Reliability of approximation function method for modelling of power lines in electric power systems

This article deals with the calculation of capacitances for double-circuit power lines by the approximation function (AF) method and the reliability of this approach when used in transient state simulations in electric power systems. Standard procedure for computing the capacitances to earth and phase-to-phase capacitances is described along with its implementation into mathematical models of power lines within available simulation softwares. Next, the principle of alternative AF method is introduced and proposed for such simulation tools, which exclude the use of the standard approach. For AF method, its accuracy is determined along with possibilities for its simplification and reliability.