Solar Power and Energy Storage Systems

Today’s energy path depends largely on fossil fuels, and we are already facing alarming consequences in terms of climate change and energy security. Solar cells have been recognized as an important alternative power source since the 1970s. Solar cells are also promising as a carbon-free energy source that can suppress global warming. The power conversion efficiency of a solar cell is well defined as the ratio between the electric power produced by the solar cell and the incident sunlight energy per unit of time. At present the highest reported cell efficiencies in laboratories are around 40%, while the power conversion efficiencies for thermal power generation can exceed 50%. This, however, by no means indicates any advantage related to thermal generation, since its resources, such as fossil fuels, are limited while solar energy is fundamentally unlimited. However, during nighttimes, we cannot get electricity from the sun, so we need some storage systems for nighttimes. Design and fabrication of electrochemical energy storage systems with both high energy and power densities as well as long cycling life is of great importance. As one of these systems, a batterysupercapacitor hybrid device (BSH) is typically constructed with a high-capacity battery-type electrode and a high-rate capacitive electrode, which has attracted enormous attention due to its potential applications in, for example, future electric vehicles, smart electric grids, and even miniaturized electronic/optoelectronic devices. Before we start research on BSH, we must study super-capacitors. So author has introduced the results of several superconductor studies in Chapters 5 and 6. In this book author has introduced several examples of solar energy applications, such as solar ships, DAB converters, an

Development of A New Coating System for The High Functional Mold in Thin-wall Casting

A new inorganic binder system has been developed to prepare the mold having a high strength for the thin-walled casting. To increase the fracture strength at high temperature, a large amount of inorganic binder should be converted into glass phase and the generated glass phase has to be homogeneously coated on the surface of starting particles. In this work, two types of process were employed to investigate the coating and glassification efficiencies of inorganic precursor. In the first process (process I), the green body consisting of starting powder and organic binder was dipped in the inorganic precursor solution. In the second process (process II), the starting powder was coated by inorganic precursor, and then the organic binder was used to form the green body. The mold sample prepared using process II showed the higher strength value than that using process I, owing to the inclement effect on the glassfication efficiency by the loss of inorganic precursor in process I. The prepared real mold was perfectly produced and the casted product showed a clean surface without defects such as dross, nonmetallic inclusions, and crack. Consequently, the new inorganic binder system could be applied for preparing the mold for the thin-wall casting having high mechanical properties

Autonomous Control Strategy of DC Microgrid for Islanding mode using Power Line Communication

This paper proposes a DC-bus signaling (DBS) method for autonomous power management in a DC microgrid, used to improve its reliability. Centralized power management systems require communication between the power sources and loads. However, the DBS method operates based on the common DC-bus voltage and does not require communication. Based on the DC-bus voltage band, the DC-bus voltage can be used to inform the status of the DC-bus in various scenarios. The DC microgrid operates independently to maintain the system stably in the DC-bus voltage band. The DC microgrid can be divided into a grid-connected mode and an islanding mode. This paper proposes a control strategy based on power management of various independent components in islanding mode. In addition, the autonomous control method for switching the converter???s operation between grid-connected mode and islanding mode is proposed. A DC microgrid test bed consisting of a grid-connected AC/DC converter, a bidirectional DC/DC converter, a renewable energy simulator, DC home appliances and a DC-bus protector is used to test the proposed control strategy. The proposed autonomous control strategy is experimentally verified using the DC microgrid test bed