Power flow in radial distribution systems in the presence of harmonics

Abstract

This paper presents the results of power flow calculations in the presence of harmonics in radial distribution systems
obtained using the decoupled harmonic power flow (DHPF) algorithm. In this algorithm, the interaction among the harmonic
frequencies is assumed to be negligible and hence the calculations are separately performed for every harmonic order of interest. A
detailed methodology for calculating current and voltage high order harmonics, harmonic losses and total harmonic distortion of
voltage of the electrical distribution networks in the frequency domain is presented. The standard backward/forward sweep method is
used for solving the power flow problem at the fundamental frequency. Furthermore, some practical and approximated models of
network components in harmonic analysis are given. The performance of the DHPF approach is studied and evaluated on two standard
test systems with nonlinear loads, the distorted IEEE 18-bus and IEEE 33-bus. Nonlinear loads are treated as harmonic current sources
that inject harmonic currents into the system. The DHPF algorithm is verified by comparing its results with those generated by
software tools for the analysis of transmission, distribution and industrial power systems (i.g. ETAP and PCFLO). Simulation results
show the accuracy and efficiency of the applied procedure for solving the harmonic power flow problem.