Decentralized Secondary Control of DGs for an Islanded Hybrid AC/DC Microgrid

Abstract

Islanded hybrid ac/dc microgrids (IHMGs), in which ac and dc subgrids are interconnected via interlinking converters (ICs), have emerged as a promising solution for efficient and zero-carbon power grids. In an IHMG, primary objectives of the secondary control for distributed generators (DGs) are to 1) restore the frequency of the ac subgrid ( $f$ ) and common dc bus voltage of the dc subgrid ( $V^{dc}$ ) to their nominal values; and 2) achieve global power sharing among all DGs throughout the entire IHMG. For conventional secondary control methods of DGs, communication lines of DGs and inter-domain communication lines between DGs and ICs are utilized to achieve the objectives, raising reliability and cost issues. In this study, a novel decentralized secondary control method for DGs in an IHMG is proposed, eliminating the need for communications of DGs and inter-domain communications. The effectiveness of the proposed method was validated through dynamic simulations using Simulink/MATLAB. The obtained results were compared with those of a conventional method.

Keywords

• Decentralized control
• distributed generator
• hybrid ac/dc microgrid
• inter-domain communication
• secondary control