| As a key equipment of power system, the reliability of Gas Insulated Switchgear is particularly important for the normal operation of the power grid. By detecting the type and concentration of the decomposition products of SF6 by Partial discharge in GIS,we can diagnose the equipment operation condition in advance and eliminate the latent fault of GIS. This is of great significance to the safe operation of the power grid. Aiming at this problem, this paper studied two methods for detecting the main decomposition products of SF6.In this paper, two technical methods were adopted. One method is Cryogenic adsorption combining with gas chromatography, another one is ion mobility spectroscopy technology. According to the different boiling point and melting point of SF6 and its decomposition products, target gas is condensed and separated by adsorbent. In this paper, we studyed the character of SOF2 and SO2F2 by three kinds of adsorbents: Porapak Q, F-03 and KDHF-03. And the quality of adsorbents we used were 2.2g, 2.5g, 2.5g in each experiment. Ion mobility of different gases is different. We studyed the migration characteristics of several test gases, such as O2, SO2, CF4, SOF2, SO2F2 and SF6. The experimental results show that:(1)When Concentrating SOF2, the best adsorption temperature of the three a dsorbents are all-50℃. The saturated adsorption capacity of SOF2 reached 4131.67μg, 2774.11μg and 3416.22μg, respectively. When desorption, Porapak Q can parse out SOF2 2933.65μg. It is suitable for the concentration and separation of SOF2 ga s.( 2) When Concentrating SO2F2, the best adsorption temperature of the three adsorbents are all-60℃. The saturated adsorption capacity of SO2F2 reached 1336.82μg, 1013.49μg and 1104.92μg, respectively. Porapak Q and KDHF-03 can parse out SO2F2 more than 800μg. Considering the factor of price, KDHF-03 is more suitable for the concentration and separation of SO2F2 gas.(3)At the adsorption stage, SF6, SOF2 and SO2F2 can be adsorbed a lot by the three kinds of adsorbents. But in the desorption stage, the desorption capacity of SOF2 and SO2F2 are much higher than that of SF6. In this case, low concentration of SOF2 and SO2F2 can effectively detected in the background of high concentration SF6.(4)In the experiment of ion mobility spectrometry, the number of electrons has a larger association with migration field strength and migration distance. And when migration distance reaches a certain value, it has little effect on the number of electrons. The migration time of electrons is mainly influenced by migration distance.(5)The study of ion transport characteristics of the sample gas shows that migration field strength(E) is the main factor affecting the ion migration velocity. The ion migration velocity increases with the increase of E. Ion mobility is related to E. Under the condition of low field strength, the ion mobility is greatly reduced with the increase of migration field strength. But when E > 142V/cm, the ion mobility tends to be stable.The study of the two methods provides a new way for the accurate detection of SF6 decomposition products. |
