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35results about "Form factor measurements" patented technology

Lightning stroke fault recognition method for EHV (extra-high voltage) DC transmission line based energy spectrum similarity

The invention relates to a lightning stroke fault recognition method for an EHV (extra-high voltage) DC transmission line based energy spectrum similarity, and belongs to the technical field of power system relay protection. The method comprises the steps: extracting the ratio of a positive time domain waveform to an area formed by the enclosing of the zero axis of the positive time domain waveform and the ratio of a positive time domain waveform of any fault type to the area formed by the enclosing of the zero axis of the positive time domain waveform during stable operation when the voltage of the EHV DC transmission line fluctuates, and recognizing the fault and lightning stroke interference according to the ratios; switching to fault classification recognition if the interference is a fault, carrying out the wavelet decomposition recognition of an additional component through wavelet, and judging whether the fault is a grounding fault or a lightning stroke fault; and switching to a shielding failure and back flashover fault recognition if the fault is the lightning stroke fault. The method achieves the time frequency analysis of the simulation data, achieves the extraction of data in a short time period, and integrates area ratios, energy spectrum similarity and modular maximum value. The method achieves the extraction of a set of criteria for thunder interference, grounding faults, back flashover faults and shielding failures, and can achieve the accurate, quick and effective recognition of various types of conditions.
Owner:KUNMING UNIV OF SCI & TECH

Lightning stroke fault determination method based on waveform difference degree and lightning stroke fault sample database

The invention relates to a lightning stroke fault determination method based on a waveform difference degree and a lightning stroke fault sample database. According to the method, when a fault occurs at a power transmission line, a travelling-wave fault range finding apparatus records a fault waveform; calculation is carried out by using a cubic b-spline wavelet to obtain an initial traveling wave arrival time of the fault; data 5ms after the initial traveling wave arrival time are selected to carry out normalization processing; the fault waveform after normalization processing is compared with all waveforms in the lightning stroke fault sample database and waveform difference degrees are calculated; and if a minimum value of difference degrees of the fault waveform and all waveforms in the lightning stroke fault sample database is less than a set threshold value, the fault type is determined to be a lightning stroke fault type; and otherwise, the fault type is determined to a non-lightning stroke fault type. According to the invention, compared with the existing lightning stroke fault identification method, the provided determination method has the following beneficial effects: confirmation of fault points by field line patrol workers is not required; the accuracy is high; and the method is simple and effective.
Owner:YUNNAN POWER GRID CO LTD ELECTRIC POWER RES INST +1

Method for detecting saturation of current transformer (CT) on the basis of third-order central moment

Provided is a method for detecting the saturation of a current transformer (CT) on the basis of a third-order central moment. The method comprises: sampling current at the secondary side of the CT; acquiring a current waveform from a position near the peak value of a waveform by using a data window in order to obtain a waveform symmetric about the peak value and with less sampling points; computing a dispersion coefficient by using the third-order central moment after the acquired waveform is subjected to waveform mirror image transformation; and outputting a detected result. In the method, a dispersion coefficient after a standard sinusoidal current waveform is subjected to mirror image transformation. By means of analysis and computation, the dispersion coefficient can be considered as a fixed value so as to be used as a comparison basis. The method mainly solves problems of low detection rate and low detection precision when the CT saturation occurs, may fast and accurately detect the generation of the CT saturation just by using sampled data in half cycle so as to improve relay protection reliability to a certain extent and have certain practical significance in the aspect of guaranteeing the accurate and reliable operation of the CT.
Owner:ELECTRIC POWER SCHEDULING CONTROL CENT OF GUIZHOU POWER GRID CO LTD +2

Identification method for excitation surge current of transformer based on kurtosis and skewness

The invention discloses an identification method for excitation surge current of a transformer based on kurtosis and skewness. The identification method comprises the following steps: initially setting a first setting value, a second setting value and a third setting value, performing uniform continuous sampling on differential current of the transformer by adopting an assigned sampling frequency to obtain a sampling value sequence; if a current effective value of the differential current is smaller than the first setting value, exiting the procedure, and otherwise, aiming at the current sampling value sequence, calculating the kurtosis and the skewness of the differential current of the latest power frequency cycle; if the kurtosis is greater than the second setting value and the skewness is greater than the third setting value, judging that the transformer is in an operation state of the excitation surge current, and locking differential protection of the transformer, otherwise, judging that the transformer is in other non-excitation surge current operation states; returning to continuously process the current effective value of the differential current. The identification method disclosed by the invention has the advantages of obvious criterion distinguishing degree, high correctness of identification result, low requirement on hardware realization, short judgment time, good real-time property and low requirement on hardware of an implementation device.
Owner:STATE GRID CORP OF CHINA +2

DC bias calibration device and method of zero intermediate frequency waveform generation system

The invention discloses a DC bias calibration apparatus and method of a zero-intermediate-frequency waveform generation system, and relates to the technical field of signal processing. The device comprises a measurement module, a feedback module, a processing module and a compensation module. The measurement module is used for measuring waveform signals output by a zero intermediate frequency waveform generation system; the feedback module is connected with the measurement module and used for feeding back a measurement result to a data processing unit of the zero intermediate frequency waveform generation system; the processing module is connected with the feedback module, is deployed in a data processing unit of the zero intermediate frequency waveform generation system and is used for processing the measurement data so as to obtain a DC bias compensation amount; and the compensation module is connected with the feedback module, is deployed in a data processing unit of the zero intermediate frequency waveform generation system, and is used for calibrating an output waveform signal according to the DC bias compensation amount. According to the invention, the measurement of the amplitude is converted into the measurement of the time delay, and then the calibration of the DC bias is completed.
Owner:INSPUR ARTIFICIAL INTELLIGENCE RES INST CO LTD SHANDONG CHINA

