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.