SF_(6/)N_(2)混合气体雷电冲击放电特性及协同效应研究

Analysis on Discharge Characteristics and Synergistic Effect of SF_(6/)N_(2) Mixed Gas Under Lightning Impulse

SF_(6/)N_(2)混合气体是一种简便有效的SF;环保化措施,已逐步应用于GIS等气体绝缘电力设备中,全面研究雷电冲击下的放电特性及协同效应,可以为绝缘设计及气体参数选择提供依据,具有重要的学术研究与工程应用价值。为此开展了SF_(6/)N_(2)在稍不均匀场和极不均匀场中正负极性雷电冲击放电特性与协同效应研究。发现在稍不均匀场中,正负极性雷电冲击均呈协同效应,负极性下更显著;随电场不均匀度增加,协同效应类型从协同效应向负协同效应转变。协同效应系数C法并不能完整描述SF_(6/)N_(2)的协同效应与负协同效应,提出了一种适用的归一化系数h方法,量化表征了电场不均匀度、电压极性、气压和SF;体积分数的影响,提出了GIS绝缘设计时最优SF;体积分数为20%~25%等建议。

SF_(6/)N_(2) mixed gas,which is used as a simple and effective environmental protection measure for SF;,has been gradually applied to gas insulated power equipment such as gas insulated switchgear(GIS).A comprehensive study on discharge characteristics and synergetic effect under lightning impulse can provide a basis for insulation design and gas parameter selection,which has important academic research and engineering application values.In this paper,the discharge characteristics and synergistic effect of positive and negative polarity lightning impulse in quasi-uniform and highly inhomogenous electric field of SF_(6/)N_(2) mixed gas were studied.It is found that,in a quasi-uniform electric field,there is a synergistic effect which is more significant under negative polarity.As the electric field non-uniformity increases,the type of synergistic effect changes from the synergistic to the negative synergistic.The method of synergistic effect coefficient C cannot fully describe the synergistic effect and negative synergistic effect of SF_(6/)N_(2),therefore,an appropriate method of normalization coefficient h is proposed to quantitatively characterize the influence of electric field non-uniformity,voltage polarity,gas pressure and SF;volume fraction.Some suggestions such as the optimal SF;volume fraction of 20%~25%in GIS insulation design are proposed.