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A Tobit Kalman filter-based guidance system was proposed for expanding the capture region of missiles with a strapdown semiactive laser seeker. The characteristics of the semiactive laser seeker were analyzed, and the narrow field-of-view laser seeker model was used based on the analysis. A guidance filter was designed to utilize the saturated region of the seeker to overcome limited maneuverability arising from the narrow field-of-view range. A Tobit Kalman filter is adopted, and the prediction stage was modified so that the Tobit Kalman filter can be applied for nonlinear process models. The filter model for estimating the look angle, LOS angle, and LOS rate was formulated. The proposed guidance filter can estimate the state more robustly even if saturated measurements are given. This study showed that widening the available field-of-view range can lead to the expansion of the capture region. The impact angle control composite guidance and impact angle control guidance with bearing-only measurement were used for intercepting the target with the desired impact angle. Numerical simulations were performed to demonstrate the effectiveness of the proposed method in the saturated region of the seeker and show that the proposed method can expand the size of the capture region.

Objectives: The aim of this study was to evaluate the level of hematuria and the presence of clots during retrograde intrarenal surgery (RIRS) and miniaturized percutaneous nephrolithotomy (mPCNL) to predict surgical outcomes. Materials and Methods: The data of patients who underwent RIRS and mPCNL were analyzed separately. A hematuria grading (HG) system was classified into five grades based on the presence of blood clots and any visible stones according to the irrigation settings. Inter-observer reliability of the grading system was assessed using intra-class correlation and Spearman’s rho. Results: The HG system showed high agreement among examiners, with high intra-class reliability and a strong correlation between RIRS and mPCNL groups. The stone density of the Houns-field unit was the most important factor in determining the hematuria across the development and validation groups of RIRS and mPCNL patients. Multivariate logistic regression analysis showed that the HG system was a significant predictor for remnant stones in the PCNL group and the probability of acute pyelonephritis or sepsis in the RIRS group. The high hematuria group showed lower basketing difficulty with the basket with a blue marker instrument than with others. Conclusions: The new HG system shows excellent inter-observer reliability and a correlation with a gradual increase in stone density and surgical difficulty.

Distributed optical fiber sensors (DOFS) based on Raman, Brillouin, and Rayleigh scattering have recently attracted considerable attention for various sensing applications, especially large-scale monitoring, owing to their capacity for measuring strain or temperature distributions. However, ultraweak backscatter signals within optical fibers constitute an inevitable problem for DOFS, thereby increasing the burden on the entire system in terms of limited spatial resolution, low measurement speed, high system complexity, or high cost. We propose a novel resonance frequency mapping for a real-time quasi-distributed fiber optic sensor based on identical weak fiber Bragg gratings (FBG), which has stronger reflection signals and high sensitivity to multiple sensing parameters. The resonance configuration, which amplifies optical signals during multiple round-trip propagations, can simply and efficiently address the intrinsic problems in conventional single round-trip measurements for identical weak FBG sensors, such as crosstalk and optical power depletion. Moreover, it is technically feasible to perform individual measurements for a large number of quasi-distributed identical weak FBGs with relatively high signal-to-noise ratio (SNR), low crosstalk, and low optical power depletion. By mapping the resonance frequency spectrum, the dynamic response of each identical weak FBG is rapidly acquired in the order of kilohertz, and direct interrogation in real time is possible without time-consuming computation, such as fast Fourier transformation (FFT). This resonance frequency spectrum is obtained on the basis of an all-fiber electro-optic configuration that allows simultaneous measurement of quasi-distributed strain responses with high speed (>5 kHz), high stability (~2.4 με), and high linearity (R2 = 0.9999).

The development of scientific technology for art authentication have elicited multidimensional evidence to distinguish forgeries from original artworks. Here, we analyzed three-dimensional morphology of cracks that contain information such as painting features of artworks using an optical coherence tomography (OCT). The forgeries were produced by an expert from the original oil paintings with cracks that occur as paint drying, canvas aging, and physical damage. The parameters such as shape, width, and depth were compared based on cross-sectional images of original and fake cracks. The shapes of original cracks were a rectangular and an inverted triangle, but fake cracks were a relatively simple inverted triangle. The original cracks were as deep as the thickness of the upper layer and mostly have ‘thin/deep' or 'wide/shallow'. The fake cracks were observed as 'thin/shallow' or 'wide/deep'. This study will improve the understanding of the crack characteristics and promote development of techniques for art authenticity.

