Comparison of harmonic emission in LV side of a large grid connected PV power plant

The use of solar photovoltaic (PV) in distribution networks has increased considerably in recent years. Although they have many advantages, PV systems can also result in complex power quality issues in distribution networks, like harmonic distortion, that can interfere with loads and controllers. Harmonic emission from different inverters and their aggregation is thus of interest. In this work, harmonic emission of two PV string inverters and two substations operating in a large PV power plant is presented. The distribution of the full range of current harmonics is analyzed, as well as the correlation between the values of each harmonic and the power level produced, by the inverter or substation, and the correlation between voltage and current harmonics. Significant differences are observed in the harmonic emission of the inverters, despite being under the same operating loading and grid conditions. The results obtained for the substations are in line to those for the inverters. This study was performed in a grid connected 12 MW PV power plant operating in Europe.