Virtual Synchronous Machines can help stabilize grids and microgrids with a large penetration of Renewable Energy Sources connected by means of static converters. The thesis focuses on the analytical validation of VSMs, in particular the S-VSM, and carrying out simulations and tests using a microgrid to analyze the real world response of the control strategies. The VSM will also be compared to traditional grid interfaced inverter controls to highlight the differences and improvements of the new generation of grid-tied inverters. In the end the tests will evaluate the capabilities of the S-VSM to perform in islanding mode and its stability during the transition.