Oil flow velocity variation-based oil immersed transformer digital non-electricity protection method

Abstract

The invention relates to an oil flow velocity variation-based oil immersed transformer digital non-electricity protection method. The method comprises steps of first, performing continuous real-time measurement on flow velocity of oil in a connection tube by a digital flow velocity sensor installed at a connection tube of the oil immersed transformer; then determining whether a velocity variationcalculation procedure is started by a digital gas relay by using received oil flow velocity data; if yes, calculating oil flow velocity variation, and comparing measurement value of variation with setting value of variation; and determining whether protection acts according to a comparison result. The method is started effectively when the oil immersed transformer has an internal fault, and protects reliable actions; and prevents the oil immersed transformer from acting wrongly when the oil immersed transformer has an external fault.

Description

technical field [0001] The invention relates to the technical field of protection of oil-immersed transformers, in particular to a digital non-electrical protection method for oil-immersed transformers based on oil flow velocity variation. Background technique [0002] Since the 1920s, transformer gas protection has become the mainstream non-electrical protection method for transformers. As a supplement to transformer electric protection, it is mainly used to deal with internal short-circuit faults of transformers. Compared with the electrical quantity protection of the transformer, the non-electrical quantity protection that reflects the fault gas is more comprehensive, directly responds to the operating state of the protected object, and has unique advantages in terms of sensitivity. [0003] The gas relay of the original oil-immersed transformer is a mechanical protection. The protection principle based on the information of the oil flow velocity is that in the case of an...

AI Technical Summary

Problems solved by technology

However, due to the long-term lack of sufficient attention and research, the gas relays currently used in the system have defects such as low reliability, threshold value based on experience, insufficient mechanical structure, and insufficient quick action. occur

According to statistics, in recent years, there have been several accidents where the gas protection of 500kV transformers has tripped due to faults outside the area; moreover, because the traditional gas relay has a long delay in the whole process from sensing the flow rate to triggering the protection to trip , It is possible to miss the best tripping time. Once a serious turn-to-turn short circuit occurs inside the transformer or an arc short circuit fault occurs inside the bushing, the energy of the fault arc is released sharply. It is usually difficult for the gas relay installed at the connecting pipe of the oil conservator to feel the oil flow in time. The surge changes, the traditional gas relay has no time to act, and at this time the wall of the fuel tank near the fault point has already undergone plastic deformation, cracked or even exploded

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