特快速暂态过电压及其对主变的影响

Very fast transient over-voltages and their effects on power transformers

由于操作全封闭SF6气体绝缘变电站(GIS)隔离开关而引起的特快速暂态过电压(VFTO)是GIS特有的一种过电压,对变电站内的设备特别是电感类设备如变压器等构成新的影响。该文在简述500kVGIS特快速暂态过电压产生的原因、影响因素、危害及其抑制措施的基础上,以江苏宜兴抽水蓄能电站500kVGIS变电站为例,采用PSCAD/EMTDC软件详细计算分析了多种操作方式下的VFTO。以相关文献的试验结果作为参考,讨论了VFTO对主变的影响。结果表明,由于连接主变与GIS的长电缆明显抑制了出现在主变侧的VFTO,该项目中涉及的VFTO对主变的影响不明显,不会造成主变的匝间绝缘击穿。

Disconnect switch restriking causes very fast transient over-voltages (VFTO) in gas insulated substations (GIS) which can damage power equipment, especially inductance devices in the substations. The VFTO characteristics, origins, and influencing factors were analyzed to quantify the threat and evaluate mitigation methods. A typical 500 kV GIS engineering example was also analyzed. Experimental results in the literature were used to evaluate the effect of VFTO on power transformers. In the example tested in this project, the long power cable connecting the GIS to the power transformer caused the VFTO to have negligible effect on the power transformer.