A dynamical multi-input/multi-output network formulation for stability analysis in AC microgrids

Nowadays, we have witnessed a significant increaseof renewable sources across the existing power grids, as aresult of the undeniable need to mitigate the effects of environmental pollution and assist the economic development of countries around the globe. However, due to the lack of rotational inertia and their intermittent nature, renewables have also increased the severity of the occurring disturbances and instability phenomena, which in turn place a demand for more accurate modeling of the network and the power system components. In this paper, we propose a novel network formulation for AC microgrids that allows the consideration of less conservative conditions for the network, while allowing the adoption of higher order inverter-based generation dynamicsand facilitating the stability analysis and control. In particular, we formulate the network as a dynamical multi-input/multi-output system, which we show is both stable and passive, even if the network’s dynamic and lossy nature is taken into account. We then briefly discuss the opportunities and the advantages offered by the proposed approach and provide useful guidelines for a more accurate modeling of power system components.Finally, we verify the proposed network formulation through a numerical application on the Four Machine Two Area Kundur test system and several simulations on typical Medium Voltage (MV) distribution lines.