Capacitor voltage balance limits in a multilevel-converter-based energy storage system

This paper studies an energy storage system based on a three-level DC-DC converter and a gridconnected neutral-point-clamped inverter. The main advantages of this multilevel power conversion system are highlighted and the neutral-point voltage oscillations are analyzed. A modulation algorithm for the DC-DC converter which includes the neutral-point voltage balance control is used to improve the voltage balancing capabilities of the inverter. Some figures are presented to show the extended operating areas without neutral-point voltage oscillations thanks to the contribution of the DC-DC converter to the voltage balance. Finally, some guidelines to size the DC-link capacitors are given for a practical application.Peer ReviewedPostprint (published version

Capacitor voltage balance limits in a multilevel-converter-based energy storage system

This paper studies an energy storage system based on a three-level DC-DC converter and a gridconnected neutral-point-clamped inverter. The main advantages of this multilevel power conversion system are highlighted and the neutral-point voltage oscillations are analyzed. A modulation algorithm for the DC-DC converter which includes the neutral-point voltage balance control is used to improve the voltage balancing capabilities of the inverter. Some figures are presented to show the extended operating areas without neutral-point voltage oscillations thanks to the contribution of the DC-DC converter to the voltage balance. Finally, some guidelines to size the DC-link capacitors are given for a practical application.Peer Reviewe

Capacitor voltage balance limits in a multilevel-converter-based energy storage system

This paper studies an energy storage system based on a three-level DC-DC converter and a gridconnected neutral-point-clamped inverter. The main advantages of this multilevel power conversion system are highlighted and the neutral-point voltage oscillations are analyzed. A modulation algorithm for the DC-DC converter which includes the neutral-point voltage balance control is used to improve the voltage balancing capabilities of the inverter. Some figures are presented to show the extended operating areas without neutral-point voltage oscillations thanks to the contribution of the DC-DC converter to the voltage balance. Finally, some guidelines to size the DC-link capacitors are given for a practical application.Peer Reviewe

Transportable hydrogen research plant based on renewable energy

Efficiency and cost are nowadays the most important barriers for the penetration of systems based on hydrogen and renewable energies. According to this background, TECNALIA Corporation has started in 2004 the HIDROTEC project: "Hydrogen Technologies for Renewable Energy Applications". The ultimate aim of this project is the implementation of a multipurpose demonstration and research plant in order to explore diverse options for sustainable energetic solutions based on hydrogen. The plant is conceived as an independent system that can be easily transported and assembled. Research and demonstration activities can thus be carried out at very different locations, including commercial renewable facilities. Modularity and scalability have also been taken into account for an optimised exploitation.Peer reviewe

Geodetic fault slip rates on active faults in the Baza sub-Basin (SE Spain): Insights for seismic hazard assessment

One of the most significant parameters for seismic hazard assessment analyses is the fault slip rate. The combination of both geological (long-term) and geodetic (short-term) data offers a more complete characterization of the seismic potential of active faults. Moreover, geodetic data are also a helpful tool for the analysis of geodynamic processes. In this work, we present the results of a local GPS network from the Baza sub-Basin (SE Spain). This network, which includes six sites, was established in 2008 and has been observed for seven years. For the first time, we obtain short-term slip rates for the two active faults in this area. For the normal Baza Fault, we estimate slip rates ranging between 0.3 ± 0.3 mm/yr and 1.3 ± 0.4 mm/yr. For the strike-slip Galera Fault, we quantify the slip rate as 0.5 ± 0.3 mm/yr. Our GPS study shows a discrepancy for the Baza Fault between the short-term slip rates and previously reported long-term rates. This discrepancy indicates that the fault could be presently in a period with a displacement rate higher than the mean of the magnitude 6 seismic cycle. Moreover, the velocity vectors that we obtained also show the regional tectonic significance of the Baza Fault, as this structure accommodates one-third of the regional extension of the Central Betic Cordillera. Our GPS-related slip rates form the basis for future seismic hazard analysis in this area. Our results have further implications, as they indicate that the Baza and Galera Faults are kinematically coherent and they divide the Baza sub-Basin into two tectonic blocks. This points to a likely physical link between the Baza and Galera Faults; hence, a potential complex rupture involving both faults should be considered in future seismic hazard assessment studies.This research was funded by the Spanish Ministry of Science, Innovation and University (Research Projects: RTI2018-100737-B-I00 and CGL2016-80687-R), the University of Alicante (Research Project: VIGROB053), the University of Jaén (PAIUJA 2019-2020 and Programa Operativo FEDER Andalucía 2014-2020 - call made by UJA 2018), the University of Granada (B-RNM-301-UGR18) and the Junta de Andalucía regional government (RNM148, RNM282, and RNM370 and P18-RT-3275 research groups)