Research On Fault Line Selection Of Distribution Network Based On Improved EEMD

In the face of China’s low-carbon development trends and requirements in the next 40 years,as well as the background of "carbon peak" and "carbon neutral",the use of distributed new energy will inevitably increase,and a large number of distributed power sources will be connected to the grid.It is difficult to set the setting value of the short-circuit current,and it is difficult to select the line after the fault occurs.For the common low-current operating mode system distribution network in my country,the probability of single-phase grounding fault is the largest among various faults.In order to reduce the loss caused by the fault,it is necessary to find the faulty line as soon as possible to make the power system more stable.Therefore,it has certain practical significance to improve the accuracy of line selection by studying fault line selection methods.First of all,the characteristics of distributed power sources when they are integrated into the distribution network are studied.When a single-phase short-circuit fault occurs in the grid-connected state,the difference of the fault location can protect the electrical parameters such as the current of the distributed power source and the corresponding relay protection of the line.The device has different effects.When a single-phase fault occurs in a small current grounding system,the transient steady state of different grounding methods of the neutral point is analyzed,and then the interference source caused by the fault location is clarified.I use the SIMULINK simulation platform in MATLAB to build an equivalent model of the distribution network,use the EEMD（Ensemble Empirical Mode Decomposition）algorithm to decompose the zero sequence current signal,and improve the extracted high-frequency components based on the wavelet threshold denoising method.The Hilbert transform of the denoised high-frequency components is obtained and the instantaneous amplitude is extracted,and the faulty line is judged according to the principle of maximum energy ratio.In the case of changing a variety of variable parameters,multiple sets of simulation experiments are carried out respectively.Compared with the traditional EMD（Empirical Mode Decomposition）decomposition method for line selection,the improved EEMD single-phase ground fault line selection method can effectively remove noise components,strengthen transient components,and ultimately enhance the accuracy and reliability of line selection.