Optical coherence tomography (OCT) is a noninvasive imaging modality that can provide high-resolution, cross-sectional images of tissues. Especially in retinal imaging, OCT has become one of the most valuable imaging tools for diagnosing eye diseases. Considering the scattering and absorption properties of the eye, the 1000-nm OCT system is preferred for retinal imaging. In this study, we describe the use of an akinetic swept-source OCT system based on a pulse-modulated active mode locking (AML) fiber laser at a 1080-nm wavelength for in-vivo human retinal imaging. The akinetic AML wavelength-swept fiber laser was constructed with polarization-maintaining fiber that has an average linewidth of 0.625 nm, a spectral bandwidth of 81.15 nm, and duty ratio of 90% without the buffering method. We successfully obtained in-vivo human retinal images using the proposed OCT system without the additional k-clock and the frequency shifter that provides a wide field of view of 43.1°. The main retina layers, such as the retinal pigment epithelium, can be distinguished from the OCT image with an axial resolution of 6.3 μm with this OCT system.

We demonstrate a novel scheme for a full-field optical coherence tomography (FF-OCT) system using a tunable-path-difference source (TPDS). Recently, the comb-spacing-swept source (CSWS) method, including TPDS, has been successfully applied to improve the stability of three-dimensional (3D) time-domain (TD)-FF-OCT imaging by eliminating the mechanical scanning of the reference path, which has been the main source of undesirable noise in general TD-OCT. However, CSWS-OCT has the drawback of a degraded signal-to-noise ratio (SNR) from a duplicated interferometer structure. In this study, we improve the configuration of the TPDS so that it can be connected directly to the measurement interferometer, including the sample and reference paths of the OCT system. In our novel TPDS-OCT, a propagating optical path through only a single interferometer was critically helpful in enhancing the SNR while retaining the benefits of CSWS-OCT, and a free-space full-field interferometer of dual-input Mach–Zehnder type also has an even higher imaging performance owing to the simultaneous exposure of optical intensity into the camera and the short image acquisition time laterally. We theoretically and experimentally demonstrated the benefits of TPDS-OCT compared with CSWS-OCT in terms of SNR. We also demonstrated 3D multi-layered imaging, which CSWS-OCT cannot achieve owing to its limited SNR.

Optical interferometry using comb-swept lasers has the advantage of efficiently reducing the acquisition bandwidth for high-speed and long-range detection. However, in general, the use of a comb-swept laser involves a critical limitation in that the absolute distance cannot be measured, and, thus, multiple layers cannot be distinguished when measuring each position. This is because of the distance ambiguity induced by optical aliasing, in which there is periodic repetition of the frequency of an interferometric signal owing to discrete spectral sweeping, which does not occur in conventional optical interferometry that uses a continuous swept laser. In this paper, we introduce an optical Vernier sampling method using a dual-comb-swept laser to measure the absolute distances in a multi-layer target. For this, we designed a new type of dual-comb-swept laser to include two different free spectral ranges (FSRs) in separated wavelength bands to provide a stable lasing condition. Using a principle similar to that of a Vernier caliper for length measurement, the two different FSRs can be used to recover a higher frequency of an optical interferometric signal to measure longer distances from different layers in a target. Using the dual-comb-swept laser in optical interferometry, we solved the optical aliasing issue and measured the absolute distances of three layers separated over 83 mm using a point-scanning imaging setup and the simultaneous absolute distance of the top surfaces separated over 45 mm using a full-field imaging setup at 14 and 8 times lower acquisition bandwidth than a conventional continuous swept laser that is based on optical interferometry.

