Advanced Superconducting Power Conditioning System Research Articles

Demonstration of 10 KJ-Capacity Energy Storage Coil Made of MgB2 With Liquid Hydrogen Indirect Cooling

10 kJ-Capacity Energy Storage Coil Made of MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> proposed in the Advanced Superconducting Power Conditioning System (ASPCS) was fabricated, and an electric current test was conducted with indirect liquid hydrogen cooling. This coil consists of three DP (double pancake) coils with an inner diameter of 400 mm and an outer diameter of 606 mm. The first DP was manufactured by the W&R (Wind and Reacted), and second and third DPs were manufactured by the R&W (React and Wind). A thermosiphon system is used for cooling the coils, in which the coolant is circulate without pump. For energization, several DC excitation and AC excitation tests were carried out with liquid hydrogen, and the rated current of 600 A was successfully achieved. The evaluation of both DC and AC losses were also performed, indicating needs to reduce the losses for stable operation under the indirect cooling conditions.

Demonstration and thermal equilibrium analysis of a 10 kJ capacity energy storage coil made of MgB2 with liquid hydrogen indirect cooling

We have demonstrated an advanced superconducting power conditioning system, in which a superconducting magnetic energy storage (SMES) device, a generator based on a fuel cell (FC), and an electrolyzer are used to compensate for electricity fluctuations over a wide frequency range, combined with a liquid hydrogen storage system to both cool the SMES and provide pure hydrogen gas to the FC and other gas-dependent systems. To manufacture the coils for the SMES, we used MgB2, whose critical temperature is below the boiling temperature of hydrogen. We developed a 10 kJ SMES coil system indirectly cooled by liquid hydrogen using thermosyphon passive heat exchange to isolate the flammable hydrogen from the electrical components. We performed a successful demonstration of this system for both DC and AC currents ramped at different rates. In the present study, we use computer simulations involving heat balance equations to evaluate the stability of the system. The results obtained are expected to lead to the design of future large-capacity energy storage systems, such as the MJ class, which offer comparable performance to conventional NbTi SMES devices.

Theoretical and experimental investigation of R&W and W&R SMES coils wound with large-scale MgB2 Rutherford cables operated around liquid hydrogen temperature

We have developed the system called Advanced Superconducting Power Conditioning System (ASPCS) composed of a Superconducting Magnetic Energy Storage (SMES), a fuel cell and a water electrolyzer for effective use of renewable energy such as wind and solar power generation. We have been investigating about the SMES coil using the large-scale Rutherford-type conductors made of commercially-available MgB2 wires. Due to strain sensitivity even before heat treatment for MgB2 production, the design for large-scale Rutherford cables both in the wind and react (W&R) method, and the react and wind (R&W) method applied to coil fabrication has to be done cautiously to prevent the degradation of the IC by the optimizing design parameters such as the twist pitch and the cable compaction. Especially for the R&W method using heat-treated wires, other factors like handling during the coil production process which affect the conductor and coil IC should be also considered. To evaluate the applied strains during the manufacturing process, we conducted theoretical investigation on the strains applied to individual filaments caused by wire-bending. We developed a test coil designed for the R&W method based on analyzing those factors. Furthermore, we measured the coil IC-B-T characteristics and compared to those of other test coils made by the W&R method.

Stability Analysis of MgB2 Coils for SMES Application Consisting of Large-Scale Rutherford Cables

MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wires have been provided by several manufacturers, showing enough critical current (Ic) for practical applications in relatively low-field. Because the MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> has critical temperature above boiling temperature of hydrogen, dc power distribution system with low carbon emission using MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> superconducting magnetic energy storage (SMES), named advanced superconducting power conditioning system has been proposed. For the system, the MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> coil production technology obtaining 30 kJ stored energy the investigation about the SMES coil consists of 600 A, 1.7-T Rutherford-type conductors made of commercially-available MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wires. Due to strain sensitivity before/after heat treatment for MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> production, the proper designs of the large-scale twisted conductors both in wind and react, react and wind methods are needed, choosing optimized twist pitches and cable compaction factors. To demonstrate the SMES coil performance, we have been carried out the test campaign of conductors and small prototype coils in various temperature and background field conditions. These results are used for a computer simulation for estimating full size double pancake coil performance of the system, based on the non-steady state heat conduction analysis. The calculated result seems to be a good tool for predicting coil performance for the large capacity energy storage operation.

