Study On Magnetizing Inrush Current Based On Phase Space

Power transformer is an indispensable component in power system. Its working behavior determines the stability of the whole system. These years, the big machine set, high capacity and high voltage tendency become the development standard of power industry. This means higher demands to power system. Certainly, transformer voltage level is getting higher and higher and the manufacturing cost as well. Once fault occurs on transformer when operating, it may lead to great economic loss and a big sphere of influence. Meanwhile, related maintenance becomes more difficult. Therefore, to get a more reliable, safer and sensitive protection resolution is always the research focus at home and abroad.The primary factor of wrong operation is the imbalance current caused by inrush current. The emphasis of this paper lies in the research of inrush current. Thus, the principle of differential protection is analyzed at first. Then, we introduce some methods to identify inrush current and present some corresponding evaluation. At last, the focus of this paper is expanded in details. On the one hand, we compare the characteristics of the two models:common transformer and umec transformer provided by PSCAD/EMTDC. On the other hand, with the help of simulation, it’s feasible to acquire a lot of experimental data related to no-load closing under different working conditions.Based on the experimental data and some necessary analysis, a new characteristic of magnetizing inrush current is introduced in this paper. By reconstructing phase space with chaotic time-series, single current sampled signal from one-dimensional is mapped to hyper dimensional; Meanwhile, the phase locus indicates the difference between inrush current and inner fault current. Simulation exercise shows that it’s available to rebuild a similar phases pace under variable cases and the phase locus of inrush current is very different from the one of inner fault current. This explores a new idea to identify inrush current. In the last part of this dynamic model simulation,on which the software simulation results are validated,and further proved the practicability and reliability theory.