We report on an akinetic actively-mode-locked wavelength-swept laser (ASL) with a sweep that is highly linear in wavenumber. We demonstrate a nearly linear relationship between wavenumber and modulation frequency by using a chirped fiber Bragg grating (CFBG) in the cavity. By tailoring the drive waveform of the intracavity modulator, the wavenumber sweep was further linearized to enable high fidelity frequency-domain interferometric ranging without resampling of the acquired data. Used for catheter-based optical coherence tomography, the ASL showed comparable imaging performance to a state-of-art polygon-based wavelength-swept source at a matching sweep rate of 103.6 kHz, a duty cycle of 95%, and a bandwidth of 100 nm, centered at 1330 nm.

A new type of quasi-distributed sensor system is implemented using an active mode locking (AML) laser cavity with multiple partially reflecting segments. The mode locking frequency of the AML laser is linearly proportional to the overall lasing cavity length. To implement multiple resonators having multiple reflection points installed in a sensing fiber, two types of partial reflectors (PRs) are implemented for an in-line configuration, one with fiber Bragg grating and the other with a fiber Fabry&ndash, Perot interferometer. Since the laser has oscillated only when the modulation frequencies for the mode locking frequency match with the corresponding resonator lengths, it is possible to read the multiple partially reflecting segments along the sensing fiber. The difference between two corresponding mode locking frequencies is changing proportionally with the segment length variation between two PRs upon strain application. The segment length change caused by the applied strain can be successfully measured with a linear sensitivity between mode locking frequency and displacement, linearity over 0.99, and spatial position resolution below meter order.

The interaction between wireless sensors such as Internet of Things (IoT) and Cloud is a new paradigm of communication virtualization to overcome resource and efficiency restriction. Cloud computing provides unlimited platform, resources, services and also covers almost every area of computing. On the other hand, Wireless Sensor Networks (WSN) has gained attention for their potential supports and attractive solutions such as IoT, environment monitoring, healthcare, military, critical infrastructure monitoring, home and industrial automation, transportation, business, etc. Besides, our virtual groups and social networks are in main role of information sharing. However, this sensor network lacks resource, storage capacity and computational power along with extensibility, fault-tolerance, reliability and openness. These data are not available to community groups or cloud environment for general purpose research or utilization yet. If we reduce the gap between real and virtual world by adding this WSN driven data to cloud environment and virtual communities, then it can gain a remarkable attention from all over, along with giving us the benefit in various sectors. We have proposed a Pub/Sub-based sensor virtualization framework Cloud environment. This integration provides resource, service, and storage with sensor driven data to the community. We have virtualized physical sensors as virtual sensors on cloud computing, while this middleware and virtual sensors are provisioned automatically to end users whenever they required. Our architecture provides service to end users without being concerned about its implementation details. Furthermore, we have proposed an efficient content-based event matching algorithm to analyze subscriptions and to publish proper contents in a cost-effective manner. We have evaluated our algorithm which shows better performance while comparing to that of previously proposed algorithms.

A hardware implementation of MOD(moving object detection) algorithm using EGML(effective Gaussian mixture learning)- based background subtraction to detect moving objects in video is described. Some approximations of EGML calculations are applied to reduce hardware complexity, and pipelining technique is adopted to improve operating speed. The MOD processor designed in Verilog-HDL has been verified by FPGA-in-the-loop verification using MATLAB/Simulink. The MOD processor has 2,218 slices on the Virtex5-XC5VSX95T FPGA device and its throughput is 102 MSamples/s at 102 MHz clock frequency. Evaluation results of the MOD processor for 12 images in the IEEE CDW-2012 dataset show that the average recall value is 0.7631, the average precision value is 0.7778 and the average F-measure value is 0.7535.

An analysis of hardware design conditions of moving object detection (MOD) algorithm is described, which is based on effective Gaussian mixture learning (EGML). A simulation model of EGML algorithm is implemented using OpenCV, and the effects of some parameter values on background learning time and MOD sensitivity are analyzed for various images. In addition, optimal design conditions for hardware implementation of EGML-based MOD algorithm are extracted from fixed-point simulations for various bit-widths of parameters. The proposed fixed-point model of the EGML-based MOD uses only half of the bit-width at the expense of the loss of MOD performance within 0.5% when compared with floating-point MOD results.

