HVDC Systems and Renewable Energy in a Comparative Study of Technologies and Applications

• Comprehensive comparative analysis of HVDC and HVAC transmission systems for renewable energy integration. • Techno-economic evaluation showing HVDC reduces losses by up to 50% beyond 400 km and submarine routes. • Original benchmarking of converter topologies (LCC, MMC, CHB, hybrid) with performance metrics and innovation pathways. • Real-world validation with case studies including HelWin1 and IceLink projects, proving HVDC feasibility. • Future directions discussed: wide-bandgap semiconductors, AI-driven controls, and multi-terminal HVDC grids. This paper presents a comprehensive comparative analysis of High Voltage Direct Current (HVDC) and High Voltage Alternating Current (HVAC) transmission systems for integrating large-scale offshore wind energy into modern power grids. The study delivers a detailed techno-economic evaluation, assessing critical parameters such as transmission efficiency, power losses, electromagnetic compatibility, grid stability, and lifetime costs. It further provides an original benchmarking of HVDC converter topologies—including Line Commutated Converters (LCC), Modular Multilevel Converters (MMC), and Cascaded H-Bridge (CHB) converters—quantifying their performance in weak grids, fault resilience, and efficiency. The analysis confirms that for distances exceeding 80-100 km, HVDC systems, particularly those utilizing VSC-based technologies like MMC, offer superior efficiency with losses of 1.5–2% per 100 km compared to 3–4% for HVAC, alongside lower lifetime costs and enhanced controllability. The work also explores advanced intelligent protection schemes using artificial intelligence and addresses key challenges such as electromagnetic interference (EMI) in urban integration. The findings underscore HVDC's pivotal role as an enabling technology for the sustainable and reliable transmission of renewable energy over long distances.