Harmonic Analysis of Radial Distribution Systems Embedded Shunt Capacitors

Abstract

Harmonic analysis is an important application for analysis and design of distribution systems. It is used to quantify the distortion in voltage and current waveforms at various buses for a distribution system. However such analysis has become more and more important since the presence of harmonic-producing equipment is increasing. As harmonics propagate through a system, they result in increased power losses and possible equipment loss-of-life. Further equipments might be damaged by overloads resulting from resonant amplifications. There are a large number of harmonic analysis methods that are in widespread use. The most popular of these are frequency scans, harmonic penetration and harmonic power flow. Current source (or current injection) methods are the most popular forms of such harmonic analyses. These methods make use of the admittance matrix inverse which computationally demand and may be a singular in some cases of radial distributors. Therefore, in this paper, a new fast harmonic load flow method is introduced. The introduced method is designed to save computational time required for the admittance matrix formation used in current injection methods. Also, the introduced method can overcome the singularity problems that appear in the conventional methods. Applying the introduced harmonic load flow method to harmonic polluted distribution systems embedded shunt capacitors which commonly used for losses minimization and voltage enhancement, it is found that the shunt capacitor can maximize or minimize system total harmonic distortion (THD) according to its size and connection point. Therefore, in this paper, a new proposed multi-objective particle swarm optimization "MOPSO" for optimal capacitors placement on harmonic polluted distribution systems has been introduced. The obtained results verify the effectiveness of the introduced MOPSO algorithm for voltage THD minimization, power losses minimization and voltage enhancement of radial distribution systems.