Excitation surge current detection method, excitation surge current brake method and excitation surge current detection device

A technology of excitation inrush current and detection method, which is applied to measurement devices, circuit devices, emergency protection circuit devices, etc., can solve the problems of decay time that may reach tens of seconds, intermittent excitation inrush current waveform, etc., to ensure reliable operation, avoid interference, Accurate effect
CN103675415AActive Publication Date: 2014-03-26SIEMENS AG
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
SIEMENS AG
Publication Date
2014-03-26

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Abstract

The invention discloses an excitation surge current detection method and device. The method comprises the following steps: obtaining differential current ix(n) of each alternating-current phase of a transformer; for the alternating-current phase, based on the differential current sampled in a cycle, calculating at least two factors (Ax(n), Bx(n)) used for waveform symmetry judgment; for each factor, obtaining a maximum value of three factors corresponding to three alternating-current phases as a maximum phase factor of the factors; based on the obtained maximum phase factor, calculating a corresponding waveform symmetry coefficient kmax by a waveform symmetry judgment algorithm; if the waveform symmetry coefficient kmax meets the waveform asymmetry requirement, determining that excitation surge current is generated.
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Description

technical field

[0001] The present invention generally relates to transformer protection technology, in particular to a method and device for detecting an excitation inrush current generated when a transformer is switched on with no load, and a braking method and device for an excitation inrush current. Background technique

[0002] In the power system, when the transformer is switched on without load, there will be a momentary high current, for example, 6~8 times the rated current of the transformer. This instantaneous large current that occurs when the transformer is switched on is what is called "magnetizing inrush current" in the field. Therefore, when the transformer is switched on without load, the appearance of the inrush current may mistakenly trigger the differential protection action of the transformer, so that the transformer will automatically trip immediately after the switch is switched on.

[0003] The main reason for the occurrence of "excitation inrush curr...

Claims

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