Message Queuing Telemetry Transport Communication Infrastructure for Grid-Connected AC Microgrids Management

Abstract

In a context with an increasing number of non-traditional power sources, smart inverters function as the main interfaces between distributed energy resources (DERs) and the power bus. This role is even more prominent in microgrids (MGs), where numerous DERs must be controlled and coordinated. For this aim, MGs need to implement suitable communication links since, even in distributed control, the system must compensate voltage and frequency deviations caused by local controllers. Likewise, a communication system is required to optimize its operation. This paper aims to apply the technological advances brought by the Internet of Things (IoT) to the issue of communication within an MG. The work proposes a wireless communication architecture based on the message queuing telemetry transport (MQTT) protocol, accompanied by a set of requirements and specifications to establish a multi-directional information flow between DERs in an MG, and potential energy management system (EMS) or secondary controllers. A laboratory-scale testbed was implemented to demonstrate the operation of an EMS in the proposed architecture. The experimental results showed how current control structures seamlessly integrate with the proposed communication system. Furthermore, it was demonstrated that communication latencies or failures did not comprise the stability of the MG, but only decreased the optimality of the EMS control strategy.

Keywords

• smart inverter
• MQTT
• wireless communication
• microgrid
• hierarchical control
• energy management