Digital gas protection method for oil-immersed transformer based on oil flow velocity characteristics

Abstract

The invention discloses a digital gas protection method for an oil-immersed transformer based on oil flow velocity characteristics. According to the method, first, a digital flow sensor installed on an oil-immersed transformer connecting pipe performs continuous real-time measurement on oil flow velocities in the transformer connecting pipe and transmits velocity information to a digital gas relay; then the digital gas relay judges whether protection is started or not according to oil flow velocity measured values; and if protection is started, a setting value delay action according to velocity-time cooperation is protected. Through the method, protection can be effectively started when the oil-immersed transformer has an internal fault, so that a reliable action is protected; and a malfunction of the oil-immersed transformer in case of an external fault is prevented.

Description

technical field [0001] The invention relates to the technical field of protection of oil-immersed transformers, in particular to a digital gas protection method for oil-immersed transformers based on oil flow velocity characteristics. 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 inte...

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 in my country where the gas protection of 500kV transformers has tripped due to faults outside the area; moreover, the whole process from sensing the flow rate to triggering the protection for traditional gas relays has a long delay , 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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