Performance of virtual synchronous machine in autonomous mode of operation

Lack of inertia in inverter dominated utility grids and smart microgrids is a serious issue that needs to be tackled and to enable larger integration of renewable energy sources, which are usually interfaced to the grid using power electronic converters. Recently, it has been proposed to embed the dynamics of conventional synchronous machines into power electronic converters to operate them as virtual synchronous machines or synchronverters. Since, the power electronic converters do not have rotational inertia, the electrical energy storage provides the virtual inertia to the virtual synchronous machine. Although a virtual synchronous machine is physically a power electronic converter, its operation is governed by the mathematical equations of a synchronous machine. Virtual synchronous machine based inverters may play a major role in future microgrids since it can impart the inertial response to weak grids during sudden frequency transients. The inverters in a microgrid should be capable of operating in autonomous mode in addition to the grid connected mode. In this paper, the performance of a virtual synchronous machine based inverter operation in autonomous mode is analyzed. The simulation is done using MATLAB/Simulink and the simulation results are validated with the hardware experiments using OPAL-RT real time simulator.