An Approach to the Design of Stable Distributed Energy Resources

Microgrid is some part of the electric grid that may disconnect and operate autonomously, therefore it is becoming a broadly discussed theme in the ecosystem of the distribution domain. In this context, distributed generation and distributed storage may function cooperatively towards balancing energy supply and demand, as well as managing system stability and power quality. Power electronics play a very special role in this evolution since several loads are turning to be powered by some sort of electronic circuitry. In this decentralized scenario, system reliability and stability turn to be very important subjects. The interconnection stability of inverters can be addressed via its input impedance characteristics, which can be shaped to be in equilibrium with the grid. This work explores a scenario where a microgrid first operates stably when connected to the main grid. However, when islanded, the system becomes oscillatory and stability is degraded. Finally, by means of simple controller adjustment obtained throughout impedance analysis, the microgrid stabilizes.