Description

Due to the current climate crisis, significant efforts are being made in the field of renewable energies, being one of the main challenges the storage of energy in an efficient, environmentally friendly and low-cost way.

One of the solutions that has aroused the most attraction in recent years are redox flow batteries, standing out for their flexible design in terms of power and energy, among many other advantages. In particular, vanadium redox flow batteries hold the most promise, due to their long lifetime. However, in view of its recent boom, there are still important challenges to be resolved, such as the correct estimation of the state of charge and the state of health or the search for better materials, among other important aspects.

Specifically, this work focuses on the modeling and control aspects of vanadium redox flow batteries, fields that are still being studied by the scientific community, in need of finding adequate control laws, as well as state and parameter estimators.

The first part of this work focuses on presenting the operation and characteristics of vanadium redox flow batteries, as well as developing a state of the art in terms of modeling and control. The second part presents the mathematical development of a model that takes into account the most important aspects and variables of vanadium batteries, under different chemical and physical scenarios. The developed generic model is presented as a tool for anyone interested in understanding the most important dynamics of these electrochemical devices, providing a free-to-use interface in the Matlab environment. In addition, at the end of this section the different conservation principles are presented that allow reducing the order of the model and, therefore, its complexity for the control part. The following chapters present the development of the state and parameter estimators, considering the different models. The main objective is to present new and different control techniques that allow estimating the state of charge and the state of health of the system, without considering some hypotheses that are commonly used by the scientific community. Continuing with this part, the different control strategies that existed are presented, formulating different controllers that allow the system to operate safely, efficiently and optimally. Finally, the experimental platform that has been designed to validate the different studies carried out and the results obtained from this experimental prototype is shown.