Research On Phase Selection Of Single-Phase-to-Ground Fault In Distribution Network Based On Phase Space Reconstruction And Perceptual Hashing

At present,most of the research on fault phase selection focuses on transmission lines,and there are very few studies on phase selection in medium-voltage distribution networks.The distribution network in our country is mostly operated in a small current grounding mode,and single-phase grounding faults occur frequently.How to realize the phase identification of single-phase grounding faults is of great significance to the safe operation of the power grid.In this paper,a phase selection method for single-phase-to-ground faults is proposed by studying the phase-space correlation characteristics of three-phase currents in additional states.Based on the single-phase-to-ground fault model of the resonant grounding system,the theoretical and simulation analysis of the voltage characteristics of the sound phase and the faulty phase in the single-phase-to-ground fault of the system is carried out;and based on the fault additional network model,the phase space characteristics of the three-phase additional state current are analyzed.and simulation studies.The results show that the phase selection defect of the voltage amplitude method is that the voltage of the faulty phase is lower than that of the faulty phase under certain conditions.Its mapping is carried out in the phase space to study the fault characteristics of the three-phase current,and it is found that there are significant differences in the distribution,shape and size of the fault phase and the sound phase trajectories,and they are not affected by the fault conditions.characteristic basis.The similarity detection process of reconstructed phase diagrams based on perceptual hashing algorithm is studied,and a new fault phase selection method is proposed.In this method,after the fault line is determined,,the phase space reconstruction is used as a mathematical tool,and the three-phase additional state current of the fault branch is reconstructed to obtain the trajectory diagram of the original signal in the phase space,and then the discrete cosine transform is used to calculate Take the feature coefficient matrix of the reconstructed phase diagram,sort the matrix according to a certain coding rule to generate the hash fingerprint of the reconstructed phase diagram,obtain the Hamming distance of the hash fingerprint to complete the feature quantization of the reconstructed phase diagram,and according to This quantification results in the identification of faults.In order to effectively verify the reliability of the method proposed in this paper,a simulation model of 10kV distribution network was constructed by Matlab/Simulink,and an experimental tool for fault phase selection was designed based on Matlab/Appdesigner.The voltage amplitude method is compared,and the fault phase selection method is experimentally verified through the laboratory 380V simulation experiment platform.Both simulation and experiments verify the superior performance of the proposed method in single-phase-to-ground faults,especially in the case of high-resistance faults,indicating the effectiveness and adaptability of the proposed method.