Comparison of frequency domain models for assessing the harmonic emissions of low voltage photovoltaic systems

The proliferation of photovoltaic (PV) systems connected to low voltage (LV) distribution networks can have detrimental impacts on waveform distortion. This is caused by the power electronic interface, with voltage source converter (VSC) technology being by far the most prevalent. As such, proper emission models, which can account for the non-linear operation of VSCs used in PV systems have to be developed and investigated for the assessment of harmonic distortion in LV networks. This paper compares different frequency domain models (FDMs), specifically, methods based on frequency coupling matrices and an analytical method based on a harmonically coupled impedance matrix, for the type of single-phase PV systems typically found in LV distribution networks. Two case studies are presented to compare the models in terms of computational complexity and accuracy, with results showing that models accounting for the interaction between same order harmonics are sufficiently accurate.