Positioning method of single-phase earth fault sections in power distribution network based on extreme-point symmetric mode decomposition (ESMD)

Abstract

The invention relates to a positioning method of single-phase earth fault sections in a power distribution network based on extreme-point symmetric mode decomposition (ESMD). The positioning method comprises the steps that (1) whether a bus zero sequence voltage value exceeds the limit or not is determined, and if so, a step (2) is performed; and if not, the step (1) is repeated; (2)zero sequencecurrent signals in the 1 / 2 power frequency period after faults of all measuring points are collected; (3) the collected zero sequence current signals are subjected to ESMD decomposition, and a seriesof intrinsic mode functions IMF and a residual function R are obtained; (4) the intrinsic mode functions IMF and the residual function (R) obtained by the ESMD decomposition construct a fault transient energy function describing the oscillation intensity of transient zero sequence current waveforms; (5) based on the fault transient energy function, a fault section logic judgment function is constructed and subjected to normalizing processing; and (6) sections where faults are located are determined according to a power distribution network topological structure. According to the positioning method of the single-phase earth fault sections in the power distribution network based on the ESMD, the quite good adaptability to grounding faults under different grounding modes, different transitionresistances and different fault angles can be showed, and engineering is easy to realize.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to an ESMD-based method for locating a single-phase ground fault section of a power distribution network. Background technique [0002] When a single-phase ground fault occurs in the non-effectively grounded system, the line voltage continues to maintain symmetry, which can greatly improve the reliability of power supply. At present, the distribution network of major foreign developed countries is gradually shifting to the arc suppression coil as a whole. non-effective ground mode transition. However, in this kind of neutral point grounding system through the arc suppressing coil, because the arc suppressing coil compensates the capacitive current of the distribution network to a certain extent, the current distribution law of the entire distribution network has undergone a major change after the fault occurs. Locating and troubleshooting has brought ...

AI Technical Summary

Problems solved by technology

Judging from the actual use effect in recent years, the overall effect of the line selection and positioning method based on the steady-state quantity is not good, because it is easily affected by factors such as the neutral point grounding method, transition resistance and unstable arc, and has low sensitivity and is prone to misjudgment; A significant disadvantage of the signal injection method is that it requires a substantial increase in investment, and this method cannot fundamentally solve the problem of high-impedance ground faults; the transient method has been favored by academics in universities and manufacturers of electric wave recording devices in recent years, mainly because arc suppression The object of coil compensation is power frequency current, and it has no significant compensation effect on some high-frequency currents in the transient transition process. Based on this starting point, a series of technical solutions for fault line selection and location based on transient method are proposed, but based on different theories There are considerable differences in the effects and applicability of the transient line selection and positioning methods

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