Modelling and control of LV multiport converters

The EU’s commitment to net-zero greenhouse gas emissions by 2050 necessitates rapid deployment of power converter-interfaced devices in electric power systems. This includes renewable energy sources (RESs) and energy storage systems (ESSs) in distribution networks (DNs). Traditional two-port power converters often fail to meet demand profiles effectively, leading to significant voltage fluctuations during generation-demand imbalances, particularly in radial feeders. Multiport Converters (MPCs) provide an effective solution by integrating multiple energy ports into a single aggregated hub, offering high controllability and efficient energy management across all ports while maintaining power quality and grid stability. MPCs can address DN challenges by reducing conversion stages, leading to cost-efficiency and higher power density. MPCs offer flexibility in selecting the number of ports and their characteristics (AC or DC), making them ideal energy hubs for connecting feeders, substations, RESs, and ESSs. Compared to conventional systems composed of multiple individual interfacing converters, MPCs provide lower system cost, reduced size, and higher power density. Advanced controllability, communication, and computational capabilities in MPCs support future smart grids by decentralizing decision-making processes, enabling rapid responses, and holistic control to enhance overall grid performance. WP3 focuses on investigating and enabling MPCs in low-voltage (LV) DNs, addressing challenges such as developing efficient and compact circuit topologies for interfacing three-phase and single-phase AC systems with multiple DC ports. This will enhance converter efficiency, improve power density, and reduce component counts by minimizing conversion stages. Additionally, control and modulation constraints will be addressed to ensure Zero-Voltage-Switching (ZVS) and reduce passive reactive elements to boost power density. High-performance current and voltage control techniques will maintain control bandwidth and impedance passivity across all ports for frequency intervals of interest, reducing dynamic instability and transient oscillations in future distribution grids. At the distribution level, DNs with significant penetration of renewable sources and various industrial loads require power electronics to facilitate the integration of renewables and ESSs, optimize network use, and connect loads at different voltage levels. Powerelectronic solutions like ESOP, smart transformers, and MPCs enhance capacity, flexibility, and controllability in distribution grids. For residential areas, MPCs accommodate future connections of EVs and distributed renewable generation, improving load balance, voltages, and renewable capacity. In household settings, MPCs link local RESs and ESSs with the distribution grid, supporting local energy storage systems and EVs. This enhances system efficiency and reduces integration costs, optimizing energy management at the household level and contributing to the overall stability and efficiency of the distribution network. This report, Deliverable 3.1 of the iPLUG project, overviews the work carried out within WP3 research activities on MPCs for LV applications. Key contributions include identifying research challenges for SOP converters and propose, introducing a passivity-oriented controller design framework for robust stability, proposing novel single-stage non-isolated MPCs for residential applications, and enhancing dynamic performance with non-linear control of the Y-converter.