750kVGIS变电站雷电侵入波过电压的研究

为使模拟计算结果更接近实际,需要研究雷电侵入波过电压计算模型的误差及影响因素,基于输电线路的伏库特性,用简单的电路模型模拟输电线路电晕特性,建立了集中电感、单波阻和多波阻3种杆塔模型;研究了电晕效应对雷电过电压及杆塔模型对变电站雷电侵入波过电压计算结果的影响。利用EMTP计算雷击塔顶和绕击输电线路2种雷击方式下750kVGIS变电站内断路器、电流互感器及变压器等设备雷电侵入波过电压的结果表明,冲击电晕使雷电侵入波产生很大的衰减和变形,和不考虑电晕所得过电压幅值相差约5%;3种杆塔模型算得的结果相差近10%;GIS出线方式等其它因素对过电压值也有较大的影响。

Study on the Lightning Intruding Over-voltage in 750 kV GIS Substation

There are many factors affecting the lightning intruding over-voltage in substation, except impulse corona and the tower model, the mode and length of GIS outgoing line are also the factors. On the basis of the Q-V characteristics of transmission lines, in this paper, a simple circuit model is presented to simulate characteristics of corona on the transmission lines and the effect of corona on lightning over voltage has been studied. Three tower models that is lumped inductance model, single surge impedance model and multi-surge impedance model are built, and the effect of tower model on lightning over voltage has been studied. Considering the influence of every factor,through two types of lightning stroke, that is lightning stroke on the top of a tower and shielding failure, the lightning over-voltages on circuit breaker(CB), current transformer(CT) and transformer are calculated by EMTP when lightning waves intrude into 750kV GIS substation in this paper. The study indicates that corona makes lightning intrusive wave attenuate and distort greatly, so the amplitude and gradient of lightning wave are reduced greatly, the attenuation in the section of ingoing line caused by corona takes up about 5% of the total lightning over voltage. Among three tower models, the over voltage derived from lumped inductance model is bigger than that of single surge impedance, and the over voltage derived from single surge impedance model is bigger than that of multi-surge impedance model. The discrepancy between three models is nearly 10%.