Due to the loss of power from synchronous generators, grid stability needs to be provided by new inverters with grid-forming (GFM) control. However the integration of GFM inverters to the low-voltage grid is still under discussion. Advantageous is the expected increase of resilience and security of supply of the LV grid during a power outage. Meanwhile, this is in contradiction to the anti-islanding required for grid-following (GFL) inverters for safety and operational reasons. It is expected that the stabilising behaviour of GFM control counteracts with the anti-islanding detection methods used, which are seeking to bring grid voltage and frequency out of limits.

In order to prove this thesis, a power hardware-in-the-loop test grid is set up consisting of a GFM inverter and different GFL photovoltaic inverters connected to an emulated utility grid. The grid is switched off at different power balances between the GFM

and GFL inverter and the islanding event is investigated for various GFM virtual inertia parameters. The tests demonstrate that in

many cases the GFL inverter does not detect the islanded grid when the GFM inverter is connected. However, each commercially

available photovoltaic inverter reacts differently to the islanding event.