Hidden Protection Challenges of Unbalanced Distributed Networks for Higher Concentration of Distributed Energy Resources

Integration of the distributed energy resources (DERs) has empowered the electric power utilities to meet the increasing load demands efficiently at the reduced cost. Despite several benefits, there are some hidden protection challenges due to the large-scale integration of DERs with unbalanced distribution networks (DNs), which have not been properly addressed in literature. This research work investigates the impacts of higher concentration of DERs on the voltage swelling of the unfaulted phases during fault events for different DERs penetration level. Increase in voltage unbalance of real DNs having unbalanced voltage profile has been analyzed for uneven allocation of single-phase rooftop photovoltaic (PV) units. Impact of the grounding strategies of DERs on the operation of different types of protection strategy has been assessed for different grounding impedance followed by the mitigation strategy.