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High-temperature superconducting (HTS) transformers have a promising feature in reduction of total weight, total size, and the losses of large-scale distribution transformers. However, the lower leakage reactance of HTS transformers results in a higher short-circuit fault currents and electromagnetic forces. Therefore, optimization of short-circuit electromagnetic forces is one of the crucial aspects in the design of HTS transformers. In this paper, a novel analytical method is proposed for determination of optimum distributive ratios resulting in minimization of these forces for asymmetrical multi-segment windings of an HTS transformer. Employing these distributive ratios, radial and axial... 

High-temperature superconducting (HTS) transformers have remarkable appealing advantages over conventional ones. But higher brittleness of HTS windings with respect to copper windings makes HTS transformers more vulnerable in short circuit and inrush current situations. During tap changer operation, appreciable asymmetry and non-uniform distribution of ampere-turn along the windings causes high axial component of short circuit forces and makes the situation more severe. In this paper, multi-segment winding method is employed for reduction of axial short circuit forces. An analytical method is presented for calculation of axial component of short circuit forces under tap changer operation.... 

Growing interest in high-temperature superconducting (HTS) power devices is the result of commercial availability of the HTS tapes. One of the most promising applications of the HTS technology is HTS transformer. Flux diverters are used for critical current elevation in HTS transformer windings. In this paper multilayered flux diverter arrangements have been introduced to reduce weight and losses of conventional solid flux diverter arrangement. Horizontal and vertical multilayered arrangements have been investigated and compared with solid arrangement. Two dimensional (2D) finite element method (FEM) simulations have been used for comparison between different arrangements  

Mitigation and control of leakage fluxes and short circuit forces needs much more attention, for a high-temperature superconducting (HTS) transformer, than for a conventional one. Different methods such as the application of auxiliary windings, multi-segment winding, and flux diverter have been presented in the literatures for leakage magnetic field reduction in HTS transformers. In this paper, for the first time, optimal design of auxiliary windings has been performed for a 132/13.8 kV, 50 MVA three phase core type HTS transformer. Genetic algorithm (GA) has been used for the optimization process. Induced current in auxiliary windings which is inversely proportional to the leakage fluxes... 

Presence of defects, conducting particles, nonconducting particles, and nitrogen gas bubbles in the insulation system of high-temperature superconducting (HTS) transformers, mainly inside the liquid nitrogen as its major insulation, can create local field enhancement and consequently partial discharges which eventually lead to the catastrophic failure of the transformer. In this paper, two-dimensional (2D) axisymmetric finite element method (FEM) modeling via COMSOL Multiphysics software has been utilized for the investigation of the impact of size and shape of conducting particles and nitrogen gas bubbles on partial discharge (PD) activities in liquid nitrogen. Conducting particles of... 

The appealing advantages of high-temperature superconducting (HTS) power transformers over conventional ones have attracted transformer manufacturing companies, power companies, research institutes, and universities worldwide to conduct research and development in this field. Unfortunately, HTS transformers are more vulnerable to mechanical stresses than conventional transformers. The results of the interaction between current carrying windings and leakage magnetic fluxes are the electromagnetic forces, which act on transformer windings. Under short circuit events, these forces are remarkable, and, therefore, catastrophic failure of transformer may arise. Flux-diverter applications have been... 

Appealing advantages of high-temperature superconducting (HTS) transformers are very promising for the contemporary and future power delivery systems. Cryogenic insulation technology is one of the key technologies for their commercialization. In this paper insulation design of the end part of cryogenic high voltage (H. V.) bushing of a 230/20 kV HTS transformer is developed. Analytical relations and finite element method (FEM) modelling, through application of COMSOL Multiphysics software, are employed for determination of electric field distribution in this design process. Weibull 0.1% dielectric breakdown strength has been considered as criterion for insulation design. Different shape and... 

3D wound core is a newly proposed core structure, which is used for construction of distribution transformers. Although many advantages have been proposed for transformer with 3D wound core and it has found increasing application in some countries such as China and Iran, no model has been presented so far in the literature for such transformers. In this paper, a low frequency model, derived based on the duality principle for transformer with 3D wound core, which can be used for both steady state and low-frequency transient studies. The validity of the model in steady state condition is then verified by experimental results. © 2017 IEEE  

High-temperature superconducting (HTS) transformers have a promising feature in reduction of total weight, total size, and the losses of large-scale distribution transformers. However, the lower leakage reactance of HTS transformers results in a higher short-circuit fault currents and electromagnetic forces. Therefore, optimization of short-circuit electromagnetic forces is one of the crucial aspects in the design of HTS transformers. In this paper, a novel analytical method is proposed for determination of optimum distributive ratios resulting in minimization of these forces for asymmetrical multi-segment windings of an HTS transformer. Employing these distributive ratios, radial and axial... 

