The Experiment And Study Of The Model On The Ventilation Of The SF₆ Leakage Diffusion In The GIS Cable Layer Of The Guangzhao Hydropower Station

The hydropower constructions fully use the renewable hydro-energy resources. It is an important Strategic significance for promoting China's energy structure adjustment. However, there is a possibility that the regular leakage of the SF₆ and the accident leakage of the SF₆ in the GIS cable layer when the hydropower station is in the operation, and the SF₆ can be broken up and dissociated by the high-power arc or the electric spark or the electric aureole, it can produce many kinds of products. These decomposition products often contain virulent poison, even trace, it can make up of a serious threat to the lives and safety of the staff entered the room. So the protective ventilation technology research of SF₆ is great realistic significance to protect the personnel health and to ensure the hydropower station is in the normal operation.This article takes the GIS cable level of the GuangZhao hydropower stations as an object to research and analyze the heavy-gas- pervasion which takes the SF₆ as a representative by the model test. This paper systematically studied the relation between the SF₆ concentration in the cable layer and the draft capacity, and the position of the extraction grille, and the SF₆ leakage amount and so on. Here are some results and conclusions are obtained. The correlative research may provide some scientific guidance and technical reference for the for the SF₆ ventilation design of hydropower stations.The similar principles in the hydromechanics that based on theoretical analyse is used by this model test, adopt the Funuode number Fr for the similar guidelines number. The kinds of parametric similar scale is deduced out basis on that take the geometric Scale between the model and the prototype as hypothesis condition, so as to lay the theoretical foundation for the model test.Through the model test, we can see that the height of the SF₆ leak point has an important influence to the SF₆ distribution in the cable layer. The SF₆ distribution in the cable layer displays a linearity distribution in the vertical direction. In the location beneath the leakage point, the measuring points higher the greater the SF₆ concentration; however, in the downstream of the Leak point, with the height of the measuring point increase the concentration of the SF₆ gas decrease. All the largest concentrations of the SF₆ in the cable layer are in the measuring points which underneath nearby the leak points in the kinds of experiments. Such factors must be given sufficient attention in such as the design of ventilation.Through the model experiment, we can see that the impact of the extraction grille position to the concentrations of the SF₆ in the cable layer is great.The more the extraction grille close to the leak point, the greater the extraction grille to the concentrations of the SF₆ in the cable layer, the draft capacity of the extraction grille which nearest the leak point decides the scope and size of the distribution. When all the draft capacity of the extraction grille is the same, the extraction grille that closest the leak point play the major role to the distribution of the SF₆ concentration in the cable layer.Through the model experiment, we can see the normal SF₆ leakage play a potty role to the SF₆ concentration in the cable layer, even the impact can be ignored.Through the model experiment, we can see that the more the draft capacity of the accident the smaller the SF₆ concentration in the cable layer, the faster the attenuation of the SF₆ Concentrations. But not that the larger the draft capacity the more ideal the energy efficiency ratio, when the draft capacity reach a certain level, if the draft capacity continue to be increased, the depressed rate of the SF₆ concentration would be not obvious.Therefore, from the ventilation effect to control the SF₆ pollution and the energy conservation points of view, this paper recommends the best draft capacity ought to be determined mainly based on the model tests.