A transformer excitation inrush current identification method and device based on waveform change rate
A technology of excitation inrush current and rate of change, which is applied in the direction of measuring devices, circuit devices, emergency protection circuit devices, etc., can solve problems such as low recognition accuracy, failure, and large second harmonic energy, and achieve the effect of improving accuracy
Active Publication Date: 2019-11-19
GUANGDONG POWER GRID CO LTD +1
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Problems solved by technology
One of them is to use the Prony (Prony) algorithm to fit the energy formula of the fundamental wave and the second harmonic, and to distinguish the excitation inrush current from the fault current by comparing the ratio of the fundamental wave energy to the second harmonic energy, but when there is a DC When the magnetic bias and TA are saturated, the second harmonic energy is very large, and this method will fail, resulting in the problem of low identification accuracy
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[0073] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. The components of the embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations. Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.
[0074] It should be noted that like numerals and let...
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The embodiment of the invention provides a transformer excitation inrush current identification method and device based on waveform change rate. The method comprises the following steps: acquiring a to-be-identified differential current signal, sampling the differential current signal, and obtaining a sampling array corresponding to discrete sampling points; performing filtering processing on thesampling array, and obtaining a first array; performing normalization processing on the first array, and obtaining a corresponding second array; according to the second array, determining change rateof the differential current signal corresponding to the discrete sampling points; and according to quantity of the discrete sampling points of the change rate in a preset range, identifying the differential current signal. The embodiment of the invention is based on waveform characteristics of an excitation inrush current and a fault current, performs excitation inrush current identification according to the change rate of the differential current signal, realizes accurate identification on the excitation inrush current in differential protection and provides a reliable guarantee for a correction operation in the differential protection.
Description
technical field [0001] The invention relates to the technical field of transformer relay protection, in particular to a transformer excitation inrush current identification method and device based on waveform change rate. Background technique [0002] Differential protection is the main protection for internal faults in power transformers. The identification of excitation inrush current and internal fault current is a favorable guarantee for the correct operation of transformer differential protection. At present, the discontinuous angle principle and the second harmonic principle are often used in engineering to identify the inrush current. The discontinuous angle braking method is limited by TA saturation and hardware, and the recognition effect is not ideal in practical applications. Due to the existence of distributed capacitance and reactive power compensation devices in long-distance high-voltage transmission lines, the second harmonic content of the fault current in...
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IPC IPC(8): H02H7/045H02H1/00G01R19/00
CPCG01R19/0092H02H1/0007H02H7/045
Inventor 邹培源
Owner GUANGDONG POWER GRID CO LTD