Effects of load unbalance on multipoint measurement techniques for assessing the responsibility for PQ degradation

The problem of locating the sources of the harmonic distortion in power networks is still a critical task. Several methods based on multipoint measurement techniques have been recently proposed in the literature for harmonic pollution monitoring. The main goal of this study is to compare the two most powerful tools designed for this purpose and to evaluate their behavior in the presence of either balanced or unbalanced polluting loads. In this paper the results of both computer simulations on an IEEE test network and simultaneous measurements on ad-hoc experimental benchmark power system are presented to highlight the strong interaction between distortion and unbalance.

I. Introduction

ANY deviation of voltage and current characteristics from sinusoidal, symmetrical conditions and nominal frequency is commonly referred to as a Power Quality (PQ) issue. Due to several and well-known causes, PQ issues are widely present in the electrical networks. Therefore, measurements oriented to assess the problem origin, to attribute the responsibility for PQ degradation and, finally, to quantify the degradation itself have great interest in a competitive market.