Transformer digital self-adaptive protection device and method based on pressure features

Abstract

The invention provides a transformer digital self-adaptive protection device and method based on pressure features. The device comprises a transient oil pressure feature quantity measuring module, a switching quantity input module, a signal modulation and collection module and a digital core module, wherein the transient oil pressure feature quantity measuring module is connected with the signal modulation and collection module; and the signal modulation and collection module and the switching quantity input module are connected with the digital core module. The transient oil pressure digitalinformation of a plurality of measuring points inside an oil tank is obtained in real time; an action pressure value representing the oil pressure amplitude is obtained through operation; a protectioncriterion and threshold value setting method is built by using the obvious differences of the feature quantity under different operation conditions of a transformer; the reliable fast and sensitive discrimination and elimination of faults inside the oil tank of the transformer can be realized; and no influence is caused by excitation inrush current. Meanwhile, the fault state self-adaptive and threshold value self-adaptive protection scheme is designed so as to accelerate the protection action speed.

Description

technical field [0001] The invention belongs to the field of electric power systems, and relates to a transformer digital self-adaptive protection device and method based on pressure characteristics, which are used for reliable, fast and sensitive identification of internal faults in oil tanks of oil-immersed power transformers. Background technique [0002] As an important component of power transmission, the power transformer will have a serious impact on the reliability and operation stability of the power system once it fails. Especially for large power transformers installed at the hub of the system, because of their high voltage level, large capacity, complex structure, and high cost, damage due to failure will inevitably cause huge economic losses. Therefore, a relay protection device with good performance and reliable operation must be installed according to the capacity and importance of the transformer. [0003] The development of relay protection technology depen...

AI Technical Summary

Problems solved by technology

However, there are two main defects in the principle of transformer current differential protection: first, the excitation inrush current in the excitation circuit when the transformer is closed with no load may cause differential protection to malfunction; second, in the face of single-turn or In the case of weak faults such as short circuit with small number of turns, the differential protection may refuse to operate due to insufficient sensitivity

Under the continuous injection of fault electric energy, the internal pressure of fault bubbles also continues to rise. At the same time, due to the expansion inertia of liquid insulating oil near the fault point, the gas-liquid phase interface between the fault bubble and the surrounding liquid insulating oil will inevitably produce a significant pressure increase. , and spread inside the transformer oil tank in the form of pressure waves, resulting in an overall sudden rise in the oil pressure inside the oil tank

In addition, since the transformer oil tank is not a pressure vessel, the tank is often deformed and cracked under the impact of internal pressure waves

On the other hand, when the transformer has an external short-circuit fault, the fault point is located at the outlet of the transformer, and the impact on the internal pressure of the oil tank is only reflected in the winding vibration caused by the short-circuit through current

At the same time, the change in oil pressure caused by this process is limited since the mechanical strain of the winding will consume a lot of energy

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