Current blanking method and device of transformer iron core grounding current online monitoring equipment

Abstract

The invention provides a current blanking device of transformer iron core grounding current online monitoring equipment. The current blanking device comprises an iron core grounding current signal sampling conditioning module, a signal harmonic separation module, a separation signal phase shift module, a separation signal amplitude modulation and synthesis module, a current amplification output module, a signal frequency tracking module and a feedback control module. The invention further provides a current blanking method of the transformer iron core grounding current online monitoring equipment. According to the invention, the original current of an iron core grounding current monitoring device in operation can be offset and blanked; the calibrated iron core grounding current monitoring device can easily return to a zero current state; and the accuracy of a calibration process is improved.

Description

technical field [0001] The invention relates to the technical field of high-voltage metering, in particular to a current blanking method and device for transformer iron core ground current online monitoring equipment. Background technique [0002] Transformer core grounding current online monitoring equipment, which can monitor the transformer core grounding current in operation in real time, and timely warn of abnormal working conditions such as multi-point grounding of the core, is currently widely used. The basic principle of on-line monitoring of iron core grounding current is to use the clamp current sensor to monitor the current flowing in the iron core grounding flat steel. When the current increases beyond the warning value, an alarm message will be issued to prompt the operator to further investigate hidden dangers or faults. [0003] According to the requirements of relevant enterprise standards (Q / GDW540.1-2010 "Inspection Specifications for On-line Monitoring Equ...

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Problems solved by technology

The inventors of the present application have found through research that: the above-mentioned on-site verification technology of the capacitive current monitoring device and the lightning arrester leakage current monitoring device can also be transplanted to the on-site calibration of the transformer core ground current on-line monitoring device in principle. However, due to the The grounding current of the iron core is very small, at the milliampere level, and contains rich harmonics; for on-site calibration of such a weak mixed-frequency current, the current measured by the monitoring device itself will greatly affect the accuracy of the calibration

At present, there is no public academic report on the on-site calibration of the iron core ground current online monitoring equipment

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