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Ferromagnetic resonance fault detection method for isolated neutral system

A technology of ungrounded neutral point and ferromagnetic resonance. It is applied in the direction of measuring electricity, measuring devices, and measuring electrical variables. It can solve problems such as unsatisfactory simulation results, complicated program use and maintenance, and calculations, so as to improve endpoint effects, Get rid of the constraints of linearity and stationarity, and avoid the effect of mode overlap

Inactive Publication Date: 2014-12-24
STATE GRID CORP OF CHINA +3
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Problems solved by technology

However, the program actually does not specifically calculate the ferromagnetic resonance phenomenon, so the simulation effect is not ideal, and the use and maintenance of the program are very complicated

Method used

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  • Ferromagnetic resonance fault detection method for isolated neutral system
  • Ferromagnetic resonance fault detection method for isolated neutral system
  • Ferromagnetic resonance fault detection method for isolated neutral system

Examples

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Embodiment

[0041] Embodiment: A method for detecting a ferromagnetic resonance fault in a neutral point ungrounded system, comprising the following steps:

[0042] Step 1: The fault recorder records the three-phase voltage of the busbar and the zero-sequence voltage signal U 0 ; At least record the busbar three-phase voltage and zero-sequence voltage waveforms from t1 seconds before the fault to t2 seconds after the fault, where t1∈[0.1, 0.2], t2∈[2.0, 3.0];

[0043] Step 2, the bus three-phase voltage and system neutral point U recorded in step 1 0Perform fast Fourier transform (FFT) on the voltage to obtain the frequency components contained in the signal, construct a filter with a specified bandwidth, filter the signal, separate the frequency components, and preliminarily judge single-phase ground faults and ferromagnetic resonance faults; preliminary judgment The single-phase ground fault and ferromagnetic resonance fault are based on the fact that the single-phase ground fault of t...

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Abstract

The invention discloses a ferromagnetic resonance fault detection method for an isolated neutral system. Three-phase voltage and a zero-sequence voltage signal of a bus are analyzed to detect the ferromagnetic resonance fault of the system. According to the method, with Hilbert Huang transform (HHT) based on empirical mode decomposition (EMD) as the core, in combination with FFT, FFT analysis is firstly performed on the three-phase voltage and the zero-sequence voltage signal, then HHT analysis is performed, and finally the moment of ferromagnetic resonance and the amplitude value of ferromagnetic resonance over-voltage are obtained through a three-dimensional Hilbert spectrum, so that the ferromagnetic resonance type, the amplitude value and the inducing moment are accurately analyzed in a quantified mode. The HHT signal analysis method is adopted for completely getting rid of linearity and stability constraints, namely, frequency-domain analysis can be performed on the voltage signal, and meanwhile time-domain analysis can be performed; in the process of HHT analysis, an RBF-point symmetry continuation method is adopted, in combination with a mirror image continuation method, the end effect of HHT is improved, and mode superposition is avoided.

Description

technical field [0001] The invention belongs to the field of power system safety analysis and relates to a ferromagnetic resonance fault detection method for a neutral point ungrounded system. Background technique [0002] The neutral point ungrounded system contains many inductive and capacitive components (such as inductance of transformers, transformers, etc.; ground capacitance and phase-to-phase capacitance of transmission lines), which can form a series of oscillation circuits with different frequencies. In these loops, the voltage transformer (abbreviated as PT) is an iron-core inductance element. If there is some kind of large disturbance or operation, the nonlinear iron core of the PT may be saturated, thus forming a special relationship with the ground capacitance of the line and equipment. The single-phase or three-phase resonant circuit excites a continuous high-amplitude ferromagnetic resonance overvoltage. The abnormal overvoltage and overcurrent that appear d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/00
Inventor 何菲孙志陈国珍王倩蒋浩
Owner STATE GRID CORP OF CHINA
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