Research on the aging degree of transformers and the change of gas content in transformer oil based on GC

As is known to all, it is the insulation system of transformer that guarantees transformer having a basic condition in which it can work and run normally. However, there are too many insulation materials of transformer. So, checking every insulation material is not practical to use. Currently transformer the most widely used in power system is oil-immersed transformer and GC has been proven to be a sensitive and effective way to test whether the transformer has fault or not. This article is based on GC to judge the aging degree of the same type transformers and the trends of gas in transformer oil by means of TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution) and the grey forecasting method. Firstly, comparing the aging degree of transformers by means of the TOPSIS. Although the TOPSIS cannot give the level of aging degree specifically, it can queue the transformers by the severity of aging. The result can not only provide the reference of replacing transformers, but also can give theoretical weapon to arrange the schedule of maintenance. Then, the grey forecasting method is used to predict the time transformers break down or need overhaul. In this paper, after given some data of the composition and content of gas dissolved in oil from a transformer, the conclusion that the data can be predicted for a medium time in the case of using the grey forecasting method. Notwithstanding, the accuracy of prediction is influenced by frequency and quantity of the sample point. If there are enough data that record the change of the gas, the prediction of the future will be satisfied to see. The possibility of transformers having faults can so big if the content of gas is more than a certain value based on GC. In the same way, transformers has faults when the content of gas is predicted more than the certain value at some point in the future. The grey forecasting method undoubtedly offer a good reference for the ascendant and save considerable money for ma- ntenance. All this will provide theoretical basis for the safe working of transformers in the grid within a medium time.