Equivalent PI circuit for zero-sequence double circuit transmission lines

To accurately represent a transmission line, the equivalent PI circuit is required. This representation is based on the distributed parameter line model and fully considers the fact that the parameters including impedance and admittance are uniformly distributed throughout the entire length of the line. For a single-circuit transmission line or a positive/negative sequence double-circuit line, its equivalent PI circuit based on the distributed parameter line model has been well established in the literature. This paper aims to provide the equivalent PI circuit parameters for the zero-sequence networks of a double-circuit line where there is a mutual coupling between the parallel lines. The derivation is based on the solution of the differential equations in the time-domain. Hyperbolic forms of the parameters of the equivalent PI circuit are resulted. A numerical example is utilized to demonstrate the application of the equivalent PI circuit parameters and compare with the nominal PI circuit parameters.