Solar panels are an attractive and growing source of renewable energy in commercial and residential applications. Its use connected to the grid by means of a power converter results in a grid-connected photovoltaic system. In order to optimize this system, it is interesting to integrate several functionalities into the power converter, such as active power filtering and power factor correction. Nonlinear loads connected to the grid generate current harmonics, which deteriorates the mains power quality. Active power filters can compensate these current harmonics. A photovoltaic system with added harmonic compensation and power factor correction capabilities is proposed in this paper. A sliding mode controller is employed to control the power converter, implemented on the CompactRIO digital platform from National Instruments Corporation, allowing user friendly operation and easy tuning. The power system consists of two stages, a DC/DC boost converter and a single-phase inverter, and it is able to inject active power into the grid while compensating the current harmonics generated by nonlinear loads at the point of common coupling. The operation, design, simulation, and experimental results for the proposed system are discussed.
In many industrial fields, there is a need to design and characterize on-line and on-board hydrogen monitoring tools able to operate under extreme conditions. One of these applications is in future nuclear fusion reactors, which will use hydrogen isotopes as a plasma fuel. In this context, the measurement of the concentration of these hydrogen isotopes will be of interest to ensure the correct operating conditions for such reactors. Hydrogen sensors based on solid-state electrolytes will be the first step in the development of new analytical tools able to quantify deuterium and tritium in aggressive environments. In the present work, amperometric hydrogen sensors were constructed and evaluated using two solid-state electrolytes, BaCe0.6Zr0.3Y0.1O3-α and Sr(Ce0.9Zr0.1)0.95Yb0.05O3-α. Prototype sensors were built in order to study their sensitivity in on-line measurements. The experiments were performed in a reactor with a hydrogen-controlled environment. The sensors were evaluated at 500 and 600 °C in amperometric mode by applying 2 and 4 V voltages between electrodes. Both sensors showed increases in sensitivity when the temperature or voltage were increased.
In future fusion reactors tritium and deuterium will be used as a primary fuel. Currently, the most important research and development project about nuclear fusion energy is the ITER (International Thermonuclear Experimental Reactor). To produce the fusion reaction, tritium will be generated inside the core using a breeding blanket. One of the suggested blankets is based on the use of molten lithium – lead eutectic alloy (Pb-15.7Li) [1]. This blanket will be flowing around the reactor core and while the fusion reaction occurs, energy is released and collected with an external heat exchanger system. Due to its short half-life (12.3 years), there are not natural tritium sources. Therefore, it must be obtained in situ and continuously in the breeding blanket. This hydrogen isotope can be produced by bombarding lithium with fast neutrons, which escape from the generated and confined plasma in the toroid-shaped vacuum chamber of a tokamak, to yield tritium and helium (6Li + n → 4He + 3H + 4.8MeV) [2]. Hence, dynamic tritium concentration measurement is of major interest for nuclear fusion reaction engineering and for an experimental proof of tritium self-sufficiency in liquid metal breeding systems. Consequently, it is necessary a measuring system that allows to determine tritium concentration in high temperature conditions. Electrochemical sensors based on solid-state proton conductor ceramics can be used for that purpose. These materials have attracted significant interest because of their chemical and physical durability, especially at elevated temperatures. These electrolytes are perovskite type materials with electrical carriers, positive holes, excess electrons, oxide ion vacancies and interstitial protons, which interact with oxide ions. Under this approach, new methods of synthesis are being studied in order to obtain ceramic materials of higher quality and purity able to offer better measurement signals. In the present work, the proton conducting perovskite Sr(Ce0,9-Zr0,1)0,95Yb0,05O3-α was synthesized by two different methods. On one side, a conventional sol-gel method was employed [3]. On the other hand, the ceramic particles were synthesized by flame spray pyrolysis. Structural phases were determined by X-Ray Diffraction. The powder obtained with both methods showed a single phase of the perovskite-type and good agreement with bibliography data. Finally, the obtained ceramic materials were properly sintered and shaped in order to construct electrochemical hydrogen sensors. Amperometric measurements were performed at 500 ºC using different hydrogen partial pressures and the response of the two sensors was compared. References [1] E. Mas de les Valls, L.A. Sedano, L. Batet, I. Ricapito, A. Aiello, O. Gastaldi, F. Gabriel, Lead-lithium eutectic material database for nuclear fusion technology, J. Nucl. Mater. 376 (2008) 353–357, https://doi.org/10.1016/j.jnucmat.2008.02.016 [2] H. Mei, Q. Wu, J. Chen, B. Zhang, Y. Liu, Equivalent determination of tritium production in liquid blanket of fusion reactor using lithium isotopic abundance analysis, Fusion Eng. Des. 112 (2016) 89–92, https://doi.org/10.1016/j.fusengdes.2016.07.015 [3] E. Juhera, S. Colominas, J. Abellà, Amperometric hydrogen sensors for application in fusion reactors, Fusion Eng. Des. 124 (2017) 901–904. https://doi.org/10.1016/j.fusengdes.2017.01.049
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