POSCO and the Research Institute of Industrial Science and Technology developed a 10-kW superconducting synchronous generator using high-temperature superconducting wire. The generator consists of four-pole racetrack-type superconducting coils using GdBCO wire for rotor and 24 slots copper windings for stator. The rated power of the generator was 10 kW at 600 r/min, and the operating temperature was 30 K by thermosyphon cooling method using liquid neon. The output power was measured when the generator was connected to a vector motor, and the detailed results were discussed in this paper.

This paper proposes a three-phase four-leg voltage sourced inverter (VSI) based load unbalance compensator (LUC) including its control algorithm, which is a component of a microgrid. The purpose of proposed three-phase four-leg VSI based LUC is to improve power quality of the standalone microgrid. Power quality of the microgrid which was installed in Mara-island, Korea is analyzed using a real operational data. In this work, the microgrid in Mara-island which includes a photovoltaic power generation system, a diesel generator, a battery energy storage system, and a power management system is modeled in PSCAD/EMTDC, and proposed three-phase four-leg VSI based LUC is also modeled and applies to the modeled microgrid. Power flow and stability of the modeled microgrid with the LUC is analyzed under variable irradiance and unbalance loads. The results show that the proposed LUC helps to improve stability of the stand-alone microgrid. The proposed three-phase four-leg VSI based LUC and its control algorithm can be effectively utilized to the stand alone microgrid which has large unbalance loads.

A wind farm is a collection of a few tens or a few hundreds of wind turbine generator installed in close vicinity. There is a need for further research to examine the performance of wind farm and w...

A hardware-in-the-loop simulation (HILS) method for a wind farm controller using a real time digital simulator (RTDS) is presented, and performance of the wind farm controller is analyzed. A 100 MW wind farm which includes 5 MW wind power generation systems (WPGS) is modeled and analyzed in RSCAD/RTDS. The wind farm controller is implemented by using a computer, which is connected to the RTDS through transmission control protocol/internet protocol (TCP/IP). The HILS results show the active power and power factor of the wind farm, which are controlled by the wind farm controller. The proposed HILS method in this paper can be effectively utilized to validate and test a wind farm controller under the environment in practice without a real wind farm.

High temperature superconducting magnetic energy storage (HTS SMES) is known as an effective solution to significantly decrease the voltage and power fluctuations of grid connected wind power generation system (WPGS). This paper implements an effective control scheme of a back-to- back converter with shunt-connected HTS SMES for the frequency regulation of an islanded microgrid. The back-to-back converter is used to connect the WPGS to the grid. A large-scale HTS SMES is linked to the DC side of the back-to-back converter through a two-quadrant DC/DC chopper. An adaptive control strategy is implemented for the back-to-back converter and the two-quadrant DC/DC chopper to improve the efficiency of the whole system. The performance of the proposed control system was evaluated in a test power system using PSCAD/EMTDC. The simulation results clearly show that the back-to-back converter with shunt-connected HTS SMES operates effectively with the proposed control strategy for stabilizing the power system frequency fluctuations.

We demonstrate a novel narrow-linewidth configuration of a wavelength-swept active mode locking (AML) fiber laser. The frequency response of the modulation depth of a semiconductor optical amplifier can be improved in a higher modulation frequency region by adapting the cross gain modulation (XGM) configuration, compared to that of the conventional direct gain modulation (DGM) configuration. As a sufficient modulation depth is implemented for an AML at higher modulation frequencies at around gigahertz order, it results in a narrower linewidth of lasing output. For the same modulation frequency of 1361.25 MHz, the linewidth of 0.25 nm with DGM becomes narrower up to 0.113 nm with XGM, which corresponds to an improved point spread function with 1.41 mm of 6-dB roll-off.

