不同气压下两种缺陷的SF6负极性直流局部放电分解特性

Decomposition Characteristics of SF6 at Negative DC Partial Discharge by Two Typical Defects Under Different Pressure

为了探究不同气压下自由金属微粒与金属突出物在引起负极性直流局部放电（PD）导致SF6特征组分的差异,在搭建SF6直流局部放电分解实验平台的基础上,开展了不同气压下SF6 PD分解特性实验研究,获取了SF6分解特征组分随压强的变化规律。研究表明：在2种缺陷下,SF6会发生分解生成SO2F2、SOF2、CO2、SO2 4种稳定的分解产物,金属突出物缺陷下各分解组分生成量浓度随着气压的增加而逐渐减少,并呈现不同的变化趋势。自由金属微粒缺陷下,SOF2、CO2和SO2随着气压的增加几乎不变,SO2F2随着气压的增加而快速减少。有效量浓度比值c（SO2F2）/c（SOF2＋SO2）随气压的增加逐渐减少,在对GIS进行故障诊断时,需要对气压造成的影响进行校正;c（CO2）/c（SO2F2＋SOF2＋SO2）随气压逐渐增加,并在0.3 MPa后达到稳定,对气压处于0.3～0.4 MPa的气体绝缘设备进行故障诊断时,可以不考虑气压对c（CO2）/c（SO2F2＋SOF2＋SO2）的影响。

In order to explore the influence of different atmospheric pressure on the decomposition characteristics of SF6 under partial discharge at Negative DC initiated by free metal particles and metal protrusion defects, we experimentally studied the SF6 partial discharge（PD） decomposition characteristics under different atmospheric pressures based on the DC experimental platform of SF6 component decomposition. The variation of each characteristic component with pressure was obtained. The research shows that,under the PD of negative DC condition, SF6 will decompose to produce four stable decomposition products（SO2F2, SOF2, CO2, and SO2） under two typical defects. The concentration of these four components decreases with the increase of pressure in metal protrusion defect and shows different change trend. Under the defect of free metal particles defect, SOF2, CO2 and SO2 are almost unchanged with the increase of pressure, and SO2F2 decreases rapidly with the increase of pressure. The effective characteristic ratio of c（SO2F2）/c（SOF2＋SO2） gradually decreases with the increase of atmospheric pressure and its modification of the pressure effect is needed, when GIS is used for fault diagnosis. The effective characteristic ratio of c（CO2）/c（SO2F2＋SOF2＋SO2） gradually increases with the increase of gas pressure and reaches the stability after 0.3 MPa. Therefore, when the GIS is used for fault diagnosis whose gas pressure is in range of 0.3~0.4 MPa, the effect of atmospheric pressure on the effective characteristic ratio of（CF4＋CO2）/（SO2F2＋SOF2＋SO2） can be neglected.