Scaling Down Electrolysis System for Lab-Scale Test Bench: A Power Performance Perspective

With the deployment of the electrolysis system to hundreds of MW (by 2025) or even future GW scale, a down-scaled test bench with the most representative features becomes highly valuable in predicting, preventing, and analyzing system abnormalities during operation. However, such a scaled-down test bench may not be commercially available due to different technology maturity levels in power electronics. For a large-scale electrolysis system, even a test bench with a scaling down factor of 1/10 may cost millions. Technically, it remains unclear how representative a lab-scale testbench system can be to emulate MW-scale electrolysis plant operation, especially with large scaling factors at low cost. In this research, we first explored two potential methodologies for scaling down from the MW scale to a lab-scale test bench. The constant voltage approach allows us to keep four power quality performances (PQ) such as the THD, power factor, ripple factor and the cell current density constants regardless of the scaling factor. However, the electrolyzer resistance is increased with respect to the scaling factor. The constant current approach decreases the resistance with the scaling factor while maintaining the other parameters constant. Further, to mimic the behaviour of the real industrial system as closely as possible, we developed a square-root scaling approach by manipulating four parameters (voltage, current, cell area, and the scaling factor) to scale down the system while keeping five PQ performances on both AC (THD and power factor) and DC side (ripple factor, current density, and the electrolyzer resistance) constants. This theoretical analysis provided a guideline for understanding the similarity between electrolysis systems.