正极性振荡型冲击电压下带尖刺SF6间隙击穿过程的数学模型构建

Construction of Mathematical Model About the Breakdown Process of SF6 Gap With Protrusion Under Positive Oscillating Impulse Voltage

对GIS进行振荡冲击耐压试验有助于发现GIS的内部缺陷故障。对于GIS中较为常见的高压导杆尖刺缺陷,其在正极性振荡冲击电压下的击穿电压较低,但相应的击穿过程尚不是很明确。因此,该文基于SF6气体击穿的物理过程建立一种正极性振荡冲击电压下SF6绝缘间隙击穿过程的数学模型,对SF6绝缘间隙的放电过程进行数值计算。数学模型通过有效电子的产生、流注起始、先导发展3个部分定量描述间隙的放电过程,并考虑空间电荷的影响,阐述先导逐级发展的特性。通过在实体GIS上开展击穿试验,验证模型的准确性。该文所建立的模型可用于对正极性振荡冲击电压下SF6气体绝缘间隙的击穿过程进行数学描述,并对击穿特性进行定量计算。

Oscillating impulse withstanding voltage test on GIS can help to find the internal defects of GIS. As to the common high voltage guide-bar protrusion defect, the breakdown voltage is usually lower under positive oscillating impulse voltage, but the corresponding breakdown process is still not clear. So this paper established a breakdown process mathematical model of SF6 insulation gap under positive oscillating impulse voltage, performing numerical calculations of SF6 insulation gap＇s discharge process, based on the breakdown physical process of SF6 gas. Through the effective electron generation, streamer inception and leader propagation the discharge process of the gap was quantitatively described, influence of space charge was considered and the characteristics of stepped leader was revealed. By conducting experiments on entity GIS, the accuracy of the model was verified. The model established in this paper can be used for the mathematical description of SF6 insulation gap＇s breakdown process under positive oscillating impulse voltage, and the breakdown characteristics can be calculated quantitatively.