Distributed Secondary Control for Islanded Microgrids Considering Communication Delays

Abstract

A distributed control of a Microgrid (MG) depends on the communication network for the exchange of information among the Distributed Generators (DGs). Most of the control schemes consider ideal communication among the DGs; however, in practical systems, delays are inherited in a system that can affect the dynamic performance and even destabilize an MG. Therefore, in this research work, a distributed Secondary Controller (SC) for an islanded MG is designed considering Communication Time Delays (CTDs). Sufficient delay-independent conditions for the robust stability of a buffer-free distributed averaging proportional integral control scheme are proposed. The CTDs are analyzed using the Lyapunov Krasovskii approach. A proposed method synchronizes the frequencies and voltages of the DGs to their respective references while confirming proportionate power sharing in the presence of CTDs. Moreover, different adaptive controllers are designed to update the fixed SC gain parameters to enhance the system’s performance. Finally, the efficacy of the controller is demonstrated through simulation studies that validate its performance against load variation and plug-and-play functionality.

Keywords

• Communication delays
• distributed control
• hierarchical control
• microgrid
• secondary control