Calculation of transient parameters and overvoltages in cable/GIS power systems

In this paper, the present different calculation methods of cable/GIS parameters, including analytical methods, the finite element method, and the subdivision method, are analyzed and compared. With example calculations, suitable methods are recommended. The surface subdivision method is presented for the first time to calculate parameters at high frequencies and is shown to be both simple and convenient. This paper presents the pathological problem that exists at high frequency in the modal transformation of cable/GIS systems. This pathological problem is solved in this paper by removing the pathological elements in modal transformation. With the transient parameters calculated, the influence of the earth on the surge propagation along the cable is also analyzed. The cable sheath is considered as one conductor to reflect the strong effect of the earth. The results of calculations for lightning surge overvoltages in urban cable/GIS systems show that three-phase models should be used instead of one-phase.<>