Fault Line Selection Based On CEEMD Energy Specific Resonance Earthing System

As neutral earthing via arc-suppression coil (resonant grounding) is widely used in small current grounding system. In view of arc-suppression coil compensation effect of this grounding method, a lot of fault line selection methods based on steady-state component are no longer applicable. So, based on transient component of fault line selection methods have been proposed by researchers, which are widely used, but actual conditions are great randomness. In order to deal with these uncertainty factors, based on a variety of integrated algorithm fusion line selection methods have been proposed, so as to make up for the deficiency of the single line selection methods and raise the concept of reliability. Although the study of the resonant grounding system of single-phase grounding fault line selection is numerous, but so far the fault line selection of field application effect is not ideal. After an in-depth study on fault line selection, this article put forward a new fault line selection method based on transient component.First of all, this article analyzed the transient characteristics of single phase fault in resonant grounding system, derived the transient capacitance current, transient inductance current and synthesis of transient fault current transient expression. Then, a distribution network simulation model was set up by MATLAB/SIMULINK to analyze the transient characteristics, summarized the rule of transient characteristics under the different fault situation, provided theoretical basis for the following study.Secondly, this article used complementary ensemble empirical mode decomposition (CEEMD) to extract intrinsic mode function (IMF) and remaining component of zero sequence current. CEEMD not only overcame the modal aliasing, but also could effectively neutralize the added white noise. So, it made the decomposition more completeness. On the basis of it, the frequency band energy which corresponded with IMF was calculated, while using correlation analysis to get the correlation coefficient between IMF and zero sequence current. Then, correlation coefficient was used as weight coefficients for giving it to the frequency band energy. Furthermore, the weighted frequency band energy was accumulated as the energy of each line. Eventually, the energy of each line have been normalized as energy proportion to form a line selection criterion.Then, according to the actual situation of distribution network in China, a distribution network simulation model with hybrid transmission lines was set up. The results showed that this method could select the fault line regardless of fault close initial angles, fault location, transition resistance and etc. To some extent, this method improved the precision of fault line selection.Finally, this article made the brief analysis of the distribution network in Binhai district, selected the new 110 kV smart substation (Guolin substation) and took the 10 kV I mother system as the simulation object, combined with the actual equipment parameter for model building, used the fault line selection method which was proposed in this article to simulate. The results showed that the proposed fault line selection could select the fault line under different fault conditions, had a certain value in engineering application.