Electrolyzer Degradation-Power Electronics One -Way Interaction Model

Abstract

The water electrolysis process requires a high DC current supply that can sustain the desired hydrogen production rate over a large period of operation at a competitive cost. During the conversion of electricity from AC to DC, power quality may be affected because of the non-linear effect caused by the power electronics. Most of the recent research has focused on exploring different rectifier topologies. None of them have investigated the influence of cell stack degradation on the performance of power electronics. In this work, we built a one-way interaction model to predict the influence of electrolyzer degradation on power electronics output over multiscale operational time (from milliseconds to years) for proton exchange membrane electrolyzer (PEM). In this model, we assume a constant degradation rate on the electrolyzer that results in a linear increase of internal resistance over time. Counterintuitively, rather than the power quality decreasing, results show that the power quality increased with the electrolyzer degradation for both the AC (power factor and THD) and DC side (ripple) for the 6-pulse thyristor. Furthermore, the influence of three variables (degradation rate, load current, and topology) on AC (power factor and THD) and DC (ripple factor) side power output were investigated. Finally, results were partially validated with experimental data from a 20 MW scale PEM electrolyzer.