• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.13-16
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• 1988

As the automic power plant is increased, load leveling energy storage system becomes more important. Pumped hydroelectric storage, used in the present, has too storage efficiency and difficulty in selecting site. But SMES(Superconducting Magnet Energy Storage) has high storage efficiency (90%), fast time response characteristics and ease of location. The general object of SMES with electric power system is the minimization overall production cost. This paper presents a method for the economic operation of SMES by Dynamic Programming.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.124-129
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• 1994

We have developed a stabilizing SMES with 0.5MJ energy storage capacity through all the research process of the system planning, magnet drawing, which including various kinds of evaluation for the optimized system organization. This research performance is considered to be very distinguished one. Besides, the acquired knowledge and many experiences getting through the performance of the study are much benefitful to other studies concerning with a development of superconducting electrical power machines. This paper gives the general presentation of the study and many kindes of expermental results including analysis of them.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.79-84
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• 2008

We are developing a small-sized high temperature superconducting magnetic energy storage (HTS-SMES) magnet with the nominal storage capacity of 600 kJ, which provides electric power with high quality to sensitive electric loads. Critical current and N-value of a high temperature superconductor with large current, which was selected for the development of the 600 kJ HTS-SMES magnet, were investigated in various oblique external magnetic fields. Based on the critical current and N-value measured for the short sample conductor, we discussed the DC V - I characteristic of a model coil fabricated with the same conductor of 500 m. The results show that the measured critical current and N-value of the conductor for parallel field are constant in external magnetic fields less than about 0.2 T. However, for oblique fields, its critical current and N -value abruptly decrease in all external magnetic fields. Moreover, the measured critical current of the model coil well agrees with the numerically calculated one based on the DC V - I characteristic measured for the short sample conductor. This suggest that losses and critical currents for an HTS-SMES magnet made up of a high temperature superconductor with anisotropic characteristic are predictable from the data of a short sample conductor.

• Progress in Superconductivity and Cryogenics
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• v.12 no.1
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• pp.28-31
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• 2010

A magnetic field calculation method for toroidal type winding which has circular section was developed. At first, the equation for magnetic field by single filament coil was extended using numerical integration to estimate the entire interesting region of solenoid, especially winding region itself. And then, the magnetic field by toroidal arrangement of solenoids was computed with a coordinate transformation of vector fields. The superconducting magnet with toroidal arrangement can be made up of several tens of solenoid type double pancake windings for some applications such as superconducting magnetic energy storage system(SMES). In this system, the field calculation on the high-Tc superconducting(HTS) tape itself is very important because the entire system can be reached to a fault by magnetic stress of conductor or the critical current of superconducting tape can be dramatically reduced under its self field condition. To make matters worse, 3-dimensional analysis is indispensable for this type of magnet and the most of commercial programs with finite element method can be taken too much time for analysis and design. In this paper, a magnetic field calculation method for toroidal type winding with circular section was induced.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.305-309
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• 1999

This paper presents an high efficiency energy conversion system for very high-speed flywheel energy storage system using high Tc superconducting bearings. Main configuration of power convertor is designed to replace of the conventional battery with EMB(Electro Mechanical Battery). PMSM(Permanent Magnet Synchronous Motor) using Halbach array is used as the energy conversion system of motor and generator. Some PWM methods for the high frequency inverter is described and the power factor effects to the torque characteristics and efficiency of the motor and generator is analyzed. As the results, it is verified that the inverter output current is well regulated to be in-phase or inverse-phase sinusoidal waveform to have the wide operational range from 2,500rpm to 42,000rpm. Proposed circuit is designed to obtain the very high speed, high efficiency and stable rotational characteristics, and to be applied to1.2r[kW]/65[Wh] system.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.535-537
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• 2009

As a kind of high Tc superconductor application technique, a study on the development of energy storage device system using BiPbSrCaCuO superconductor was performed. Chemical melt process was developed to gabricate the high magnetization superconductor which is needed to develop the energy saving system and the effect of various process variable on the superconducting properties of the specimens were tested and analyzed. Magnetochemical interactions between superconductor and permanent magnet was also experimented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.685-688
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• 2006

A single-phase uninterruptible power supply system suitable for a SMES unit is proposed to achieve a simple circuit configuration and higher system reliability. It reduces the number of switching devices by applying a common-arm scheme. Operational principles to normal, stored-energy, and bypass mode are discussed in detail. Eliminating some of the switches or substituting passive components for active switches generally increases the sophistication and reduces degree of freedom in control strategy. However, the high-performance digital controller ran execute the complicated control task with no additional cost. The validity of the proposed UPS system will be verified by a computer-aided simulation.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.807-809
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• 2000

We are developing a small-sized superconducting magnetic energy storage ($\mu$ SMES) magnet with the storage capacity of a few megajoules, which provides electric power with high quality to sensitive electric loads. As the earlier step of the fabrication of the $\mu$ SMES magnet, this paper describes recovery current experimental results of a kA class superconductor. Recovery current of a superconductor was tested in two points of copper ratio and cooling effect.

• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.50-54
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• 2022

High temperature superconducting (HTS) magnets for large-capacity energy storage system need to be composed of toroid magnets with high energy density, low leakage magnetic fields, and easy installation. To realize such a large capacity of a toroid HTS magnet, an HTS cable with large current capacity would be preferred because of the limited DC link voltage and instantaneous high power required for compensation of the disturbance in the power grid. In this paper, the optimal operating strategies of the SMES for peak load reduction of the microgrid system were calculated according to the load variation characteristics, and the effect of compensation of the frequency change in microgrid with a SMES were also simulated. Based on the result of the simulation, key design parameters of SMES coil were presented for two cases to define the specification of the HTS cable with large current capacities for winding of HTS toroid coils, which will be need for development of the HTS cable as a future work.

• Progress in Superconductivity and Cryogenics
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• v.3 no.2
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• pp.5-9
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• 2001

For the development of a small-sized superconducting magnetic energy storage($\mu$SMES) system we designed, fabricated and tested a model coil consisting of five coils with different features. e.g. winding tensions. bore diameters and materials. cooling channels. The results show that even in the highly pre-stressed small coil the quench currents of the coils are degraded to about 70% of their coils critical current. The quench currents of the coils with natrow cooling channels are two times as high as that of the coil without spacers. The test results also indicate that the usual training effect depends on the winding tensions of the coils according to materials of the bobbin.