A Ferromagnetic Resonance Fault Detection Method for Ungrounded Neutral System
A technology with ungrounded neutral point and ferromagnetic resonance, applied in the electrical field, can solve problems such as easy misjudgment, and achieve the effect of accurate results, reduced complexity and time consumption, and good convergence.
Active Publication Date: 2016-01-13
WUHAN UNIV
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[0003] The current ferromagnetic resonance detection methods mainly use wavelet analysis, zero-sequence signal threshold method and signal injection method, and it is easy to misjudge if there is an unrecognizable situation
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[0032] The present invention mainly comprises the following steps:
[0033] Step 1, record the three-phase voltage and zero-sequence voltage U of the bus during the fault 0 ;
[0034] Step 2, carry out atomic decomposition method analysis to A-phase voltage and zero-sequence voltage in the three-phase voltage recorded in step 1;
[0035] Step 2.1, use the atomic decomposition method to identify the parameters of the A-phase voltage signal, and obtain several best matching atoms of the A-phase voltage during the time period TA, where TA is from 0.21s before the fault to 1.79s after the fault; then Extract the characteristic parameters of each best matching atom, including the fitness value G, and the frequency component f of the best matching atom satisfying 0.1≤G≤1 Am , where m=1,2,3...n, n is the number of frequency components of the best matching atoms of the phase A voltage satisfying 0.1≤G≤1 between TA;
[0036] Step 2.2, for the zero-sequence voltage U after the fault ...
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The invention relates to a ferromagnetic resonance failure detection method of a neutral point ungrounded system. With the method, bus three-phase voltage and zero-sequence voltage signals are analyzed to detect ferromagnetic resonance failures of a system, a plurality of harmonic waves of adjacent frequency components are contained in the neutral point ungrounded system within 0.1s in the initial stage of ferromagnetic resonance, while only 50Hz of frequency component is contained in single-phase ground failure within 0.1s while the failure occurs, and the ferromagnetic resonance and the single-phase ground failure are distinguished at the initial stage of failure according to the essential difference of the ferromagnetic resonance failure and the single-phase ground failure, and then the resonance type of the ferromagnetic resonance is further detected. Atom decomposition method is taken as a ferromagnetic resonance signal analysis tool, a highly redundant atom library can capture natural characteristics of signals well, sparse decomposition of the signals is realized, and the representing result of the signals is concise and reliable.
Description
technical field [0001] The invention relates to the electrical field, in particular to a ferromagnetic resonance fault detection method for a neutral point ungrounded system. Background technique [0002] The working reliability of the power system is closely related to the magnitude of the overvoltage. In various accidents in the power system, insulation accidents caused by overvoltage are dominant, while ferroresonance overvoltage frequently occurs in the neutral point ungrounded system, which is serious It threatens the safe and stable operation of the distribution network. In some cases, ferroresonance is similar to the voltage signal characteristics of a single-phase instantaneous ground fault. Analyzing ferroresonance signals and detecting ferroresonance faults in power systems is conducive to realizing on-line detection of ferroresonance overvoltages. detect and prevent misjudgment of faults. At present, the analysis methods of ferromagnetic resonance signals are ma...
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IPC IPC(8): G01R31/08
Inventor 龚庆武张静李勋关钦月张英杰
Owner WUHAN UNIV