meanwhile, the transmission line lightning trip rate willnot rise too much and the distance between the electrodes meet the requirement ofswitching impulse voltage withstanding value for220kV transmission line in china.