Decentralized Control for Modular Multilevel Interlinking Converter in Standalone Microgrid Operation

Abstract

This paper presents a decentralized modular interlinking converter (IC) for a hybrid microgrid (HMG) operating in standalone mode. The proposed IC is designed using a modular structure, where each module consists of a local controller and four half-bridge submodules. Unlike conventional centralized control approaches, the proposed method enables each module to exchange only local phase angle information with neighboring modules in the same and adjacent phases, reducing communication overhead while maintaining synchronization. The space vector pulse width modulation (SVPWM) technique is employed to generate optimized switching signals for each module, ensuring precise and coordinated operation. This decentralized control strategy allows the IC to facilitate bidirectional power exchange between the DC and AC buses, dynamically responding to variations in AC load demand. The effectiveness of the proposed IC is evaluated in terms of power conversion efficiency, voltage regulation, and frequency stability. A key feature of the system is its plug-and-play capability, allowing seamless addition or removal of modules without requiring a system shutdown. The HMG experiences only a short transition period before stabilizing to a new operating state based on the number of active modules. To validate performance, a comprehensive Matlab/Simulink model of the HMG and IC is developed, demonstrating robust voltage, frequency, and power regulation under various operating conditions.