Representation of single-pole open conditions in stability studies [of power systems]

The general practice in representing a power transmission line with one phase open in stability studies is to assume that the phase is open at one end only. The error involved in such a representation, especially at EHV voltages with a long line section that is not fully compensated, can be appreciable. It is shown that to represent the effect of single phase open conditions in stability studies accurately the equivalent line parameters should be calculated by considering the line to be open at both ends instead of at one end only. The exact method of representing the phase open condition in positive-sequence network simulations in stability studies is derived. A method of calculating the two-port parameters, as seen from the two openings, given the four-port parameters with ground as a return node, is derived