High penetration and anti-islanding analysis of multi-single phase inverters in an apartment complex

With increasing penetration of multi-inverter photovoltaic (PV) systems into the distribution network, concern is beginning to reemerge regarding the possibility of multi-inverter unintentional islanding. This paper discusses a study to probe anti-islanding and voltage rise issues for a specific hybrid anti-islanding method (common to many commercial inverters) in a proposed high-penetration PV installation at a residential development in Salem, MA. Two sets of studies were run, one involving the specific feeder involved in this installation, and the other a more generic study that deliberately sought the Non-Detection Zone (NDZ) of the hybrid anti-islanding method in the multiple-inverter case. The paper discusses the results of both of these studies, and makes recommendations to assist utilities in deciding when anti-islanding studies might be needed in fielded systems.