High-temperature superconducting (HTS) transformers with multi-segment windings have been proposed in earlier literatures for the hysteresis loss reduction and short circuit electromagnetic force mitigation. The optimum distributive ratios for these multi-segment windings have been determined in earlier literatures. Asymmetrical seven segment winding with its optimum distributive ratio (k = 1/12) results in minimization of short circuit electromagnetic forces under normal tap and any adjusted tap. However, insulation design and leakage inductance calculation for the multi-segment winding of an HTS transformer have not been addressed in past literatures. Insulation design is one of the most... 

Utilization of superconducting equipment increases every day due to availability of the HTS tapes with reasonable prices, commercially. Since 1997, many high-temperature superconducting (HTS) transformers have been designed and fabricated. In this paper, all the different developments of HTS transformer windings since 1997 will be reviewed. Additionally, the advantages and disadvantages of the application of the two main winding types (the pancake and the layer) in the HTS transformer will be studied. © 2020, Springer Science+Business Media, LLC, part of Springer Nature  

Delivery of the Smart Grid is a topic of considerable interest within the power industry in general, and the IEEE specifically. This paper presents the smart grid landscape as seen by the IEEE Dielectrics and Electrical Insulation Society (DEIS) Technical Committee on Smart Grids. We define the various facets of smart grid technology, and present an examination of the impacts on dielectrics within power assets. Based on the trajectory of current research in the field, we identify the implications for asset owners and operators at both the device level and the systems level. The paper concludes by identifying areas of dielectrics and insulation research required to fully realize the smart... 

A novel intelligent semi-active control system for an eleven degrees of freedom passenger car's suspension system using magnetorheological (MR) damper with neuro-fuzzy (NF) control strategy to enhance desired suspension performance is proposed. In comparison with earlier studies, an improvement in problem modeling is made. The proposed method consists of two parts: a fuzzy control strategy to establish an efficient controller to improve ride comfort and road handling (RCH) and an inverse mapping model to estimate the force needed for a semi-active damper. The fuzzy logic rules are extracted based on Sugeno inference engine. The inverse mapping model is based on an artificial neural network... 

Using CNG as an additive for gasoline is a proper choice due to higher octane number of CNG enriched gasoline with respect to that of gasoline. As a result, it is possible to use gasoline with lower octane number in the engine. This would also mean the increase of compression ratio in SI engines resulting in higher performance and lower gasoline consumption. Over the years, the use of simulation codes to model the thermodynamic cycle of an internal combustion engine have developed tools for more efficient engine designs and fuel combustion. In this study, a thermodynamic cycle simulation of a conventional four-stroke spark-ignition engine has been developed. The model is used to study the... 

With the declining energy resources and increase of pollutant emissions, a great deal of efforts has been focused on the development of alternatives for fossil fuels. One of the promising alternative fuels to gasoline in the internal combustion engine is natural gas [1-5]. The application of natural gas in current internal combustion engines is realistic due to its many benefits. The higher thermal efficiency due to the higher octane value and lower exhaust emissions including CO2 as a result of the lower carbon to hydrogen ratio of the fuel are the two important feature of using CNG as an alternative fuel. It is well known that computer simulation codes are valuable economically as a cost... 

Gaining insight into possible vibratory responses of dynamical systems around their stable equilibria is an essential step, which must be taken before their design and application. The results of such a study can significantly help prevent instability in closed-loop stabilized systems by avoiding the excitation of the system in the neighborhood of its resonance. This paper investigates nonlinear oscillations of a rotary inverted pendulum (RIP) with a full-state feedback controller. Lagrange’s equations are employed to derive an accurate 2-DoF mathematical model, whose parameter values are extracted by both the measurement and 3D modeling of the real system components. Although the governing... 

A suction-controlled ring device has been developed to continuously measure the coefficient of lateral soil pressure in deformable unsaturated soil samples from the at-rest to the active condition under application of increasing vertical pressure and controlled matric suction. The device incorporates a thin aluminum specimen ring equipped with horizontal strain gages for recording the lateral soil strains. In addition, a sensor recording water volume changes is utilized to continuously monitor the degree of saturation of the soil sample during tests. The matric suction within the soil texture is controlled using the axis translation technique. In order to verify the performance of the ring... 

We introduce a new smooth, non-toxic, biocompatible method for cross-linking of gum tragacanth (GT), a polysaccharide of natural origin, in order to serve as a new supporting matrix for immobilization systems. The modified gum is used as a matrix for the catalysis of the conversion of benzyl penicillin to 6-aminopenicillanic acid (6-APA) by means of Escherichia coli ATCC11105 with penicillin G acylase (PGA) activity. The results show that GT beads can not only serve as a proper matrix for immobilization, but show enhanced hydrolysis rate and stability compared to other immobilization systems used for this reaction. This signifies the potential of GT as a biocompatible matrix for...