A unified distributed hierarchal control of a microgrid operating in islanded and grid connected modes

Abstract

To guarantee an uninterruptable power supply, a microgrid must be able to operate in both islanded and grid‐connected modes. Hence, it is required to synchronize the voltage phasor of the point of common coupling of the microgrid with the utility grid. Therefore, a distributed cooperative hierarchal control structure is proposed that seamlessly synchronized an islanded microgrid with the utility grid. A proposed method uses a leader‐follower based consensus to regulate the voltage phasor while ensuring proportionate load sharing. A synchronization controller is designed that uses an adjustable parameter to eliminate the voltage magnitude and phase mismatch, and transmit the regulated compensation signal to the leader DGs. The leader DGs transmits these signals to the follower DGs through a cyber‐channels. Moreover, a Massachusetts Institute of Technology rule and Lyapunov function based adaptive controllers are designed to update the secondary control law parameters in case of any disturbance or uncertainty. These adaptive techniques do not require prior knowledge about the microgrid topology, loads, and impedances thus enhancing the system performance. Furthermore, a small signal stability analysis is presented to facilitate the controller parameter design criteria. Finally, the robustness and effectiveness of proposed structure is verified through simulation results in different scenarios.

Enhancing microgrid performance with AI‐based predictive control: Establishing an intelligent distributed control system

“…Hence, there is a pressing need for more comprehensive research to address these critical aspects. References [20][21][22][23][24][25] focus on controllers designed for VaF in a droop-based microgrid control system operating in island mode. These studies emphasize the reduction of reliance on communication networks through the implementation of communication-less control systems.…”

Event‐triggered distributed secondary control for enhancing efficiency, reliability and communication in island mode DC microgrids

“…However, in this control method, communication failures or delays can cause problems in energy quality and energy continuity. If the communication distance is long in a microgrid spreading over a wide area, this causes to increase on the communication cost and the decrease on the grid security [15,16]. In addition, plug and play capability of this control method is weak [7].…”

“…If the number of sources in the microgrid changes, the control algorithm should be changed. In order to eliminate all these problems occurred due to communication failures and delays, distributed hierarchical control methods have been developed [16].…”

“…Thus, neighboring units in the grid can communicate with each other [2]. The controllers in distributed generation units mostly use the dynamic consensus algorithm to obtain the global average estimates using local and neighbor estimates [16]. In this algorithm, providing the communication of neighboring units is sufficient to achieve the control of whole microgrid.…”

“…In island mode microgrids, the distributed hierarchical control generally uses the primary and the secondary controllers [16]. Primary control operates locally and consists of the inner and the droop control loops [17,18].…”