| Transformer used for power transformation is an important electrical equipment in the power grid;once the transformer fails,it will directly affect the transformation and transmission of power and threaten the safe operation of the grid,causing economic losses to the society,and the serious situation will affect the stability of the society.Therefore,it is of great significance to ensure the safe and stable operation of the transformer in various environments.At present,the combination of mineral insulating oil and paper fiber is the main insulation mode of most transformers.Although mineral insulating oil has good physical and chemical properties and electrical properties,it has low ignition point,flash point and poor biodegradability.Once leaked,it will cause pollution to water source and soil.In recent years,with the enhancement of people's awareness of environmental protection and the deepening of sustainable development,natural ester insulating oil,as a new type of high ignition point insulating medium,has gradually become a research hotspot in the field of insulating materials.In this paper,on the basis of the research status of domestic and foreign experts and scholars on natural ester insulating oil and oil paper insulating system,from the micro point of view,on the basis of understanding the molecular structure of natural ester,the physical and chemical properties and electrical properties of natural ester are analyzed.The dielectric properties of two different oil-based natural esters are studied by the test method,with the emphasis on two natural esters The power frequency withstand voltage characteristics of insulating oil and its oil paper insulation system at low temperature provide data support for the safe operation of natural ester insulating oil transformer in high cold area.The results show that:1)From the microcosmic point of view,on the basis of understanding the molecular structure and chemical composition of natural ester,the basis of choosing natural ester insulating oil to extrude crude oil is put forward.The main physical and chemical parameters of two kinds of natural ester are obtained through experiments.The comparison of the physical and chemical parameters of two kinds of natural ester and mineral insulating oil shows that two kinds of natural ester have good physical and chemical properties as insulation medium oftransformer.2)Oil paper insulation is the most important insulation method of transformer,which provides guarantee for safe and stable operation of transformer.In order to ensure the safe operation of transformers in high cold area,the withstand voltage characteristics of two kinds of oil-based natural ester insulating oil and corresponding oil paper insulation system at low temperature are studied.It is concluded that the breakdown voltage of natural ester insulating oil and oil paper insulation system is very low in the temperature range of-10 ? ? 0 ?.If the oil temperature of the transformer is below-10 ? before putting into operation,it is recommended that the transformer run without load for a period of time,and then run with load after the oil temperature rises to 10 ?.3)The dielectric properties of two kinds of natural esters are measured by the dielectric spectrum temperature / frequency spectrum test system in combination with the relationship between the mesoscopic parameters and the macro parameters of the dielectric properties of insulating materials.The mechanism of the dielectric changes with temperature and frequency is analyzed from the micro point of view.The results show that the two kinds of natural esters have good dielectric properties. |
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