Electrical Engineering

Lack of quality electricity supply in the remote areas is one of the main hindering factors of global development. Many countries around the world are trying to utilize renewable energy sources for remote electrification including developing countries like Bangladesh. After the renowned Solar Home System (SHS) program, Bangladesh is now focusing on solar PVdiesel hybrid minigrid system to reach more people by providing affordable electricity. Following the availability of electricity in the form of minigrid, a development in industries like sawmills, grinding mills, husking mills is predictable. Therefore, daytime loads might have significant contribution in energy consumption, unlike the usual residential scenario. With this, the irrigation demands are there during the dry season. This study analyzes the techno-economic feasibility of the solar PV-diesel hybrid system with different load conditions. A remote area of southern Bangladesh is taken as the case site. Three case studies are formulated based on the time of using irrigation pumps. HOMER Pro Microgrid Analysis Tool has been used to find the most optimized configuration for each case study. The optimized configurations from each case study are then evaluated based on the cost of electricity (COE), greenhouse gas emissions and renewable energy fraction. The generation profile of solar PV and diesel generators are analyzed for each case study. From the techno-economic evaluation, it is observed that the optimum time to run the irrigation pumps is during the daytime. In this case, the solar PV has the highest contribution to meet the energy demand with the slightly increased cost of electricity.

"This paper compares the features of second generation (2G) High Temperature Superconducting (HTS) field coil with those of magnesium diboride (MgB2) field coil for a 10 MW class superconducting generator. Both coils can function effectively in their respective magnetic flux density range: 10-12 T for 2G HTS field coil, 2 T for MgB2 superconducting field coil. Even though some leading researchers have been developing 10 MW class superconducting generator with 2G HTS field coil, other research groups have begun to focus on MgB2 wire, which is more economical and suitable for mass production. However 2G HTS wire is still appealing in functions such as in-field property and critical temperature, it shows higher in-field property and critical temperature than MgB2 wire."

"High-temperature superconducting (HTS) rotating machines always require an electric current of from several hundreds to several thousand amperes to be led from outside into cold region of the field coil. Heat losses through the current leads then assume tremendous importance. Consequently, it is necessary to acquire optimal design for the leads which would achieve minimum heat loss during operation of machines for a given electrical current. In this paper, conduction cooled current lead type of 10 MW-Class HTS rotating machine will be chosen, a conceptual design will be discussed and performed relied on the least heat lost estimation between conventional metal lead and partially HTS lead. In addition, steady-state thermal characteristic of each one also is considered and illustrated."

"In this paper, the  general  electromagnetic design process  of a 10-MW-class high-temperature superconducting (HTS) synchronous generator that is intended to be utilized for large scale offshore wind generator is discussed. This paper presents three-dimensional (3D) electromagnetic design proposal and electrical characteristic analysis results of a 10-MW-class HTS synchronous generator for wind power. For more detailed design by reducing the errors of a two-dimensional (2D) design owing to leakage flux in air-gap, we redesign and analyze the 2D conceptual electromagnetic design model of the HTS synchronous generator using 3D finite element analysis(FEA) software. Then electrical characteristics which include the no-load and full-load voltage of generator, harmonic contents of these two load conditions, voltage regulation and losses of generator are analyzed by commercial 3D FEA software."

This paper presents an analysis of the mechanical characteristics of a 17-MW-class high-temperature superconducting (HTS) synchronous motor. The fundamental electromagnetic, structural, and thermal design must be accompanied to maintain the reliability of an HTS rotating machine when designing an HTS synchronous motor with an HTS wire with a high current density instead of a copper wire used in a conventional rotating machine. Therefore, we analyze the structural characteristics from two perspectives using three-dimensional (3D) finite-element analysis for the structural design of a 17-MW-class HTS synchronous motor that is intended to be utilized for ships with electric propulsion.

Superconducting field coils consist of race-track-type double pancake (DP) coil modules fabricated using high-temperature superconducting (HTS) wire with high current density and zero resistance. The structural shape of race-track-type DP coils strongly influences the intensity and the shape of the magnetic flux density in the air-gap, which determines the generator electrical output and the superconducting field coil performance. Hence, the structural shape of a superconducting field coil is very important in designing a large-scale superconducting generator. We analyze the characteristics of a 10-MW-class HTS generator using 3-D finite-element analysis software to investigate the electromagnetic effects due to the structural-shape changes in the superconducting field coil.

To minimize most heat loss of current lead for high-temperature superconducting (HTS) rotating machine, the choice of conductor properties and lead geometry - such as length, cross section, and cooling surface area - are one of the various significant factors must be selected. Therefore, an optimal lead for large scale of HTS rotating machine has presented before. Not let up with these trends, this paper continues to improve of diminishing heat loss for HTS part according to different model. It also determines the simplification conditions for an evaluation of the main flux flow loss and eddy current loss transient characteristics during charging and discharging period.

Output fluctuation which is generated in wind power farm can hinder stability of total power system. The electric energy storage (EES) reduces unstable output, and superconducting magnetic energy storage (SMES) of various EESs has the proper performance for output compensation of wind power farm since it charges and discharges large scale power quickly with high efficiency. However, because of the change of current within SMES, the electromagnetic losses occur in the process of output compensation. In this paper, the thermal effect of the losses that occur in SMES system while compensating in wind power farm is analyzed. The output analysis of wind power farm is processed by numerical analysis, and the losses of SMES system is analyzed by 3D finite element analysis (FEA) simulation tool.

Various cooling systems for high-temperature superconducting (HTS) magnet applications were
analyzed and discussed before. Among these systems, solid nitrogen (SN2) hybrid-type cooling system
is one of a reliable, inexpensive, compact and stable one. The motivation of the study is to develop the
thermal characteristic of hybrid-type cooling system for HTS magnet applications – it includes the design
of an assembly of stacked second generation high temperature superconductor 2G HTS double pancake
coils, each of which is wound without turn-to-turn insulation. Then, heat-transfer analysis of the 2G HTS
magnet is carried out using 3D finite-element analysis (FEA) tool.

Large wind turbine generators with high temperature superconductors (HTS) are in incessant development because of their advantages such as weight and volume reduction and the increased efficiency compared with conventional technologies. In addition, nowadays the wind turbine market is growing in a function of time, increasing the capacity and energy production of the wind farms installed and increasing the electrical power for the electrical generators installed. As a consequence, it is raising the wind power energy contribution for the global electricity demand. In this study, a forecast of wind energy development will be firstly emphasized, then it continue presenting a recent status of the technology development of large scale HTSG for wind power followed by an explanation of HTS wire trend, cryogenics cooling systems concept, HTS magnets field coil stability and other technological parts for optimization of HTS generator design-operating temperature, design topology, field coil shape and level cost of energy, as well. Finally, the most relevant projects and designs of HTS generators specifically for offshore wind power systems are also mentioned in this study