On-line monitoring method and on-line monitoring system for axial pressing state of electric power transformer winding

Abstract

The present invention discloses an on-line monitoring method and an on-line monitoring system for an axial pressing state of an electric power transformer winding. A natural frequency of an upper layer wire cake of the winding is extracted from vibration signals of an upper surface of a transformer oil tank according to a characteristic that the natural frequency of the upper layer wire cake of the winding reduces under the action of a stable component of an axial Ampere force, a degradation of the axial pressing state of the winding, namely the reduction of a pre-tightening force, results in the reduction of the natural frequency of the wire cake of the winding, and thereby on-line monitoring the axial pressing state of the large power transformer winding by following and observing a variation trend of the natural frequency. The on-line monitoring system includes a vibration signal acquisition module, a load current acquisition module, an analysis control module, a storage module, an output display module and a sound alarm module, wherein, the vibration signal acquisition module, the load current acquisition module, the storage module, the output display module and the sound alarm module are connected to the analysis control module respectively. The on-line monitoring method and the on-line monitoring system have the advantages of a distinct physical significance and a simple realization way.

Description

technical field [0001] The invention relates to an online monitoring method and system for the axial compression state of a power transformer winding, belonging to the technical field of online intelligent monitoring of the state of power transmission and transformation equipment. Background technique [0002] Power transformers play an important role in power transformation and network interconnection in the power system, and are crucial to the safe and stable operation of the power grid. If the compression state of the transformer winding deteriorates, the axial stability of the winding will decrease, and the ability of the winding to resist short-circuit current impact will be weakened. When the electromagnetic force caused by the short-circuit current exceeds the elastic limit of the transformer winding material, the transformer winding will produce irreversible plastic deformation, that is, winding deformation. When the transformer is running, the winding will be subje...

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Problems solved by technology

Among them, the China Electric Power Research Institute, Shanghai Jiaotong University and Shenyang University of Technology studied the influence of winding pretightening force on the axial vibration characteristics of windings in the de-energized state, and measured the natural frequency of the transformer winding in the de-energized state. The test shows that The first-order natural frequency of the winding is generally between 100Hz-200Hz under different pretightening forces, but because the axial ampere force of the winding contains stable components and AC components, the ampere is not considered in the analysis of the influence of pretightening force on the natural frequency of transformer windings Influence of force stabilization component

[0004] After searching the existing technology, it is found that the Chinese patent application number is 201110275583.5, and the patent name is: an online monitoring method for the working state of transformer windings. The patent collects the vibration signal of the transformer box wall, and compares the 100Hz component amplitude value and the expected value of the transformer box wall vibration model to determine the looseness or deformation state of the winding, but the 100Hz component in the transformer vibration signal does not reflect the natural frequency of the winding; the Chinese patent application number is 201210193931.9, and the patent name is: power transformer core loose Fault diagnosis and preliminary fault location system and method. Although the patent adopts the method of placing three vibration sensors on the upper surface of the transformer oil tank to measure the vibration signal, the patent is used to realize the fault diagnosis of the loose core of the transformer, and cannot realize the axial winding of the winding. Recognition of compression state

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