Safety aspects of decentralized net-coupled electrical generators

The SIDENA-test equipment represents a laboratory low voltage grid connected to the mains via a medium voltage transformer having 400 kVA. It permits investigations of the behavior of different distributed energy generators from various manufacturers when operated at a single grid connection point. The current state of the results of this project on the performance of decentralized energy-generating systems (DEGs) confirm the hypotheses that with a larger number of PV-inverters with an integrated impedance measurement the voltage distortion increases at the grid connection point. ISET's new, patented islanding detection device reduces such system perturbations. Furthermore it was shown that some inverters show a switch-off behavior in certain conditions that can be hazardous to other inverters and loads installed within the distribution network.