A multi-spectral laser speckle contrast imaging (MS-LSCI) system is proposed using only a single wavelength-swept laser, which provides both highly coherent and multi-spectral outputs to simultaneously generate laser speckle contrast images and multi-spectral images, respectively. Using a laser light swept from 770 to 821 nm at a repetition rate of 5 Hz and a CCD camera of 335 fps, 67 multi-spectral frame images are acquired in 0.76 nm wavebands over 51 nm spectral range. The spectral sub-windowing method of single wavelength-swept laser source is used to solve the lack of spectral information from a few individual light sources, which is a limitation of conventional MS-LSCI systems. In addition to the speckle flow index from the LSCI frames, the multi-spectrally encoded images can generate additional images of spectral absorbance. To further examine the performance of the MS-LSCI system, an in vivo cuff-induced ischemia experiment was conducted to show the real-time imaging of hemodynamic and blood oxygen saturation changes simultaneously over the entire 2.5 cm×4.5 cm field of view.

The authors designed a high temperature superconductor (HTS) racetrack coil for a 10 MW class superconducting synchronous wind turbine generator. The designed HTS racetrack coil was analyzed by an electromagnetic finite element method (FEM) to determine the magnetic field distribution, inductance, stress, etc. This paper describes the stress analysis and structure design result of the HTS racetrack coil for 10 MW class superconducting synchronous wind turbine generators, considering orthotropic material properties, a large magnetic field, and the resulting Lorentz force effect. Insulated HTS racetrack coils and no-insulation HTS racetrack coils were also considered. According to the results of the stress analysis, the no-insulation HTS racetrack coil results were better than the insulated HTS racetrack coil results.

International Electronical Committee (IEC) 61850-90-7 is a part of the IEC 61850 series which specifies the advanced functions and object models for power converter based Distributed Energy Resources (DERs). One of its functions, the Voltage/VAR (V/V) control function, is used to enhance the stability and the reliability of the voltage in the distribution system. The conventional V/V function acts mainly for flattening the voltage profile as for a basic grid support function. Currently, other objectives such as the minimization of line loss and the operational costs reduction are coming into the spotlight. In order to attain these objectives, the V/V function and hence the DER units shall actively respond to the change of distribution system conditions. In this paper, the modification of V/V function and new requirements are proposed. To derive new requirements of V/V function, loss minimization is applied to a particle swarm optimization (PSO) algorithm where the condition of voltage constraint is considered not to deteriorate the voltage stability of the distribution system.

—An HTS (high temperature superconducting) coil without insulation has been investigated since a metallic insulation was suggested in the mid-1980s. The advantage of an insulationless HTS pancake coil is that it is more stable than an insulated HTS pancake coil. This paper focuses on the various characteristics of the insulationless HTS pancake coil related with stability, especially under the external magnetic field. Because HTS pancake coil may be influenced by the external magnetic field in a real operational environment of electrical devices. First, charge-discharge test was performed for the characteristics evaluation of the insulationless HTS pancake coil as compared with insulated HTS pancake coil in liquid nitrogen at 77 K. Based on the experiment results, characteristics evaluation of the insulationless HTS pancake coil was implemented under the external magnetic field. In order to carry out the experiment, we have fabricated a cylindrical solenoid coilto apply the magnetic field. The various characteristics of the insulationless HTS pancake coil were evaluated forcharge-discharge and over-current conditions. This paper proves that the insulationless HTS pancake coil more is stable than the insulated HTS pancake under the external magnetic field.

Recently, the small scale photovoltaic (PV) electronic devices are drawing attention as the upcoming PV generation system. The PV system is commonly used in small scale PV applications such as LED lighting and cell phone. This paper proposes photovoltaic output sensorless (POS) maximum power point tracking (MPPT) control for a small scale charging system of PV-nickel metal hydride battery using field-programmable gate array (FPGA) controller. A converter is connected to a small scale PV cell and battery, and performs the POS MPPT at the battery terminal current instead of being at the PV cell output voltage and current. The FPGA controller and converter operate based on POS MPPT method. The experimental results show that the nickel metal hydride battery is charged by the maximum PV output power.

