Impedance models of multi-circuit multi-voltage overhead power lines

The paper discusses aspects related to the modeling of multi-circuit overhead power lines (HV, EHV), in particular their zero models. The article presents a mathematical model of two-voltage three-circuit overhead line in power system’s structure which includes the impact of lightning conductors, occurrence of bundle conductors and occurrence of differentiation in rated voltage levels of circuits of an overhead line. Moreover, the influence of the lack of symmetrization in such line on the voltages symmetry was examined.