Induction Heating Consolidation of TiO2 Sol-Gel Coating on Stainless Steel Support for Photocatalysis Applications

A high-frequency induction heater was used to sinter titanium dioxide thin film on stainless steel plates with the aim of being used as photo-electrodes in wastewaters treatment. To validate the use of this sintering technique, the electrodes were prepared using sol-gel and dip-coating, followed by two different annealing processes for comparison: a conventional furnace and a high-frequency induction heating. To characterize the electrodes, X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical and photocatalysis tests were performed. Anatase and rutile phases were obtained for both annealing techniques. A more regular surface morphology was achieved via the induction heating (IH) treatment at 300 ºC. The impedance study showed a lower resistance of IH samples, representing an improvement in the charge carrier separation and its fast transfer to the surface of the electrode. The photo-oxidation of methylene blue exhibited a higher degradation compared with the conventional furnace samples prepared in this study

LA COMUNIDAD LITERARIA EN LAS TUNAS DESDE 1990 A 2000. APORTES AL DESARROLLO CULTURAL DE LA PROVINCIA

Las Tunas is inserted in the literature with the work of the Napoles Fajardo brothers: Juan Cristobal, El Cucalambé, and Manuel, Sanlope, author of Flores del alma (1860), first book published in the locality. Since then several names and significant events are recorded in the literary work. This study aims to assess the contributions offered by the literary community of Las Tunas cultural development, from 1990 to 2000; stage in which the conditions for establishment and consolidation are propitiated. For that, includes the main contributions of the literary community of Las Tunas in that period, which includes among its members the publishing Sanlope, activities and competitions literary, institutional relations and most significant authors. These corroborate the existence of it and make it possible to assess how, from her remarkable contributions that put the province in the history of Cuban culture and literature are made.Las Tunas se inserta en la literatura con la obra de los hermanos Nápoles Fajardo: Juan Cristóbal, El Cucalambé, y Manuel, Sanlope, autor de Flores del alma (1860), primer libro publicado en la localidad. A partir de entonces varios nombres y hechos significativos se inscriben en el quehacer literario. El presente artículo tiene como objetivo valorar los aportes que brinda la comunidad literaria de Las Tunas al desarrollo cultural, desde 1990 a 2000; etapa en la que se propician las condiciones para su establecimiento y consolidación. Para ello recoge las principales contribuciones de la comunidad literaria de Las Tunas en ese período, la cual incluye entre sus componentes a la editorial Sanlope, actividades y concursos literarios, relaciones interinstitucionales y autores más significativos. Estos corroboran la existencia de la misma y posibilitan valorar cómo, desde ella, se logra situar a la provincia en la historia de la cultura y la literatura cubanas

A series hybrid “real inertia” energy storage system

The wide scale market penetration of numerous renewable energy technologies is dependent, at least in part, on developing reliable energy storage methods that can alleviate concerns over potentially interrupted and uncertain supplies. Many challenges need to be overcome, not least among them is allowing capacity for the wide range of time scales required to ensure grid stability. In thermal power plant, high frequency/short duration demand fluctuations, acting at the milliseconds to several seconds time scale, are addressed passively by the inertia of the grid. Here, grid inertia can be thought of as the mechanical inertia of spinning steel in steam and gas turbines. This allows time for active control measures to take effect at the tens of second to hours time scale and for the system to recover without a supply frequency deviation that is noticeable to the customer. It is of paramount importance that, as thermal plant is retired, renewable energy generation and storage systems account for the loss of this inertia. In the literature, strategies to address the loss of “real” inertia have often relied on emulation rather than actual replacement. The present work focuses on the preliminary development of a novel energy storage system that makes use of real inertia to address short term supply/demand imbalances while simultaneously allowing for extended depths of discharge. The concept looks to combine flywheel and compressed fluid energy stores in order to power a synchronous generator. By combining these energy storage technologies through a differential drive unit, DDU, it is anticipated that the benefits of high system inertia can be exploited in the short term while allowing energy to be continually extracted from the flywheel in the long term during storage discharge. The use of a DDU makes the present design particularly novel and distinct from other hybrid systems. In essence, this inclusion allows energy to be extracted entirely from the flywheel, inducing “real” inertia, or entirely from the secondary store, inducing “synthetic” inertia, or some combination of the two. Fundamental sizing calculations for a 50MW system with 20MWh of storage capacity are presented and used to design a suitable control system that allows for the operation of both primary flywheel and secondary compressed fluid energy stores. The transient behaviour of the system is simulated for several charge/discharge time profiles to demonstrate response stability for the system. Comments on system turnaround efficiency, which is dependent upon loading history but for the intended applications can be considered to be greater than 90% are also made here, along with a case study application to an isolated Californian solar powered grid

