Integration of Battery Energy Storage Systems (BESS) in Cold Ironing Projects: Exploring the Application of Buck-Boost Converters for Direct DC-Link Connection and Peak Smoothing

Abstract The increasing demand for sustainable port operations has accelerated the transition toward cold ironing systems as a viable alternative to conventional diesel-based ship power at berth. This thesis explores the integration of Battery Energy Storage Systems into cold ironing infrastructures, focusing on the application of buck-boost converters for direct DC-link connection, peak load smoothing, and enhanced grid reliability. Through detailed ETAP simulations, multiple operational scenarios were assessed, including variable load profiles, fault conditions, and protective selectivity. The findings reveal that BESS significantly improves system flexibility by dynamically supplying or absorbing active and reactive power, thereby mitigating voltage dips and reducing reliance on mechanical transformer tap changers. The use of bidirectional buck-boost converters enables precise DC-link voltage regulation, supporting both power quality and seamless inverter control during peak and off-peak periods. Furthermore, the thesis emphasizes the role of advanced energy dispatch strategies and selectivity coordination in fault management. Simulations demonstrate that integrated BESS not only enhances the system’s resilience to short-circuit events but also ensures selective relay operation across different fault locations especially critical in ports with complex grid topologies and motorized ship loads. By bridging simulation accuracy and real-world constraints, this research presents a comprehensive framework for future-proof, emission-reducing cold ironing systems. The outcomes contribute to the advancement of smart port electrification, aligning with global maritime decarbonization goals and setting the foundation for future integration of renewable energy sources.