Harmonic signature for diagnosis purposes in unbalanced distribution systems

Abstract EN

In this paper, distorted and unbalanced three-phase bus voltages (DUTBV) of distribution systems are analyzed by means of symmetrical harmonic components (SHCs).

A new method which characterizes the dual behavior of unbalance and harmonics on steady state distribution system operations is presented.

The SHCs of DUTBV are deduced for a whole range of harmonic orders of interest by the use of three matrices’ transformations.

Each matrix is applied to a sub-set of harmonic orders of which the corresponding balanced three-phase quantities rotate in the same sequence.

The unbalanced voltage phasors abc at each hth harmonic order are then transformed to three new phasors called balanced, first unbalanced, and second unbalanced.

Their representation in Fourier series allows us to identify a harmonic signature of DUTBV in analytical or graphical ways.

The method is applied to typical threephase distribution systems.

The obtained results confirm the efficiency of the proposed method for power quality monitoring and reporting and it can be used as a powerful diagnosis tool.