6 results about "Modulus maxima" patented technology

The invention discloses a line fault detection method and device based on morphological wavelets, relates to the technical field of line detection, and solves the problem that in the prior art, when a single-phase grounding fault occurs in a small-current grounding system, the fault current is small, the characteristics are not obvious, and when line fault detection is carried out by using time domain, frequency domain and time frequency analysis methods, the fault current is not obvious. And the technical problems of low fault line selection accuracy and poor reliability exist. The method comprises the following steps: acquiring zero-sequence current signals in a period before and after a line fault occurs; pre-processing the zero sequence current signal; decomposing the preprocessed zero sequence current signal by using a morphological Haar wavelet; calculating modulus maxima of the plurality of lines according to the decomposition result; correcting the modulus maxima of the plurality of lines based on the line length; screening fault lines according to the corrected modulus maxima; the accuracy and reliability of single-phase earth fault line selection can be improved.

The application discloses a frequency band range selection method for fast traveling wave protection and a related device, and the method comprises the following steps: collecting positive electrode voltage data and negative electrode voltage data in a preset data window, and determining a fault initial line mode voltage traveling wave based on the positive electrode voltage data and the negative electrode voltage data; analyzing the fault initial line mode voltage traveling wave, and extracting a plurality of wavelet transform modulus maxima of different scales; comparing the plurality of wavelet transform modulus maxima of different scales with preset conditions, and determining a frequency band range of fast traveling wave protection based on a comparison result. The method realizes accurate selection of the frequency band range of fast traveling wave protection, and provides strong support for guaranteeing the reliability of fast traveling wave protection of a flexible direct current power transmission system.

This invention belongs to the field of positioning technology, specifically relating to a transient traveling wave positioning method for broken strand faults in overhead insulated conductors. The method includes: acquiring a single-end transient current signal of the line, obtaining a reconstructed signal through bandpass filtering, and performing an initial time-frequency domain transformation to obtain an initial time-frequency distribution; calculating the power spectrum and constructing a parallel time-varying parameter oscillator array to obtain multiple narrowband enhanced signals; performing a second time-frequency domain transformation on the enhanced signals to construct a fused time-frequency energy matrix; extracting the modulus maxima propagation path from the matrix; determining the arrival times of the initial traveling wave and the reverse polarity fault reflection wave based on the moment when the singularity characteristic index first enters the abrupt change threshold interval; and calculating the fault distance based on the calibrated traveling wave velocity and the single-end traveling wave ranging principle. This method effectively suppresses noise and enhances weak features, significantly improving the accuracy of wavefront identification and the reliability of single-end positioning.

This invention belongs to the field of positioning technology, specifically relating to a transient traveling wave positioning method for broken strand faults in overhead insulated conductors. The method includes: acquiring a single-end transient current signal of the line, obtaining a reconstructed signal through bandpass filtering, and performing an initial time-frequency domain transformation to obtain an initial time-frequency distribution; calculating the power spectrum and constructing a parallel time-varying parameter oscillator array to obtain multiple narrowband enhanced signals; performing a second time-frequency domain transformation on the enhanced signals to construct a fused time-frequency energy matrix; extracting the modulus maxima propagation path from the matrix; determining the arrival times of the initial traveling wave and the reverse polarity fault reflection wave based on the moment when the singularity characteristic index first enters the abrupt change threshold interval; and calculating the fault distance based on the calibrated traveling wave velocity and the single-end traveling wave ranging principle. This method effectively suppresses noise and enhances weak features, significantly improving the accuracy of wavefront identification and the reliability of single-end positioning.

This application provides a traveling wave ranging device, distribution terminal, fault monitoring system, and method for distribution networks, relating to the field of distribution network fault monitoring technology. The device includes: a current transformer for acquiring voltage / current traveling wave signals at corresponding detection points; a data processing unit, including: a phase-mode transformation module for performing phase-mode transformation on the voltage / current traveling wave signals to extract the line-mode components of each voltage / current traveling wave signal; a wavelet analysis module for decomposing the extracted line-mode components based on wavelet transform to obtain corresponding wavelet transform coefficients, performing modulus maxima search on all obtained wavelet transform coefficients, and generating a first detection signal representing the detection of the target modulus maxima if a target modulus maxima representing a line fault is determined; and a ranging calculation unit for determining the first fault location information based on the first detection signal. This application enables high-speed sampling and processing of traveling wave data, effectively improving the accuracy of distribution network fault location.

The invention provides an FPGA (Field Programmable Gate Array)-based improved continuous wavelet traveling wave fault wave head identification system and method. The system comprises a discrete wavelet module, a windowing module and a continuous wavelet module. In the discrete wavelet module, real-time fault pre-identification is carried out on the traveling wave signals based on a multilayer discrete wavelet algorithm; the windowing module performs windowing processing on the fault section signal; the continuous wavelet module obtains a wavelet coefficient through Fourier transform, frequency domain product and inverse Fourier transform, searches a modulus maximum line according to the multilayer wavelet coefficient, judges whether a local modulus maximum is caused by noise or a fault wave head, and achieves the precise positioning of the fault wave head. Compared with a traditional discrete wavelet traveling wave head identification method, the method is higher in frequency resolution. And more wavelet decomposition coefficients can be decomposed for the fault frequency band of the fault traveling wave, and the positioning precision is higher.