Are we seeing clearly? The need for aligned vision and supporting strategies to deliver net-zero electricity systems

This paper explores the trends, step changes and innovations that could impact the integration of renewable energy into electricity systems, explores interventions that may be required, and identifies key areas for policy makers to consider. A Delphi approach is used to collect, synthesise, and seek consensus across expert viewpoints. Over sixty experts across a range of geographies including the US, Europe, New-Zealand, Australia, Africa, India and China participated. They identified 26 trends, 20 step changes, and 26 innovations that could lead to major shifts in the design, operation, or management of electricity systems. Findings suggest that key challenges are not technological. Instead they are with delivering an aligned vision, supported by institutional structures, to incentivise, facilitate, and de-risk the delivery of a completely different type of energy system. There is a clear role for government and policy to provide a future energy vision and steer on strategic issues to deliver it; to create space for new actors and business models aligned with this vision; and to create an environment where research, development, demonstration and deployment can promote technologies, system integration and business model innovation at a rate commensurate with delivering net-zero electricity system

Application of Meta-Heuristic Techniques for Optimal Load Shedding in Islanded Distribution Network with High Penetration of Solar PV Generation

Recently, several environmental problems are beginning to affect all aspects of life. For this reason, many governments and international agencies have expressed great interest in using more renewable energy sources (RESs). However, integrating more RESs with distribution networks resulted in several critical problems vis-à-vis the frequency stability, which might lead to a complete blackout if not properly treated. Therefore, this paper proposed a new Under Frequency Load Shedding (UFLS) scheme for islanding distribution network. This scheme uses three meta-heuristics techniques, binary evolutionary programming (BEP), Binary genetic algorithm (BGA), and Binary particle swarm optimization (BPSO), to determine the optimal combination of loads that needs to be shed from the islanded distribution network. Compared with existing UFLS schemes using fixed priority loads, the proposed scheme has the ability to restore the network frequency without any overshooting. Furthermore, in terms of execution time, the simulation results show that the BEP technique is fast enough to shed the optimal combination of loads compared with BGA and BPSO techniques

Frequency control scheme for islanded distribution network with high PV penetration / Mohammad Hussein Mohammad Dreidy

