BUSCADOR RECOLECTA

This paper reports on the electro-thermal modelling of a Maxwell supercapacitor (SC), model BMOD0083
with a rated capacitance of 83 F and rated voltage of 48 V. One electrical equivalent circuit was used to
model the electrical behaviour whilst another served to simulate the thermal behaviour. The models
were designed to predict the SC operating voltage and temperature, by taking the electric current and
ambient temperature as input variables. A five-stage iterative method, applied to three experiments,
served to obtain the parameter values for each model. The models were implemented in MATLABSimulink , where they interacted to reciprocally provide information. These models were then validated
through a number of tests, subjecting the SC to different current and frequency profiles. These tests
included the validation of a bank of supercapacitors integrated into an electric microgrid, in a real
operating environment. Satisfactory results were obtained from the electric and thermal models, with
RMSE values of less than 0.65 V in all validations., Spanish Ministry of Economy and Competitiveness under grant DPI2010-21671-C02-01 and the Government of Navarre and FEDER funds under project “Microgrids in Navarra: design and implementation”.

In the last quarter of a century, high-frequency
(HF) transformer design has been one of the major concerns to power electronics designers in order to increase
converter power densities and efficiencies. Conventional
design methodologies are based on iterative processes
and rules of thumb founded more on expertise than on
theoretical developments. This paper presents an analytical design methodology for litz-wired HF power transformers that provides a deep insight into the transformer
design problem making it a powerful tool for converter
designers. The most suitable models for the calculation
of core and winding losses and the transformer thermal
resistance are first selected and then validated with a
5-kW 50-kHz commercial transformer for a photovoltaic
application. Based on these models, the design methodology is finally proposed, reducing the design issue to
directly solve a five-variable nonlinear optimization problem. The methodology is illustrated with a detailed design in terms of magnetic material, core geometry, and
primary and secondary litz-wire sizing. The optimal design
achieves a 46.5% power density increase and a higher
efficiency of 99.70% when compared with the commercial one., This work was supported in part by the Spanish Ministry of Economy and Competitiveness under Grant DPI2010-21671-C02-01 and Grant DPI2013-42853-R, in part by the
Public University of Navarra, and in part by Ingeteam Power Technology.

This paper reports on the modelling of a commercial 1.2 kW proton exchange membrane fuel cell (PEMFC), based on interrelated electrical and thermal models. The electrical model proposed is based on the integration of the thermodynamic and electrochemical phenomena taking place in the FC whilst the thermal model is established from the FC thermal energy balance. The combination of both models makes it possible to predict the FC voltage, based on the current demanded and the ambient temperature. Furthermore, an experimental characterization is conducted and the parameters for the models associated with the FC electrical and thermal performance are obtained. The models are implemented in Matlab Simulink and validated in a number of operating environments, for steady-state and dynamic modes alike. In turn, the FC models are validated in an actual microgrid operating environment, through the series connection of 4 PEMFC. The simulations of the models precisely and accurately reproduce the FC electrical and thermal performance., The authors acknowledge the Spanish Ministry of Economy and Competitiveness under grant DPI2010-21671-C02-01 and the Government of Navarre and FEDER funds under project “Microgrids in Navarra: design and implementation”.

This paper proposes an energy management strategy for a residential electrothermal microgrid, based on renewable energy sources. While grid connected, it makes use of a hybrid electrothermal storage system, formed by a battery and a hot water tank along with an electrical water heater as a controllable load, which make possible the energy management within the microgrid. The microgrid emulates the operation of a single family home with domestic hot water (DHW) consumption, a heating, ventilation and air conditioning (HVAC) system as well as the typical electric loads. An energy management strategy has been designed which optimizes the power exchanged with the grid profile in terms of peaks and fluctuations, in applications with high penetration levels of renewables. The proposed energy management strategy has been evaluated and validated experimentally in a full scale residential microgrid built in our Renewable Energy Laboratory, by means of continuous operation under real conditions. The results show that the combination of electric and thermal storage systems with controllable loads is a promising technology that could maximize the penetration level of renewable energies in the electric system., This work was partially funded by the Government of Navarra and the FEDER funds under project
“Microgrids in Navarra: design, development and implementation” and by the Spanish Ministry of
Economy and Competitiveness under grant DPI2010-21671-C02-01, as well as by the European Union
under the project FP7-308468, “PVCROPS-Photovoltaic Cost reduction, reliability, operational
performance, prediction and simulation”.

This paper reviews water electrolysis technologies for hydrogen production and also surveys the state of the art of water electrolysis integration with renewable energies. First, attention is paid to the thermodynamic and electrochemical processes to better understand how electrolysis cells work and how they can be combined to build big electrolysis modules. The electrolysis process and the characteristics, advantages, drawbacks, and challenges of the three main existing electrolysis technologies, namely alkaline, polymer electrolyte membrane, and solid oxide electrolyte, are then discussed. Current manufacturers and the main features of commercially available electrolyzers are extensively reviewed. Finally, the possible configurations allowing the integration of water electrolysis units with renewable energy sources in both autonomous and grid-connected systems are presented and some relevant demonstration projects are commented., This work was supported by the Spanish Ministry of Science and Innovation under Grants DPI2010-21671-C02-01 and ENE2009-14522-C05-03