Research On The Fault Line Selection Of Distribution Network Based On EMD And Fractal Theory

Most of our distribution network using a small current grounding,including the neutral point of the system and the arc suppression coil grounding system.Small current grounding system occurs single-phase ground fault probability is large,to more than 80% of distribution network failure.In order to improve the continuity of power supply,to ensure the safe and stable operation of power system,quickly and accurately detect the fault line,in the distribution network research is particularly important.In this paper,the fault steady state and transient characteristics of small current grounding system are analyzed,and the distribution of transient zero sequence current is introduced.A fault line selection based on EMD and fractal dimension method is proposed.Firstly,the zero sequence current data is collected,and the improved EMD algorithm is used to decompose the signal to obtain the IMF component of the characteristic frequency band.Secondly,the corresponding parameters such as the delay time and the embedded dimension are determined.After the parameter is determined,The problem is proposed and improved.Using the simulated annealing K-means algorithm to find the scale-free interval curve to get the line slope is the correlation dimension of the line.Finally,by comparing the size of the associated dimension,you can select the corresponding line of the faulty distribution network.In this paper,the simulation model of the small current grounding system of distribution network is established by MATLAB software.In order to test and verify the effectiveness of the method,a large number of numerical simulation and calculation of the fault are carried out.In the course of the experiment,the reliability of the fault line is based on the improved empirical mode decomposition and the fractal theory is improved by changing the position of the grounding point,the length of the line,the grounding resistance,the closing angle of the fault and so on.The results show that the improvement of the EMD algorithm and the improvement of the G-P algorithm can be effectively solved the problem of modal aliasing,end effect and reasonable selection of neighborhood radius interval.