Comparison of Low-Frequency Transformer-Based and Solid-State Transformer-Based Systems for High-Power Electrolyzer Power Supply

Green hydrogen production through water electrolysis is emerging as a key technology in the global energy transition. As electrolyzer capacities scale up, the design of their power supply systems becomes critical to ensure efficiency, reliability, and cost-effectiveness. Traditionally, low-frequency transformer (LFT)-based architectures have been employed for grid connection and galvanic isolation. However, solid-state transformer (SST)-based solutions are gaining attention due to their potential for high efficiency, modularity, and advanced control features. This paper presents a comprehensive comparison between LFT-based and SST-based power supply systems for high-power electrolyzer applications. Both systems are rated at 1.5 MVA and designed to interface with a 10 kV distribution grid. The comparison considers component requirements, power density, and overall system efficiency. Simulation and theoretical results are provided, highlighting the trade-offs between the two architectures. The SST-based solution achieves superior performance, with an efficiency of 98.5% compared to 97% for the LFT-based counterpart, and a significantly reduced volume of 420 dm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> versus 1473 dm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>.