LV Harmonic Analysis of Single-Phase Rooftop Solar PV Systems with Non-Linear Loads

Grid-connected photovoltaics (PV) systems in low voltage
$(\pmb{L}\pmb{V})$
networks are becoming viable due to feed-in-tariffs or net-metering provisions. However, the legacy distribution systems are typically designed for unidirectional power flows from substations to consumers. Therefore, the bidirectional power flows due to grid-connected solar PV systems impact the voltage levels and introduce harmonic distortion in the LV feeder, particularly in weak grids with non-linear loads. The effects of significant non-linear loads on LV power quality are assessed at the point of common coupling (PCC) in this paper. To analyze total harmonic distortion in the current (THD
i
) at PCC, three examples of (low to high) solar PV penetration are evaluated using practical feeder data in a weak grid setting using the radial IEEE-34 bus system. Results show lower power losses with solar PV systems installed at alternate nodes (50% PV penetration) in the LV network. In addition, the per unit voltages of the overall system gets significantly improved, with none of the buses critically and marginally loaded due to solar generation.