Research On Single-phase Grounding Fault Line Selection Of Small Current Grounding System Based On EEMD Algorithm

In today’s society,human beings rely more and more on electric energy.Among them,the distribution network is directly connected to users.The safe operation of the distribution network is an important guarantee for people’s safe production and healthy life.my country’s power distribution network mainly adopts small current grounding methods,including the neutral point grounded through the arc suppression coil and the neutral point ungrounded operation mode.Although the low-current grounding method has high reliability of power supply,after a single-phase grounding fault occurs,due to the small fault current,it is not easy to select the faulty line,delay the repair time,and even threaten the safe operation of the distribution network in severe cases.In order to ensure the reliability of power supply and ensure the safe operation of the power system,single-phase grounding faults in the distribution network should be discovered and eliminated in time.Therefore,the faulty line should be found quickly and accurately to ensure the safe operation of the distribution network and the continuous power supply for the people.Has extremely important significance.This article first introduces the current research status of domestic and foreign distribution network development,and summarizes the selection methods,advantages and disadvantages of single-phase ground faults in small current grounding systems.The steady-state and transient characteristics of the two grounding methods of the distribution network as well as the advantages and disadvantages,similarities and differences of the two grounding methods are introduced.Then the basic principles of empirical mode decomposition and fractal theory are introduced in detail,and a line selection method based on ensemble empirical mode decomposition and fractal dimension is proposed.Finally,the ungrounded power distribution network and the resonant grounded power distribution network model were built through MATLAB/SIMULINK,and a series of zero-sequence current data were obtained by using the two models to simulate.Take the zero sequence current of one cycle after the fault as the data to be analyzed.The ensemble empirical mode decomposition of the data to be analyzed is performed to extract the required results,and finally combined with the fractal box dimension,a single-phase grounding fault line selection method for the small current grounding system based on the combination of the EEMD algorithm and the fractal dimension is obtained.This method can extract high-frequency information reflecting the main components of the signal from the transient zero-sequence current with complex frequency components,avoid the influence of power frequency components and other low-frequency components,and provide effective transient components for line selection.At the same time,the line selection results are clear and intuitive,with high reliability.Simulation and actual test data verify that the fault line can be selected under different fault conditions,which proves the effectiveness of the method,and provides a new idea for single-phase grounding fault line selection in resonant grounding systems.