Design of predictive controllers for alkaline electrolyzers
Tutor / directorOcampo-Martínez, Carlos
Document typeMaster thesis
Rights accessOpen Access
Electrolyzers are systems which mission is to produce hydrogen by means of a chemical process called electrolysis. This process is capable of separating the hydrogen and oxygen molecules of the water by applying an electric current I. In that way, the hydrogen is produced in a sustainable way, since it is produced without emitting carbon dioxide into the atmosphere. In order to produce this hydrogen, there are several specifications that have to be accomplished by this high pressure alkaline electrolyzer, such as the difference between the liquid levels in both separation chambers (SCs), or the difference between the pressure of the H2 SC and the pressure of the storage tanks. The aim of this project is to develop a control strategy that achieves the desired specifications in order to increase the supplied gases purity. Since there are multiple objectives which need to be optimized in this problem, a model predictive controller (MPC) based on a multi-objective optimization problem is implemented during the development of this project. To address this problem, it is necessary to work over a control-oriented model of the electrolyzer, as well as over simulation-oriented models. These models are obtained based on several works found in the literature, with high-fidelity models previously implemented and evaluated. During the development of this project, different versions of MPCs are designed and simulated, depending on the tuning and prediction capabilities when disturbances in cur- rent and pressure are considered. The results of these MPCs are compared, as well as the differences yielded by the modification of some parameters of these MPCs. Several key performance indices (KPIs) are considered in order to compare the different versions of MPCs implemented, to facilitate the selection of the one with the best results and also in order to show the effectiveness of the proposed control approach.