| In the modern power grid with long-distance and large-capacity interconnected power supply in China,the probability of lightning strike on the line is greatly improved.Although the lightning resistance level and insulation level of the equipment applied to the power grid have been improved in recent years.But,it is still difficult to reduce the accident caused by the superimposed position lightning strike.The multiple backlash of the superimposed lightning strike is the source of the reignition of the arc,and the time interval between the two backlashes is very short.The traditional "Blocking Type" and "Sparing Type" lightning protection methods are not ideal,but once the reignition of the Repeated strike caused stable power frequency arcing,which will most likely cause large-scale blackouts accident.Therefore,it is extremely urgent to develop a new type of lightning protection equipment for the problem of current superimposed lightning protection.This paper develops a new type of impact-induced continuous triggering detonation airflow arc-extinguishing lightning protection gap device for appeal problems.The upper and lower interactive reversing structure adopted by the device can not only protect the traditional lightning strikes in a decentralized manner,but also can deal with the superimposed lightning strikes to take"one-on-one" measure.At present,the device has actually been Applied to the network and has achieved good effect.The specific research work of this paper is as follows:1)Theoretical modeling:By analyzing the basic arc parameters,the basis for judging the arc extinction is obtained,and the competition process of medium strength recovery and gap voltage recovery is further analyzed.The key to confirming the arc extinction is that the arc medium recovery intensity is greater than the voltage recovery speed.Based on a series of theoretical foundations,a one-dimensional wall-stabilized arc-column channel model is established.The electromagnetic characteristics of the arc during a single lightning strike flashover are analyzed,and then a superimposed lightning flashover model is constructed.Based on the established theoretical model,the detonation wave intensity generated by the detonation airflow is analyzed qualitatively and quantitatively.At the same time,analysis of the development and extinction process of the arc when the detonation airflow lengthways blows on the arc plasma and the arc develops and extinguishes.In the end,the scientific nature of DALPGD was demonstrated.2)Simulation analysis:The COMSOL software was used to geometrically model and simulate the arc-extinguishing process of the detonation airflow under the condition of superimposed lightning strike,and set the monitoring point to auxiliary analysis result.the distribution of temperature,conductivity and airflow velocity in the cavity of the arc-extinguishing cylinder calculated by simulation when the detonation airflow is lengthways blown to the arc.With the monitoring point curve analysis,DALPGD has a good arc-extinguishing effect for superimposed lightning strikes.3)Experimental verification:With a single arc-extinguishing test,the single arc-extinguishing interval of DALPGD is 4.0ms.Through the continuous trigger test,it is obtained that the two-time change bullet time of DALPGD is 21ms,and this interval time is much smaller than the double-backlash time of the superimposed lightning strike,which further proves that DALPGD is feasible for superimposed lightning strikes.Finally the insulation cooperation test of the last 500kV voltage class with DALPGD combination also verified that DALPGD can effectively protect the insulator.4)Practical application:After a certain line of Guangxi and Xinjiang power supply companies superimposed the flood-prone area to test the DALPGD,the lightning trip rate was greatly reduced and the lightning protection effect was significant.Finally,The results of the research prove that the application of DALPGD to superimposed lightning strikes is scientific and feasible. |
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