Air pollution due to fossil fuel power plants are causing serious environmental problems, which affect all aspects of life. Due to this, many governments and power utility companies are expressing great interest in Renewable Energy Sources (RESs). Generally, using RESs in a distribution system such as solar Photovoltaic (PV) decreases dependence on fossil fuel. However, at high PV penetration levels, an islanded distribution network suffers from critical frequency stability issues. This occurs due to two main reasons: first, the reduction of the distribution network inertia with high PV penetration, where in this condition, the rate of change of frequency (ROCOF) will be high enough to activate the load shedding controller, even for small power disturbance, and second, this type of networks has a small spinning reserve, where the PV generations are normally providing the maximum output power. The main aim of this research is to develop a comprehensive frequency control scheme for islanding distribution networks with high PV penetration. This scheme is used to stabilize the frequency of the network to a value that is suitable for the islanded and reconnection processes. To achieve this aim, three different controllers were proposed in this scheme; inertia, frequency regulation, and under-frequency load shedding (UFLS) controllers. The inertia controller is designed for PV generation to reduce the network frequency deviation, which is initiated immediately during disturbance event. After a few seconds, a frequency regulation controller, which consists of primary and secondary frequency controllers, is activated. This frequency regulation controller was proposed to provide sufficient power from the Battery Storage System (BSS) to stabilize the frequency within a few minutes. When inertia and frequency regulation controllers fail to stop the frequency deviation, an optimal (UFLS) controller is initiated from Centralized Control System (CCS) to shed the required loads. On top of shedding loads, the CCS is used to manage the operation of frequency control scheme and reconnect the grid. The proposed frequency control scheme and centralized control system were tested using a part of Malaysia’s distribution network (29-bus). The distribution network was modeled and simulated for different PV penetration levels using PSCAD//EMTDC software. The simulation results confirmed that the proposed scheme is able to stabilize the frequency of an islanded distribution network, with 50% PV penetration. This scheme is also capable of recovering the network frequency for small load and radiation changes just before it reaches the load shedding limit (49.5 Hz). Furthermore, at high PV penetration and large disturbance events, the proposed scheme can still recover the frequency by shedding the required loads within (0.254 seconds) without overshooting the frequency. Moreover, when the proposed frequency control scheme is coordinated with CCS, the islanded distribution network will be smoothly reconnected to the main grid. Therefore, this frequency control scheme has potential to be applied in real distribution networks with high PV penetration

Application of Meta-Heuristic Techniques for Optimal Load Shedding in Islanded Distribution Network with High Penetration of Solar PV Generation

Recently, several environmental problems are beginning to affect all aspects of life. For this reason, many governments and international agencies have expressed great interest in using more renewable energy sources (RESs). However, integrating more RESs with distribution networks resulted in several critical problems vis-à-vis the frequency stability, which might lead to a complete blackout if not properly treated. Therefore, this paper proposed a new Under Frequency Load Shedding (UFLS) scheme for islanding distribution network. This scheme uses three meta-heuristics techniques, binary evolutionary programming (BEP), Binary genetic algorithm (BGA), and Binary particle swarm optimization (BPSO), to determine the optimal combination of loads that needs to be shed from the islanded distribution network. Compared with existing UFLS schemes using fixed priority loads, the proposed scheme has the ability to restore the network frequency without any overshooting. Furthermore, in terms of execution time, the simulation results show that the BEP technique is fast enough to shed the optimal combination of loads compared with BGA and BPSO techniques

La comunidad literaria en Las Tunas desde 1990 a 2000. Aportes al desarrollo cultural de la provincia.

Las Tunas is inserted in the literature with the work of the Napoles Fajardo brothers: Juan Cristobal, El Cucalambé, and Manuel, Sanlope, author of Flores del alma (1860), first book published in the locality. Since then several names and significant events are recorded in the literary work. This study aims to assess the contributions offered by the literary community of Las Tunas cultural development, from 1990 to 2000; stage in which the conditions for establishment and consolidation are propitiated. For that, includes the main contributions of the literary community of Las Tunas in that period, which includes among its members the publishing Sanlope, activities and competitions literary, institutional relations and most significant authors. These corroborate the existence of it and make it possible to assess how, from her remarkable contributions that put the province in the history of Cuban culture and literature are made.Las Tunas se inserta en la literatura con la obra de los hermanos Nápoles Fajardo: Juan Cristóbal, El Cucalambé, y Manuel, Sanlope, autor de Flores del alma (1860), primer libro publicado en la localidad. A partir de entonces varios nombres y hechos significativos se inscriben en el quehacer literario. El presente artículo tiene como objetivo valorar los aportes que brinda la comunidad literaria de Las Tunas al desarrollo cultural, desde 1990 a 2000; etapa en la que se propician las condiciones para su establecimiento y consolidación. Para ello recoge las principales contribuciones de la comunidad literaria de Las Tunas en ese período, la cual incluye entre sus componentes a la editorial Sanlope, actividades y concursos literarios, relaciones interinstitucionales y autores más significativos. Estos corroboran la existencia de la misma y posibilitan valorar cómo, desde ella, se logra situar a la provincia en la historia de la cultura y la literatura cubanas