Due to enhanced demands on quality, security and reliability of the electric power energy system, a microgrid has become a subject of special interest. In this paper, output characteristics of energy storage system (ESS) with an electric double layer capacitor (EDLC) and battery energy storage system (BESS) of a renewable energy based microgrid were analyzed under grid-connected and islanded operation modes. The microgrid which consists of photovoltaic and wind power turbine generators, diesel generator, ESS with an EDLC, BESS and loads was modeled using real time digital simulator. The results present the effective control patterns of the microgrid system.

The operation of permanent magnet synchronous generator (PMSG) type wind power generation system (WPGS) can be affected by the utility condition. Consequently, transient condition of utility should be analyzed for the safe and reliable operation of WPGS. This paper presents transient analysis results of a PMSG type WPGS using real time digital simulator (RTDS). A fault condition was applied to the transient analysis of PMSG type WPGS as the transient grid condition. The simulation results were analyzed to show the operational characteristic of PMSG type WPGS under the transient phenomenon of utility.

This paper analyses operating characteristic of high temperature superconducting magnetic energy storage (HTS SMES) for frequency stabilization of dispersed power generation system. The wind power generation system (WPGS) fluctuates due to wind speed variation and affects the frequency and voltage fluctuations of the utility. SMES is probably a key technology to overcome these fluctuations. To stabilize power system frequency, a large-scale HTS SMES is connected to the terminal of the WPGS. The authors analysed the load side frequencies using two different configurations of SMES, one consisting of a single magnet and the other of a dual magnet. From the simulation results, it can be concluded that the SMES is a useful device for stabilizing the power system frequency fluctuations, and a dual magnet type SMES is more effective for frequency stabilizing but exhibits more AC loss due to the increased operating current than a single magnet type.

The Superconducting Magnetic Energy Storage (SMES) system is a key technology for overcoming the voltage sag, swell, interruption, and frequency fluctuation with the fast response speed of current charge and discharge. A toroidal-type SMES is designed using a 3D CAD program, and the inductance and AC loss characteristic during operation are analysed using Finite Element Method (FEM) program. The toroidal-type magnet consists of 30 double pancake coils (DPC). The single pancake coils (SPC), constituting the double pancake coils, are arranged at an angle of 6° from each other, based on the central axis of the toroidal-type magnet. The conduction cooling method is used for the toroidal-type SMES cooling. To evaluate the characteristics of the over-mega-joule class grid-connected HTS SMES system, the authors implemented a simulation by which the SMES coil could be connected to the Real Time Digital Simulator (RTDS). Using the simulation, users can perform voltage sag and frequency stabilization simulations with a real SMES coil in real time and easily change the capacity of the SMES system as much as they need. The effectiveness of the toroidal-type HTS SMES system is demonstrated through the RTDS-based simulation and the results are briefly discussed.

Superconducting magnetic energy storage (SMES) system is getting increasing acceptance in variation applications of power system because of its higher efficiency and faster response. This paper proposes a high quality power conditioner system for the SMES system operation. The power conditioner consists of a voltage source converter using IGBT (Insulated Gate Bipolar Transistor). In order to compensate several problems such as voltage sag and harmonic current flowing in to utility, active filter systems could be a good solution method. SMES is a very good promising source due to the high response time of charge and discharge. This paper presents a simulation technique for a decision method of the specification of the active filter system combined with SMES system. Through the results of several analyses and simulations carried out by PSCAD/EMTDC, this paper demonstrates the significant effect of the control by SMES on the improvement of power system performance. Based on this simulation, authors developed a power conditioner connected to the utility system. It was shown that the developed power conditioner was well-designed and effective.

A practical design method for supersonic wings has been developed. The method is based on Takanashi`s method that uses integral equations and iterative "residual-correction" concept. The geometry correction is calculated by solving linearized small perturbation equation (LSP) with the difference between garget and objective surface pressure distributions as a boundary condition. In the present method, LSP equation is analytically transformed to integral equations by using the Green`s theorem. Design results of an isolated wing and wing-nacelle configurations are presented here.

