Networked Control of Distributed Energy Systems in Dispatchable Microgrids: System Modeling and Stability Considerations

Inverter-interfaced distributed energy systems have been spreading over low-voltage electric grids to achieve higher integration of renewable sources while offering adjustable controllability over power conversion. In addition, due to their remote control capabilities that support a networked system framework, such inverters play an essential role from the perspective of dispatchable microgrids. These are power systems of limited size incorporating information and communication technology infrastructures. By managing network-controlled inverters, it is possible to regulate the power dispatchability of microgrids, allowing them to flexibly exchange power with the upstream grid as needed flexibly. Nonetheless, the control modeling and stability concerns of inverters forming a networked system within such a perspective lack discussion in the literature. Hence, this paper proposes a generic system model for a dispatchable microgrid, considering that a central controller steers inverters under a networked control framework. Moreover, stability considerations are presented, highlighting the impact of communication delays on the microgrid operation and indicating that multiple aspects still need to be investigated in future research.

I. Introduction

Sustainability motivations have been imposing significant changes to the energy sector since the past decades, resulting that more and more renewable-based distributed energy resources (DERs) have been inserted into low-voltage electrical grids [1]. The grounds of this energy transition lie on the attainment of flexible management over the power conversion processed by such DERs [2], besides being motivated by the advantage of energy decentralization, which alleviates the power delivery burden of large centralized power plants. Additionally, in general, DERs are interconnected to the grid by means of power electronic inverters, making use of control strategies as well as information and communication technology (ICT) infrastructures to: i) inject active power into the grid; ii) offer ancillary service functionalities [3]; and iii) also provide support to remote control capabilities [4].