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Method for correct identificating paradrop excitation surge and paradrop fault in transformer protection

A technology for transformer protection and inrush current, applied in the electrical field, can solve the problems of slow differential protection action and hidden dangers of safe operation of transformers.

Inactive Publication Date: 2006-11-29
XUJI GRP +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In this way, when the faulty transformer is air-dropped, the faulty phase is blocked due to the excitation inrush current of the non-faulty phase, which leads to the slow operation speed of the differential protection when the faulty transformer is air-dropped, which brings hidden dangers to the safe operation of the transformer

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  • Method for correct identificating paradrop excitation surge and paradrop fault in transformer protection
  • Method for correct identificating paradrop excitation surge and paradrop fault in transformer protection
  • Method for correct identificating paradrop excitation surge and paradrop fault in transformer protection

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Embodiment Construction

[0035] Describe the detailed content of the present invention in detail below:

[0036] Principle analysis

[0037] When a normal transformer is air-dropped, the differential current waveform is an inrush waveform. Due to the influence of the size and direction of the transformer's remanence and the angle of the voltage when closing, the inrush waveform of the transformer cannot be determined, but the inrush waveform has obvious discontinuity angles. Airdropping the transformer may also cause TA saturation, sometimes causing the waveform to be symmetrical up and down with respect to the time axis, but the TA transient saturation waveform has a plateau. The time-difference current waveform of an air-drop fault transformer is the superposition of the excitation inrush waveform and the fault current waveform, but it is not a simple superposition. When the transformer core works in the saturated region, the current waveform has the characteristics of inrush waveform. When the tra...

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Abstract

This invention relates to a method for identifying air excitation flow and airdrop faults correctly in the protection of high voltage transformers, which selects two watching windows at current waveforms, then utilizes the current in one of the windows to forecast a sine wave, utilizes the probability theory to compute the relative coefficient of the sine wave sequence and that of the windows to differentiate airdrop transformers and the fault ones by the relative coefficient to reach the aim of quickly excising the fault air transformers.

Description

technical field [0001] The invention relates to a method for correctly identifying airdrop excitation inrush current and airdrop fault in transformer protection in the field of electricity Background technique [0002] Correctly identifying the inrush current is an important index to measure the differential protection of high-voltage and ultra-high-voltage transformers. Since the large-capacity transformer has a small inrush current during airdrop, in order to ensure that the differential protection is reliable during airdrop, generally the differential protection The setting of the second harmonic braking coefficient is very small, and the "or" blocking method is used. In this way, when the faulty transformer is air-dropped, the faulty phase is blocked due to the excitation inrush current of the non-faulty phase, which leads to the slow operation speed of the differential protection when the faulty transformer is air-dropped, which brings hidden dangers to the safe operati...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/045
Inventor 张克元张项安杨恢宏余高旺陈海龙徐立明
Owner XUJI GRP