Voltage imbalance analysis in residential low voltage distribution networks with rooftop PVs

The installation of domestic rooftop photovoltaic cells (PVs) are on the rise due to feed-in tariff and changes driven by environmental concerns. Even though the increase in the PV installation is gradual, their locations and ratings are often random. Therefore, such single-phase bi-directional power flow can have adverse effect on the voltage imbalance of a three-phase distribution network. In this paper, a voltage imbalance sensitivity analysis and stochastic evaluation based on the ratings and locations of single-phase grid-connected rooftop PVs in a residential low voltage distribution network are presented. The stochastic evaluation, based on Monte Carlo method, predicts a failure index of non-standard voltage imbalance in the network in presence of PVs. Some improvement methods are discussed and a new improvement method based on PV converter control is proposed.

► Voltage unbalance sensitivity analysis was studied in the LV distribution network as the result of domestic rooftop photovoltaic cells (PVs). ► It was proved the PVs can increase voltage unbalance if they are installed at far end of feeder or have higher ratings. ► The efficacy of three conventional and a new proposed method were verified for voltage unbalance reduction.