Method for predicting hot-spot temperature of transformer winding under low temperature

Abstract

The invention discloses a method for predicting the hot-spot temperature of a transformer winding under low temperature, and the method comprises the steps: firstly building an improved three-thermal-circuit model; carrying out the correction of the improved three-thermal-circuit model in different oil flow cooling modes; comparing a temperature rise value, detected by a temperature measurement sensor, of transformer oil with a temperature value calculated through the corrected three-thermal-circuit model, and correcting a transformer thermal circuit model approaching to the reality; calculating the mean oil temperature of a transformer based on environment temperature through the transformer thermal circuit model approaching to the reality, enabling the mean oil temperature of the transformer to serve as the reference temperature of central oil temperature of the improved three-thermal-circuit model, calculating the top oil temperature of the model, and finally calculating the hot-spot temperature value of the transformer winding. According to the invention, the method is simple in design, is easy to implement, is easy to popularize and implement, provides a basis for the checking of the capability of a transformer for resisting a short-circuit fault, improves the operation safety and stability of the transformer, and is better in economic benefits.

Description

technical field [0001] The invention relates to a method for predicting the hot spot temperature of a transformer winding under low temperature conditions. Background technique [0002] According to relevant meteorological statistics, my country's northeast and eastern Inner Mongolia are frequent areas of extreme low temperature events, and outdoor power transformers will be tested by low ambient temperatures. The physical characteristics of the oil change due to the temperature drop, which will have a relatively large negative impact on the heat dissipation inside the transformer. At low temperature, the heat dissipation performance of the transformer is different from that under normal conditions, so it is of great significance to study the internal temperature of the transformer under low temperature conditions. [0003] At present, the research on the hot spot temperature of transformers is mainly based on indirect measurement methods. Among them, the thermal circuit mo...

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Problems solved by technology

[0005] Although the three-heat circuit model well illustrates the heat transfer process inside the transformer, it does not show the heat exchange process between the heat in the transformer and other factors in nature in the model except for the factor of ambient temperature, such as the temperature of the transformer box. Natural convection heat dissipation, forced convection heat dissipation caused by natural wind, and temperature rise caused by solar radiation

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