0.1～0.25MPa气压下二元混合气体SF_6-N_2和SF_6-CO_2的击穿特性

Breakdown Characteristics of Binary Gas Mixtures SF_6-N_2 and SF_6-CO_2 Under 0.1～0.25 MPa Atmosphere Pressures

柜式气体绝缘开关设备(cubicle gas insulatedswitchgear,C-GIS)由于其全可靠性能高、小型化等特点在电力系统中得到广泛的应用。但由于C-GIS开关柜的主要绝缘介质SF6气体具有较强的温室效应,且其成本较高,迫切需要减少或不用SF6气体。针对C-GIS开关柜较低的气压条件,探讨SF6混合气体替代SF6的可行性。采用圆形平板电极模拟均匀场,研究均匀场、较低气压(0.1~0.25 MPa)下SF6与N2、CO2两种气体的二元混合气体在不同配比、不同电压形式(工频和负极性雷电冲击)作用下的击穿特性。试验结果表明,气压在0.25 MPa以下时,适当增大SF6混合气体的压强可以使其达到纯SF6相同的绝缘强度,为新型C-GIS开关柜的设计制造提供了关键的试验依据。

Owing to its high reliability, security and small size, the cubicle gas insulated switchgear （C-GIS）, in which the SF6 gas is utilized as the principal insulating medium, is widely adopted in power system. However, due to high cost and strong greenhouse effect of SF6, it is urgently needed to reduce the amount of SF6 used in C-GIS or not to use it. According to the lower pressure inside C-GIS cabinet, the feasibility of replacing pure SF6 gas by gas mixture composed of SF6 is researched. In th^s research, circular plate electrodes are adopted to simulate uniform electric field and the breakdown characteristics of binary gas mixtures of SF6-CO2 and SF6-N2 under different gas mixing ratios and different forms of voltages, namely the power frequency voltage and negative polarity of lightning surge, in uniform electric field with lower atmosphere pressures within the range from 0.1 MPa to 0.25 MPa inside C-GIS cabinet are respectively researched. Test results show that when atmosphere pressure is lower than 0.25 MPa, the insulation strength of gas mixture can reach to the same as insulation strength of pure SF6 gas by raising the atmosphere pressure of SF6 gas mixture appropriately. Results of this research offer key teat basis for the design and manufacture of new type of C-GIS cabinet.