Grounding line selection method based on HHT signal analysis

Abstract

The invention relates to a grounding line selection method based on HHT signal analysis, which comprises the steps of 1) performing single-phase grounding fault analysis and fault line selection on aneural point non-effective grounding system by adopting HHT; 2) introducing an EEMD (Ensemble Empirical Mode Decomposition) method into signal sudden change detection, detecting the moment when a zero-sequence current signal of a signal feeder reaches a bus, and starting fault line selection; 3) extracting zero-sequence current transient signals, designing a low-pass filter with the window being apower frequency so as to filter out steady state signals in the zero-sequence current of each line and extract transient signals; 4) performing EEMD analysis on transient current i0k(t), that is, performing EEMD analysis on the zero-sequence transient current i0k(t), decomposing the zero-sequence current transient component i0k(t) containing various frequencies into a series of current IMFn components with different central frequencies, and searching a main frequency component concentration IMF; 5) performing time-frequency spectrum (Hilbert spectrum) analysis on the zero-sequence current signal of the feeder, that is, performing normalized Hilbert transform on the maximum IMFi obtained by EEMD analysis to obtain a time-frequency spectrum (Hilbert spectrum) of the zero-sequence current signal of the feeder.

Description

technical field [0001] The invention belongs to the field of power system distribution automation technology and power safety, and relates to a line selection method when a single-phase ground fault occurs in a distribution network neutral point via an arc-suppression coil grounding system, and specifically relates to a method based on HHT signal analysis Grounding method. Background technique [0002] my country's 6-66kV medium-voltage power grid generally adopts the non-effective neutral point grounding method, including the neutral point non-grounding system, the neutral point grounding system through the arc suppression coil, and the neutral point through the resistance grounding system, which is called the small current grounding system. , its advantage is that the ground current is small, the instantaneous ground does not trip, and the power supply feasibility is high. However, when a permanent ground fault occurs, in order to prevent the fault from expanding due to the...

AI Technical Summary

Problems solved by technology

[0003] The small current grounding system, especially the neutral point through the arc suppression coil grounding system, has a small fault signal and is difficult to distinguish, which brings great difficulties to relay protection and fault line selection

At present, the mainstream method of small current line selection is based on steady-state signal analysis, including the 5th harmonic method, active component method, and zero-sequence admittance, all of which are not accurate because the zero-sequence current and harmonic current are too small under fault steady-state conditions , in addition to the line selection method and the injection signal method based on the disturbance principle, the purpose of which is to increase the fault characteristic current, which increases the complexity and control difficulty of the grounding system

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