Fault Line Selection Method Based On Zero Sequence Equivalent Conductance

Single-phase ground fault is usually accompanied by arc grounding,which generates a large number of harmonics,which is also produced by distribution network nonlinear load.Harmonics have direct impact on fault zero-sequence voltage,current distortion,the accuracy of decomposition of fault distortion signal by the existing signal analysis method as well as the selection method of the existing fault line.The paper is to calculate and analyze the single-phase ground fault signal with harmonics by the mathematical analysis suitable for the distortion signal,which can effectively improve the reliability of fault line selection and plays a significant role in ensuring the safe operation of the distribution network.The paper is to decompose the characteristics of distorted fault signals by the method of Fryze non-sinusoidal analysis under the action of distortion voltage and distortion current.Based on non-grounded neutral point operation and grounded neutral point operation by arc suppression coil,the paper is to analyze the relations of fault line and non-fault line equivalent conductance with harmonic voltage frequency,harmonic voltage distortion rate and harmonic current distortion rate of the relationship.When the system brings about single-phase ground fault,the fault line zero-sequence equivalent conductance is greater than the non-fault one.On this basis,the paper takes zero-sequence equivalent conductance as fault characteristic parameter to identify the ground line and design the algorithm of the line selection and adopts matlab software to write the relevant procedures.The calculation of zero-sequence equivalent conductance of a single-phase-to-ground fault through the Fryze current decomposition method can take harmonic factor into account.The method is not affected by the operation of the neutral point,especially for the identification of single-phase arc grounding fault.By changes in the neutral point grounding method,different line parameters and harmonic environment of the distribution network and stimulating analysis on the single-phase ground fault by the method of line selection,the results show that the line selection method can accurately select the fault line without being affected by the above changes,which turns out the reliability of selection method in the paper.