Impact of Variations in the Utility Side on the Harmonic Contribution of Customer Installations

In recent years there has been an increasing interest in identification and quantification of the prevailing harmonic source at the point of common coupling (PCC). For this purpose, some indices have been proposed and reported in relevant standards and literatures such as IEC61000-3-6. However, the issue of isolating the customer contribution from variations in the utility-side is still under discussion. The aim of this research paper is to demonstrate the impact of variations in the utility-side (i.e. harmonic impedance and background distortion) on the indices for customer emission assessment. This paper addresses two common indices known as IEC approach and harmonic vector method as well as three further indices. Investigations are simulation-based for line-commutating equipment and measurement-based for self-commutating equipment. Results show inconsistency of customer contribution indices in the case of variations in the utility side.