三相同壳结构GIS快速暂态过程模型构建和参数计算

数值计算模型和参数的确定,是三相同壳结构GIS快速暂态过程行波分析的基础.该文给出了三相同壳结构GIS快速暂态过程数值计算模型的构建方法.由于三相同壳结构GIS的最大特点是A、B、C三相之间存在电磁场耦合,模型的核心是电感矩阵和电容矩阵.分析表明,电感矩阵和电容矩阵中的所有元素,取决于GIS内导体半径和三相导体的偏心距离与GIS外壳内半径的相对比例.对于一般的三相同壳结构GIS,电感矩阵和电容矩阵的非对角线元素与对角线元素之比通常小于20%,对角线元素对快速暂态过程起主导作用;当忽略非对角线元素的作用时,可得到三相同壳结构GIS快速暂态过程的单相导体简化模型,以便对快速暂态过程进行定性的分析.但要对三相同壳结构GIS中VFT过电压进行定量分析,还应采用三相模型.

TRANSIENT PARAMETERS AND NUMERICAL CALCULATION MODEL ON VFT IN THREE-PHASE ENCLOSED GIS

Transient parameters and numerical calculation model are fundamental to evaluate the traveling wave on very fast transients in three-phase enclosed GIS.The numerical calculation model and the correlative transient parameters were emphatically analyzed.Because of the coupling between phase A,B,and C,a surge impedance matrix was introduced,which is equal to the product of a capacitive matrix and a inductive matrix.Furthermore,it can be seen that elements at diagonal of these matrixes are much larger than other ones,and which is of a dominant position on very fast transients.It means that the numerical calculation model to three-phase enclosed GIS can be replaced with a single-phase simplified model,which is especially useful to understand some basic aspects of very fast transient process.Considering the amplitude of very fast transient overvoltages (VFTO),the three-phase models are still necessary.