@article {232, title = {Global stabilisation of continuous bioreactors: Tools for analysis and design of feeding laws}, journal = {Automatica}, volume = {89}, year = {2018}, pages = {340 - 348}, abstract = {

This work revisits the dynamic behaviour of stirred continuous reactors in which a single bioreaction with unknown kinetics occurs. Conditions on the feeding strategy to avoid washing out the biomass and falling in batch operation are obtained. These conditions derive in a closed positively invariant region including the desired operating point. It is stated that no closed orbits may exist in this region and, furthermore, that no fixed point exists but on one of its borders. Therefore, global stability is achieved by finding a feeding law that fulfils the aforementioned invariant conditions and gives a single equilibrium for a first-order dynamics. These results are useful to determine the stability properties of different control laws and, more importantly, to design new ones. The main advantages of the proposed approach are its simplicity and that, differing from previous results, input saturation does not affect stability results. The potentiality of the developed tools is illustrated by means of classical and novel feeding laws.

}, keywords = {Bioprocess control, Invariant control, Nonlinear control}, issn = {0005-1098}, doi = {https://doi.org/10.1016/j.automatica.2017.12.041}, author = {De Battista, Hern{\'a}n and Jamilis, Mart{\'\i}n and Garelli, Fabricio and Pic{\'o}, Jes{\'u}s} } @article {123, title = {Control of a Supercapacitor Energy Storage System for Microgrid Applications}, journal = {Energy Conversion, IEEE Transactions on}, volume = {28}, year = {2013}, month = {Sept}, pages = {690-697}, abstract = {

The proper operation of a microgrid requires storage devices that increase the inertia and avoid instability of the system. This paper presents the control of an energy storage system (ESS) based on supercapacitor in the context of grid-connected microgrids. The ESS is composed of AC/DC and DC/DC converters tied by a dc link. A single sliding mode strategy is proposed to control a bidirectional dc/dc converter, capable of working properly under all operating conditions. The switching devices are commanded by a single sliding function, dynamically shaped by references sent from the microgrid central controller. This feature facilitates the implementation and design of the control law and simplifies the stability analysis over the entire operating range. The effectiveness of the proposed control strategy is illustrated by experimental results.

}, keywords = {AC-DC converter, AC-DC power convertors, bidirectional DC-DC converter control, DC-DC power convertors, distributed power generation, Energy storage systems (ESS), ESS, experimental setup, grid connected microgrid application, microgrid central controller, microgrids, Nonlinear control, Power electronics, power generation control, power grids, power system interconnection, sliding function, Sliding mode control, sliding mode strategy, stability, stability analysis, supercapacitor energy storage system control, supercapacitors, switching convertors, switching device, variable structure systems}, issn = {0885-8969}, doi = {10.1109/TEC.2013.2260752}, author = {Inthamoussou, Fernando A. and Pegueroles-Queralt, Jordi and Bianchi, Fernando D.} } @article {28, title = {Globally stabilizing control of fed-batch processes with Haldane kinetics using growth rate estimation feedback}, journal = {Journal of Process Control}, volume = {16}, year = {2006}, pages = {865 - 875}, abstract = {

The regulation of the biomass specific growth rate is an important goal in many biotechnological applications. To achieve this goal in fed-batch processes, several control strategies have been developed employing a closed loop version of the exponential feeding law, an estimation of the controlled variable and some error feedback term. In the case of non-monotonic kinetics, the specified growth rate can be achieved at two different substrate concentration values. Because of the inherent unstable properties of the system in the decreasing portion of the kinetics function, stabilization becomes a crucial problem in this high-substrate operating region. In this context, the dynamic behavior of fed-batch processes with Haldane kinetics is further investigated. In particular, some conditions for global stability and performance improvement are derived. Then, a stabilizing control law based on a partial state feedback with gain dependent on the output error feedback and gain saturation is proposed. Although particular emphasis is put on the critical case of high-substrate operation, low-substrate regulation is also treated.

}, keywords = {Nonlinear control}, issn = {0959-1524}, doi = {10.1016/j.jprocont.2006.02.001}, url = {http://www.sciencedirect.com/science/article/pii/S0959152406000229}, author = {De Battista, Hern{\'a}n and Pic{\'o}, Jes{\'u}s and Pic{\'o}-Marco, Enric} }