SF_6/CF_4 作为变压器的冷却和绝缘介质的研究

Investigation of SF 6/CF 4 mixtures as the insulating and cooling medium of gas insulated transformer

城网规模的迅速发展迫切需要无油化的大容量ＳＦ６气体绝缘变压器。采用混合气体作冷却与绝缘介质可以综合解决ＳＦ６气体的散热和液化问题。在研究了混合比例和压力变化对混合气体性能的影响后，提出用ＳＦ６／ＣＦ４混合气体可以代替纯ＳＦ６和ＳＦ６／Ｎ２作为气体变压器的绝缘和冷却介质。当变压器内充入ＳＦ６／ＣＦ４混合气体时，采用离散化的差分模型对其温升分布特性进行理论计算，并与相同条件下充入ＳＦ６／Ｎ２和纯ＳＦ６时的计算相比较，结果表明：采用ＳＦ６／ＣＦ４混合气体不会过分影响线圈温升。研究工作为气体绝缘变压器朝高电压和大容量发展提供了参考依据。

? Fast development of power network in overpopulated urban areas is leading to a strong demand for oilless, non flammable and nonexplosive large capacity SF 6 gas insulated transformers from the viewpoint of accident prevention and compactness of equipment. Applying gas mixtures as the insulating and cooling medium can comprehensively solve the problems of heat dissipation and liquefaction of SF 6 gas. Having studied the significant influence of variations of both mixed proportion and gas pressure on the dielectric and thermal properties of gas mixtures, a SF 6/CF 4 gas mixture is presented instead of SF 6/N 2 gas insulated transformers. The temperature rise distributions of coils are also theoretically calculated by applying discrete differential model when transformer is filled with SF 6/CF 4 gas mixtures. Calculated results show that applying SF 6/CF 4 gas mixtures does not excessively influence coils' temperature rise compared with pure SF 6 gas. The research work presents a reference basis for the development of gas insulated transformers toward both high voltage and large capacity.