Transient current waveform and parameter measurement device of terahertz transit time device switch

The invention provides a switching transient current waveform and parameter measuring device of a terahertz transit time device, including a single-chip microcomputer, a display unit, a high-frequency pulse current source circuit, a blocking pulse voltage source circuit, a switching transient current waveform detection circuit and a switch Transient current signal processing circuit. When the single-chip microcomputer sends the first pulse signal to the high-frequency pulse current source circuit and the first detection instruction to the switch transient current waveform detection circuit, it receives the instantaneous When the transient current signal is turned on, or when the second pulse signal is issued to the blocking pulse voltage source circuit and the second detection instruction is issued to the switch transient current waveform detection circuit, the signal processing circuit receiving the switch transient current signal is to be tested. Transient current signals instantaneously blocked by terahertz transit-time devices. By implementing the invention, the transient current waveforms and parameters of the forward conducting and reverse blocking of the device are obtained, the measurement reliability is improved, and the operation difficulty is reduced.
Owner:WENZHOU UNIVERSITY

Arc fault detection method, device and equipment and storage medium

PendingCN113092955AConcise and easy to understand implementationTesting dielectric strengthForm factor measurementsTerm memoryNetwork model
The embodiment of the invention provides an arc fault detection method, device and equipment, and a storage medium. The method comprises the steps of obtaining a current waveform of a current signal of a current period and a current waveform of a current signal of a previous period; determining current waveform deviation characteristics of the current waveform of the current period current signal and the current waveform of the previous period current signal; and determining whether an arc fault occurs in the circuit according to the current waveform deviation characteristic and the first zeroing zone duration of the current waveform of the current period current signal. In the prior art, a large number of samples are needed to train an intelligent algorithm or a neural network model for arc fault detection. A large number of samples are not needed, and the early-stage investment of arc fault detection is reduced; sample limitation is eliminated, the method is suitable for most arc fault detection scenes, and the universality and accuracy of the detection method are improved; and an intelligent algorithm and a neural network model do not need to be set and operated in the detection equipment, so that the performance requirements of memory and the like of the detection equipment are reduced.
Owner:浙江华消科技有限公司

Identification method of transformer excitation inrush current based on kurtosis and skewness

The invention discloses an identification method for excitation surge current of a transformer based on kurtosis and skewness. The identification method comprises the following steps: initially setting a first setting value, a second setting value and a third setting value, performing uniform continuous sampling on differential current of the transformer by adopting an assigned sampling frequency to obtain a sampling value sequence; if a current effective value of the differential current is smaller than the first setting value, exiting the procedure, and otherwise, aiming at the current sampling value sequence, calculating the kurtosis and the skewness of the differential current of the latest power frequency cycle; if the kurtosis is greater than the second setting value and the skewness is greater than the third setting value, judging that the transformer is in an operation state of the excitation surge current, and locking differential protection of the transformer, otherwise, judging that the transformer is in other non-excitation surge current operation states; returning to continuously process the current effective value of the differential current. The identification method disclosed by the invention has the advantages of obvious criterion distinguishing degree, high correctness of identification result, low requirement on hardware realization, short judgment time, good real-time property and low requirement on hardware of an implementation device.
Owner:STATE GRID CORP OF CHINA +2

A Current Transformer Saturation Detection Method Based on Third-Order Central Moment

A current transformer saturation detection method based on the third-order central moment. Firstly, the secondary side current of the current transformer is sampled; secondly, the data window is used to intercept the current waveform again near the peak value of the waveform, and the sampling points symmetrical about the peak value are obtained. Waveform; after the waveform image transformation is performed on the intercepted waveform, the discrete coefficient is calculated with the third-order central moment; finally, the judgment result is output. In this process, it is necessary to calculate the discrete coefficient after mirroring of the standard sinusoidal current waveform, which can be regarded as a fixed value through analysis and calculation as a basis for comparison. The invention focuses on solving the problems of slow detection rate and low detection accuracy when the current transformer is saturated, and can quickly and accurately detect the occurrence of CT saturation by only using the sampling data of half a cycle, which improves the reliability of relay protection to a certain extent. Reliability has certain practical significance in ensuring its accurate and reliable action.
Owner:ELECTRIC POWER SCHEDULING CONTROL CENT OF GUIZHOU POWER GRID CO LTD +2

A Lightning Fault Identification Method for UHVDC Transmission Lines Based on Energy Spectrum Similarity

The invention relates to a lightning stroke fault recognition method for an EHV (extra-high voltage) DC transmission line based energy spectrum similarity, and belongs to the technical field of power system relay protection. The method comprises the steps: extracting the ratio of a positive time domain waveform to an area formed by the enclosing of the zero axis of the positive time domain waveform and the ratio of a positive time domain waveform of any fault type to the area formed by the enclosing of the zero axis of the positive time domain waveform during stable operation when the voltage of the EHV DC transmission line fluctuates, and recognizing the fault and lightning stroke interference according to the ratios; switching to fault classification recognition if the interference is a fault, carrying out the wavelet decomposition recognition of an additional component through wavelet, and judging whether the fault is a grounding fault or a lightning stroke fault; and switching to a shielding failure and back flashover fault recognition if the fault is the lightning stroke fault. The method achieves the time frequency analysis of the simulation data, achieves the extraction of data in a short time period, and integrates area ratios, energy spectrum similarity and modular maximum value. The method achieves the extraction of a set of criteria for thunder interference, grounding faults, back flashover faults and shielding failures, and can achieve the accurate, quick and effective recognition of various types of conditions.
Owner:KUNMING UNIV OF SCI & TECH
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