Simulation and experimental study of multi-inverter islanding

Increased concern over the possible loss of islanding detection by inverters in multi-inverter situations has spurred deeper investigation into this area. This study looked into the AC array configuration (inverters tied to a low-impedance bus with no interconnecting impedances) of photovoltaic inverters both with simulation and lab experiments to see what if any effect the number of inverters in the island would have on run-on times. A MATLAB/Simulink model of a Teslaco inverter was used for the simulation tests and six 250 W inverters were built for the lab tests. Both simulation and lab tests revealed an initial increase in run-on times for two-inverter islands but then a decrease to single inverter levels and even slightly shorter for larger islands. This study gives experimental validation to the simulation model and suggests that the anti-islanding performance of an all-Teslaco-inverter island does not degrade in the AC array configuration.