A system and method for overload protection of substation transformers based on time-varying power window

Abstract

The invention discloses a station transformer overload protection system based on a time-varying power window, which includes a power supply module, a sampling module, a decoding module, a signal switching module, a processing module, a setting module, an output module, a tripping and operating pressure plate, and a cooling device; the decoding module and the sampling module are connected to the signal switching module; the signal switching module and the setting module are connected to the processing module, and the processing module is connected to the output module; the output module is connected to the tripping operation pressure plate and the cooling device connect. The invention provides a substation transformer overload protection system and method based on a time-varying power window, which is compatible with IEC61850 standard digital signal and analog signal input, and conforms to the trend of intelligent substations. In a word, the present invention has the advantages of being compatible with analog and digital signal input, strong anti-interference, rapid and accurate response, intelligent response to faults, and the like.

Description

technical field [0001] The invention relates to a station transformer overload protection system and method based on a time-varying power window, and belongs to the technical field of electric power protection equipment. Background technique [0002] At present, substation transformers undertake the task of providing AC power for the control, lighting, DC charging device, maintenance power supply of equipment in the substation and the daily use of electricity for personnel inside the substation, which plays a vital role in ensuring the safe operation of substations and power systems. . If the substation transformer fails, it will directly cause serious impacts such as the inability of the substation control equipment to work and the difficulty in carrying out the maintenance of the power system, thereby expanding the scope and time of the power system failure within this period. Therefore, the safe and reliable operation of station transformers is of great significance. ...

AI Technical Summary

Problems solved by technology

[0003] With the application of electric power more and more widely, the load of the substation is also increasing. However, the capacity of the transformer used in the substation is fixed, and the expansion of the substation will lead to a problem that cannot be solved by the existing transformer protection for the station: the definite time limit overcurrent protection of the transformer used in the station is based on Maximum load current setting, the setting coefficient is greater than 1, that is, the protection will only operate when the rated load current is higher than a certain value

The increase in the load of the station transformer may cause the long-term operation of the station transformer slightly less than the protection action value, or the fault duration is not long enough to cause the protection action

However, when the transformer is operated at a state higher than the rated load for a long time, the accumulated thermal effect will cause temporary or even permanent damage to the transformer insulation and structure, and may cause the transformer to burn out in severe cases; in addition, it will also reduce the insulation life of the transformer. According to GB / T 1094.7-2008 Oil-immersed Transformer Load Guidelines: Every time the hot spot temperature is 6 degrees higher than the rated value, the rated life of the insulating material will be halved

In short, the existing station transformer protection cannot provide accurate and effective protection for the long-term operation of station transformers slightly less than the protection action setting value, or the fault duration is insufficient.

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