Recently, gearless type generators, which have very low rotation speed and high torque, have been preferred over the geared type due to the problem of the gearbox reliability. In particular, a high-temperature superconducting generator is promising for wind power applications because of its advantages of weight, size, and efficiency. In this paper, a 10-MW class superconducting wind power generator is designed using Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O wires, and the weight of the superconducting generator is estimated. The finite elements method is used to analyze the magnetic field distribution, and the 3-D CAD program is used to calculate the weight of the super-conducting synchronous generator. The designed 10-MW class superconducting generator is analyzed and discussed considering the proper weight. The designed 10-MW superconducting generator will be effectively utilized in the construction of the 10-MW class wind power generation system.

A superconducting synchronous generator (SCSG) is suitable for designing a large-scale wind power generation system, because of its lighter weight and higher torque as compared to conventional generators. This paper analyzes a 10-kW SCSG designed by the finite element method. The finite element method tool is used to evaluate the designed 10-kW SCSG, which has 16 double pancake coils of race-track type with coated conductor tape according to the component certification (IEC 60034) for a wind power generator. The results show several specific characteristics of the designed SCSG. The results can also effectively evaluate the SCSG for a wind turbine, before the scale-up design and fabrication of the generator.

This paper considers the insulationless high-temperature superconducting (HTS) magnet as a new and innovative concept for dc applications due to its benefits as compared to conventional HTS magnets with insulation layers between HTS conductors. The purpose of this paper is to study the operating characteristics of an insulationless HTS magnet. The normal operating characteristics of the insulationless HTS magnet were investigated according to the various current levels. Thermal stability of the insulationless HTS magnet was also analyzed. The critical current of the insulationless HTS magnet was measured at 40 K. The temperature distribution of the insulationless HTS magnet was measured using thermocouples. The experiment results demonstrate superior thermal stability characteristics in the insulationless HTS magnet. Thus, it is confirmed that the thermal performance of large-scale HTS magnets can be enhanced by applying insulationless magnets instead of general insulated HTS magnets.

It is important to analyze the transient characteristics of large synchronous generators according to the trend of the extension of wind turbines. The fabricated field coil of a synchronous generator using high-temperature superconducting (HTS) wire is somewhat influenced by the external magnetic field of the stator in a real environment. This paper describes the electromagnetic analysis of an HTS field coil of a 10-MW superconducting synchronous generator during stator winding faults. The real-time digital simulator is used to simulate a fault condition of the 10-MW SCSG. Also, the finite-element method is used in each operating condition, including normal and transient conditions, to analyze the influence of the HTS field coil. Based on the simulation results discussed here, there do not appear to be any significant problems regarding the electromagnetic operation of the HTS field coil during transient conditions of the stator. This paper will be used in the analysis of the transient characteristics of a large superconducting synchronous generator during stator winding faults.

It is believed that the size of wind turbines on offshore wind farms can be increased up to 10 MW. A superconducting synchronous generator (SCSG) is advantageous to a large-scale wind turbine because of its weight and volume. In this paper, a grid-connected large-scale superconducting wind turbine generator is analysed under varying wind speeds. A 10 MW SCSG is designed by the finite elements method (FEM). The parameters of the designed SCSG are calculated and applied to a modeled SCSG in a Power System Computer Aided Design/Electromagnetic Transients including DC. The electric and dynamic performances of superconducting wind turbine generators are analysed in this simulation. This paper shows the effectiveness of the grid-connected superconducting wind turbine generator for offshore applications.

In order to improve the efficiency of wind power generation system (WPGS), many researchers have tried to develop a larger WPGS and a superconducting synchronous generator (SCSG) has been suggested to develop over 5 MW class WPGS. There are two expected types of drive-train, geared and gearless. The structure and electrical parameters of the SCSG depend on the type of drive-train used. This paper deals with a comparative analysis of the 10 MW class geared and gearless types of the SCSG for WPGS. Three drive-trains are designed for the 10 MW class SCSGs using the finite elements method analysis tool. The PSCAD/EMTDC is utilized to simulate electrical and dynamic behaviors of the modeled SCSGs. The simulation results show the operation characteristics of the designed SCSGs and suggest that the single-stage gearbox type drive-train is the most efficient drive-train for the SCSG due to the reduction of the number of rotor poles and the volume of the generator, even though the geared-type drive-train requires periodical maintenance.