A Hybrid AC/DC Microgrid and Its Coordination Control

TLDR

The study proposes a hybrid AC/DC microgrid and coordination control algorithms to reduce multiple conversion stages and enable smooth power transfer between AC and DC links under varying generation and load conditions. The hybrid grid integrates AC and DC networks via multi‑bidirectional converters, connects AC sources and loads to the AC side, DC sources and loads to the DC side, allows energy storage on either link, and operates in grid‑tied or autonomous mode while accounting for wind, solar, temperature, and load uncertainties. Simulations of a small hybrid microgrid in MATLAB/Simulink demonstrate that the coordination control schemes maintain stable operation when the system switches between operating conditions.

Abstract

This paper proposes a hybrid ac/dc micro grid to reduce the processes of multiple dc-ac-dc or ac-dc-ac conversions in an individual ac or dc grid. The hybrid grid consists of both ac and dc networks connected together by multi-bidirectional converters. AC sources and loads are connected to the ac network whereas dc sources and loads are tied to the dc network. Energy storage systems can be connected to dc or ac links. The proposed hybrid grid can operate in a grid-tied or autonomous mode. The coordination control algorithms are proposed for smooth power transfer between ac and dc links and for stable system operation under various generation and load conditions. Uncertainty and intermittent characteristics of wind speed, solar irradiation level, ambient temperature, and load are also considered in system control and operation. A small hybrid grid has been modeled and simulated using the Simulink in the MATLAB. The simulation results show that the system can maintain stable operation under the proposed coordination control schemes when the grid is switched from one operating condition to another.