Research On Calculating Winding Temperature Fields Of Non-Encapsulated Dry-Type Transformer

Dry-type transformers have the advantages of small size, low loss, pollution-free and highreliability. Based on these advantages of dry-type transformers, some places that requirefireproof and safety use dry-type transformers instead of oil-immersed transformers. As thedry-type transformers use air to cool the winding, the heat transfer of oil is better than air,therefor the winding of dry-type transformers is easier to be heated. If the winding temperature istoo high, the life of the transformer will reduce. Therefore, accurate calculation of dry-typetransformer winding temperature, calculate the average temperature rise and the hottesttemperature of transformers is important. In this paper, I first calculate the airway flow and thencalculate the dry-type transformers winding temperature.This article assumes that the transformer is three-phase symmetrical, temperature gradientalong the winding does not change in the circumferential direction, so the dry-type transformerscan be simplified to physical model of two-dimensional symmetry. The velocity and temperaturefield of various types of dry-type transformers are simulated using the CFD software of Fluent,identify the air flow pattern in the airways. According to the gas flow pattern to calculate the gasflow. Airway flow in the horizontal flow is complex, generally divided into two parts, that the airnot through the level of airway and through it. Using the methods of resistance balance, loss ofpressure is equal to calculate the level of airway. By calculating the total flow resistance withinthe transformer and analyzing the characteristics of the top and the bottom of the fan, calculatethe total ventilation.In this paper, the gas in the dry-type transformers was calculated as compressible gas.Consider the pressure and temperature of the gas compressibility factor, calculate the gas densityand flow in the actual operation, this has a major significance in accurately calculate thetemperature field.In this paper, VC + + language is used to compute the flow of dry-type transformer andwinding temperature distribution. Using MATLAB language to write the software that candirectly calculate the temperature field. This software can calculate temperature of different typesof dry-type transformer, and can display the winding average temperature rise, the hottesttemperature, the hottest location, the whole and any winding temperature distribution through thecloud chart and graph.The temperature that through the software to calculate is consistent with the experimental.In a certain sense, this calculation method has some significance in solving the temperaturedistribution and raising the level of thermal design of the transformer.