Contents I. Introduction
Harmonic source distortions in distribution systems are problems of great concern nowadays. Different approaches for harmonic source detection have been presented in the literature to calculate the harmonic contributions at the common point of coupling. New instruments have been developed for the detection of harmonic sources in power systems [1]. These instruments can detect the source of harmonics even in an unbalanced three phase system. In a generic metering section harmonic sources can be located both upstream and downstream the metering section so that it can be determined that how the supply and load are responsible for harmonic pollution. A Single point strategy based on the comparison of different non active powers can provide useful indications for the detection of the dominant harmonic source upstream or downstream the metering section [2]. The strategy has been tested on IEEE test system and its effectiveness has been proved taking into account the influence of the errors of the measurement transducers [3]. The authors in [4] presented a new strategy which can entirely be implemented in the time domain and can evaluate power harmonics without calculating the amplitudes and phases of the harmonic currents. They proposed another improved strategy for detection of dominant harmonic source which is based only on the separation of the fundamental components from harmonic content of voltage and current [5]. Total harmonic power method is successful in identifying the primary load for the harmonic pollution in a radial system. The signs of total and individual harmonic powers can provide detail information about the harmonic pollution [6]. The harmonic contributions of a customer at the common point of coupling can be determined by separating harmonic currents and voltages into two components [7]. One component is entirely due to supply system and the other is entirely due to the customer. Critical impedance method can correctly detect harmonic sources [8]. The principle of this method is to compare two magnitudes of harmonic voltage sources in the Thevenin equivalent circuit and choose the larger one as the main harmonic source. The authors in [9] showed that it is possible to divide the cost of harmonic pollution among the polluting customers in a fair manner based on single point measurements. A new method for identification of current transformer in presence of harmonic distortion is proposed by the authors of [10]. Experimental datas are presented in [11] to show the impact of current transformers on the accuracy of the harmonic power measurements.
