Digital transformer gas relay protection method

Abstract

The invention discloses a digital transformer gas relay protection method. The method comprises the following steps: 1) installing a digital electromagnetic flowmeter and a pressure transmitter; 2) connecting to a comprehensive protection measurement and control device through a shielding communication line; 3) measuring instantaneous flow Q and pressure P in real time, and setting an excess flowconstant value as Qset and an excess pressure constant value as Pset; (4) when Q is larger than Qset and P is larger than Pset, enabling the comprehensive protection measurement and control device tosend out a protection action signal, a high-voltage side circuit breaker and a low-voltage side circuit breaker of the transformer being tripped at the same time, and when only one is larger than a set value, enabling the comprehensive protection measurement and control device to only send out a protection starting signal of corresponding flow or pressure and give an alarm; and 5) enabling the comprehensive protection measurement and control device to communicate with a background host. The gas relay protection of the transformer designed by the invention is more accurate, misoperation causedby earthquakes or poor contact of contacts is avoided, confirmation is carried out by adopting two signals of flow and pressure, and the reliability of action is improved.

Description

technical field [0001] The invention relates to the technical field of transformers, in particular to a digital transformer gas relay protection method. Background technique [0002] The traditional transformer gas relay has a mechanical structure and is an important non-electrical protection device for the transformer. It is installed in the pipeline between the oil conservator and the oil tank of the transformer. It uses the internal fault of the transformer to decompose the oil to generate gas or oil When the current surges, the contact of the gas relay will be activated, the designated control circuit will be connected, and a signal alarm will be issued in time (light gas) or the protection element will be activated to automatically cut off the transformer (heavy gas). [0003] Light gas is mainly reflected when the gas decomposed by oil rises into the gas relay during operation or slight fault, the air pressure makes the oil level drop, the opening cup of the relay fall...

AI Technical Summary

Problems solved by technology

(2) Short circuit between turns, short circuit between turns and iron core or sheath

(3) Iron core failure (burning due to heat)

(4) Oil level drop or oil leakage

(5) Poor contact of tap changer or poor wire welding

[0006] Disadvantages of existing gas protection: In recent years, the development of gas relays has been relatively slow, which is likely to cause misoperation of the main transformer. The main disadvantages are: (1) Accurate setting cannot be achieved. Due to the mechanical structure, special instruments are generally used for setting, and the setting The process is relatively complicated, and fine tuning cannot be performed; (2) After long-term operation, the contact may not be able to move at critical times due to poor contact; (3) The performance of gas protection against external interference is poor, such as when an earthquake occurs. It is easy to malfunction, and generally occurs when an earthquake above magnitude 5 occurs. (4) The problem of oil protection cannot be solved well when the gas relay is installed or the gas relay cannot be well waterproofed, resulting in oil leakage and corrosion of cable insulation or relays Misoperation caused by water ingress; (5) The action time is longer

The traditional Buchholz relay also has the problem of too long delay in the whole process from the fault to the tripping of the trigger protection, and may miss the optimal tripping time. Once a serious inter-turn short circuit occurs inside the transformer or an arc short circuit fault occurs inside the bushing, the arc energy of the fault will rapidly increase. Release, the gas relay installed at the connecting pipe of the oil conservator is usually difficult to sense the change of the oil flow surge in time, the traditional gas relay is too late to act, and at this time the wall of the fuel tank near the fault point has already undergone plastic deformation, cracks or even exploded

Therefore, it is urgent to design a digital transformer gas relay protection method to solve the problems that the existing gas protection cannot achieve accurate setting