A study of harmonic spatial propagation along AC power lines of meshed power systems

Severe harmonics propagation in power systems may result in increased power losses and equipment damages. In this paper, an elliptic formula is derived to analyse the harmonic spatial distribution not only at the substations but also along the power lines or cables and to give a system-wide overview of harmonic levels. It is observed that harmonic distortion along power lines can be higher than that at the busbars and the maximum amplitude of harmonic voltage and current denoted as weak positions along power lines depends on the steady-state harmonic angle difference of voltage and current at busbars, the length of power lines, and the harmonic order. All cases are modelled in detail by analytical geometry and analysed in MATLAB. In this regard, a method to identify the weak positions in terms of maximum harmonic levels in a power system is presented, and its corresponding harmonic orders are determined. The accuracy of the model is tested using time-domain simulations in PSCAD/EMTDC.