Yagai Tsuyoshi

Bio: Yagai Tsuyoshi is an academic researcher from Sophia University. The author has contributed to research in topics: Scale (ratio). The author has an hindex of 1, co-authored 1 publications receiving 2 citations.

Commissioning tests of the Bonneville Power Administration 30 MJ superconducting magnetic energy storage unit

Abstract: A 30 MJ (8.4 kWh) Superconducting Magnetic Energy Storage (SMES) unit with a 10 MW converter has been installed and commissioned at the Bonneville Power Administration (BPA) substation in Tacoma, Washington. This is the first large-scale application in the US of superconductivity in an electric utility system. The unit, which is capable of absorbing and releasing up to 10 MJ of energy at a frequency of 0.35 Hz, was designed to damp the dominant power swing mode of the Pacific AC Intertie. This paper describes the electrical characteristics of the magnetic energy storage unit, its modes of operation, results of device tests, means for controlling real and reactive power, and some initial power system response tests. A short summary of the operating history of the unit over the first eleven months is also presented.

Application of SMES and fuel cell system combied with liquid hydrogen vehicle station to renewable energy control

Abstract: It is an urgent issue to reduce global carbon-dioxide in the world, and hence the renewable energy, that is environmentally friendly, should be supplied as a large amount of the electric power. Since installation of a large amount of the fluctuating renewable energy, such as wind turbine and photovoltaic, will cause the power utility network unstable, we propose an advanced superconducting power conditioning system (ASPCS) that is composed of Electrolyzer-Hydrogen-FC and SMES cooled with liquid hydrogen from a station for vehicles. The ASPCS has a function of compensating the fluctuating renewable energy with SMES that has quick response and large I/O power, and with that has moderate response and large capacity. The SMES is wound with superconductor with a critical temperature of 39 K from an economical point of view, because it is cooled with through a thermo-siphon system to keep safety against a flammable gas. The ASPCS effectively fulfills a power balance by applying a statistical prediction method of Kalman filter algorithm. The capacity of SMES is optimized by using the trend prediction for a number of wind power data. The overall electric efficiency of the ASPCS is evaluated for a typical wind generator.

SMES Model Device Cooled by Liquid Hydrogen Flow through Thermosiphon Loop

Abstract: A model of superconducting magnet energy storage device has been fabricated to demonstrate its cooling scheme by using liquid hydrogen flow through thermosiphon loops. A stack of three double pancake coils wound with MgB2 Rutherford cables are in thermal contact with thermosiphon pipes through pure copper plates which cover the each pancake coil surface. To prevent eddy current from being induced in the copper plates, the latter are slit into strips. After completion of the model device, performance test was carried out by actually supplying liquid hydrogen. The coil has been kept at a temperature lower than 21 K and has been charged up to a nominal current of 600 A. On the other hand, a large amount of evaporation of liquid hydrogen due to oscillation of some sort and gradual temperature rise at the coil terminals resulting in quench were observed, and these issues should be resolved in the future.