While energy storage technologies do not represent energy sources, they provide valuable added benefits to improve stability power quality, and reliability of supply. Battery technologies have improved significantly in order to meet the challenges of practical electric vehicles and utility applications. Flywheel technologies are now used in advanced nonpolluting uninterruptible power supplies. Advanced capacitors are being considered as energy storage for power quality applications. Superconducting energy storage systems are still in their prototype stages but receiving attention for utility applications. The latest technology developments, some performance analysis, and cost considerations are addressed. This paper concentrates on the performance benefits of adding energy storage to power electronic compensators for utility applications.

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Energy storage systems for advanced power applications

Exploring dynamics in the far-infrared with terahertz spectroscopy.

Superconducting magnetic energy storage (SMES) is known to be a very good energy storage device. This article provides an overview and potential applications of the SMES technology in electrical power and energy systems. SMES is categorized into three main groups depending on its power conditioning system, namely, the thyristor-based SMES, voltage-source- converter-based SMES, and current-source-converter-based SMES. An extensive bibliography is presented on the applications of these three types of SMES. Also, a comparison is made among these three types of SMES. This study provides a basic guideline to investigate further technological development and new applications of SMES, and thus benefits the readers, researchers, engineers, and academicians who deal with the research works in the area of SMES.

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An Overview of SMES Applications in Power and Energy Systems

Utilization of renewable energy are coming up from view points of environmental conservation and depletion of fossil fuel. However, the generated power from renewable energies is always fluctuating due to environmental status. Energy storage system is indispensable to compensate these fluctuating components. Energy capacitor system (ECaSS) connected an electric double-layer capacitor (EDLC) with power-electronics devices is useful for the compensation of fluctuating power since one is capable of controlling both active and reactive power simultaneously. This paper proposes the current-source ECaSS (CS-ECS), which consists of EDLC, bi-directional DC-DC converter, and current-source inverter. We have presented the control system for the active/reactive power control of CS-ECS, and have shown the effectiveness of CS-ECS through computer simulations for case of wind power generation system.

Output levelling of renewable energy by electric double-layer capacitor applied for energy storage system

The THz-radiation power from bulk InAs irradiated with femtosecond optical pulses is significantly enhanced and reaches 650 μW in a 1.7-T magnetic field with 1.5-W excitation power. The THz-radiation power is related almost quadratically both to the magnetic field and excitation laser power. We have also found that the power of the THz-radiation from an InAs sample in a magnetic field is over one order of magnitude higher than that from GaAs. Additionally, a dramatic change of ellipticity is observed, and the spectra of the horizontal and vertical polarization components are found to differ.

High average-power THz radiation from femtosecond laser-irradiated InAs in a magnetic field and its elliptical polarization characteristics

Multi-Parallel Configuration of a Current Source AC/DC Ccnverter with Energy Recovery Snubber Circuits

Stabilization of hydroelectric power system with long distance power transmission by using superconducting magnetic energy storage (SMES)

The quench current of a superconducting coil wound with a multifilamentary superconducting wire for 50-60 Hz use was measured for various frequencies by using a variable-voltage variable-frequency power supply composed of a cycloconverter or an inverter circuit to investigate characteristics of the superconducting AC coil and solve the current degradation problem. The test coil was wound by using wire containing no copper. Because of the instability of the wire, the effect of wire motion was observed, and quench current of the coil varied significantly. Generally, superconducting wires for AC use are unstable because the copper content of the wire is lower than for wires for DC or pulse use. From experimental results, it has become clear that a fixing method for wires to a bobbin keeping a good cooling condition is the key to solving the current degradation problem. >

http://ieeexplore.ieee.org/iel4/77/6032/00233486.pdf

Experimental study on quench current of superconducting coils for 50-60 Hz use

Temperature dependence of the transmittance of YBa/sub 2/Cu/sub 3/O/sub 7/ films on MgO substrates has been measured in the frequency range of 75-110 GHz. The transmittance was analyzed by taking account of the multiple reflection in the YBa/sub 2/Cu/sub 3/O/sub 7/ and MgO layers. Linear increase of the transmittance with temperature in the normal phase was explained by the Drude model, in which parameters (plasma frequency, relaxation time) obtained from the far-infrared measurements were used. The transmittance below T/sub c/ was analyzed by using the two-fluid model. Less steep increase of the transmittance above 50 K in the superconducting phase indicates that considerable amount of normal carriers exist even at temperatures sufficiently below T/sub c/. >

Yoshishige Murakami

Papers

Multi-Parallel Configuration of a Current Source AC/DC Ccnverter with Energy Recovery Snubber Circuits

Stabilization of hydroelectric power system with long distance power transmission by using superconducting magnetic energy storage (SMES)

Experimental study on quench current of superconducting coils for 50-60 Hz use

Transmittance of YBa/sub 2/Cu/sub 3/O/sub 7/ thin films in the millimeter wave region

Operating Characteristics of a Superconducting Transformer Connected in Parallel with a Conventional Transformer