Effective suppression for overshoot voltage of PEM electrolyzer by power supply

Abstract

Renewable energy generation which inherently has intermittent and fluctuating characteristics, makes Proton Exchange Membrane (PEM) electrolyzers operate intermittently. Specially, the overshoot voltage phenomenon will be happened when the electrolyzer power increase rapidly to stable operate. This can cause the electrolyzer to operate overload, which reduce hydrogen production efficiency, increase power supply capacity and reduce its reliability. In this work, for suppressing overshoot voltage and protecting electrolyzer, the electrolyzer voltage is controlled through the power supply outputs a DC-biased voltage with a sine waveform. Comparing with the traditional protection scheme, the overshoot voltage is reduced by 17.5 % ∼ 30.5 % during low power operation. Noteworthily, the overshoot voltage is disappeared completely and the polarization voltage can be reduced by 7.6 % ∼ 13.5 % when the electrolyzer is in high power operation. Furthermore, the anode catalyst layer is characterized by the advanced characterization such as scanning electron microscopes (SEM), X-ray diffractometers (XRD), and micro-CT. It is found that the micrometer-scale pore collapse and the ion leaching will be suppressed by regulating electrolyzer voltage. Finally, through COMSOL Multiphysics simulations confirm that the reduction of pore diameter will increase the electrolyzer internal resistance and current distribution inhomogeneity which have a significant impact on the overshoot voltage behavior. Consequently, the research results provide a theoretical basis for designing a new generation of power supply-side electrolyzer protection schemes and membrane electrode.