Dynamic modelling of PEM Electrolyzers for power system frequency control with power HIL validation

The growing deployment of grid-connected hydrogen electrolyzer plants has established them as promising participants in frequency ancillary services due to their operational flexibility. However, the absence of accurate electrical response characteristics for electrolyzers hinders their potential for power system frequency control. In this paper, a multiphysics-based dynamic model of the proton exchange membrane (PEM) electrolyzer is developed based on the bidirectionally coupled effect between the electrochemical reaction and the bubble dynamics for power system frequency control. To accurately identify the model parameters and validate the model using frequency control, a power hardware-in-loop (HIL) platform is used that connects the digital control with the industrial PEM electrolyzer. Based on this platform, a series of model validation and system frequency control experiments are implemented. Both experimental and digital simulation results demonstrate that the proposed model has better accuracy than the existing double RC circuit model and the thermal dynamic model. Furthermore, more realistic and accurate frequency response performance of the PEM electrolyzer can be captured by the proposed model compared with the simplified RC circuit model. Finally, a MW-scale case study highlights that by adjusting the bubble dynamics, the critical trade-off between the hydrogen production economy and the frequency response performance can be modified due to the nonlinearity of frequency response characteristics.