Superconducting Properties of a Prototype Pancake Coil Using a MgB2 Rutherford-Type Stranded Conductor

A prototype pancake coil using a MgB2 Rutherford-type stranded conductor for superconducting magnetic energy storage (SMES) proposed in the Advanced Superconducting Power Conditioning System was fabricated and evaluated. The conductor consisted of a CuNi former, eight MgB2 wires and four Cu wires, with a twist pitch of 51 mm, and a pancake coil of 200 mm inner diameter, 269 mm outer diameter, and 7 mm thickness was manufactured using the wind-and-react method. The prototype coil was cooled by conduction cooling using refrigerators and the critical current under 1.5 T at 25 K exceeded 700 A. These measurements suggest that several kJ class MgB 2 SMES using MgB2 stranded conductors could be designed appropriately in terms of the bending strain.

Performance of a 10-kJ SMES model cooled by liquid hydrogen thermo-siphon flow for ASPCS study

We propose a new electrical power storage and stabilization system, called an Advanced Superconducting Power Conditioning System (ASPCS), which consists of superconducting magnetic energy storage (SMES) and hydrogen energy storage, converged on a liquid hydrogen station for fuel cell vehicles. A small 10- kJ SMES system, in which a BSCCO coil cooled by liquid hydrogen was installed, was developed to create an experimental model of an ASPCS. The SMES coil is conductively cooled by liquid hydrogen flow through a thermo-siphon line under a liquid hydrogen buffer tank. After fabrication of the system, cooldown tests were carried out using liquid hydrogen. The SMES coil was successfully charged up to a nominal current of 200 A. An eddy current loss, which was mainly induced in pure aluminum plates pasted onto each pancake coils for conduction cooling, was also measured.

Experimental Research on Compensation for Power Fluctuation of the Renewable Energy Using the SMES Under the State-of-Current Feedback Control

Power generation by renewable resources that are environment friendly has been attractive lately. However, it is a big problem that the output fluctuation from the renewable energy sources causes instability to the power network when they are directly connected to the utility grid. Although a power storage system is effective for compensating for the output fluctuation, this electric power storage system must have large capacity and quick response. We proposed an advanced superconducting power conditioning system (ASPCS) composed of two kinds of power storage systems. In this paper, we experimentally verified the validity of the compensating system for fluctuating output power using a superconducting magnetic energy storage and an electronic load instead of an electrolyzer. It was demonstrated that the ASPCS was effective for compensating for the output fluctuation of the renewable energy.

Eddy Current Loss Induced in Aluminum Thermal Conduction Strips for ASPCS Coils Indirectly Cooled by Liquid Hydrogen through Thermo-siphon System

To promote renewable energy sources, we proposed a new system called the Advanced Superconducting Power Conditioning System (ASPCS), which consists of Superconducting Magnetic Energy Storage-system (SMES), Electrolyzer, and Fuel Cell, and is also combined with a liquid hydrogen station for vehicles. The SMES plays a role to compensate the fast fluctuations generated by the renewable energies. In case of the ASPCS with a capacity of 5 MW, we designed the 50 MJ-class SMES composed of 4 solenoid coils. The winding of the solenoid coils is double pancake and a basic coil is 2 m in diameter and 0.5 m in height. Each SMES coil is wound with MgB2 conductor and indirectly cooled at 20K by liquid hydrogen flowing through a thermo-siphon cooling system. Pure aluminum strips are inserted between the double-pancake coils and the pure aluminum plates gathering the strips lead to liquid hydrogen pipes. This scheme enables the strips and the plates to transfer the heat load in the coils to the cooling pipes and keep the coils at low temperature. On the other hand, we must consider that the strips generate eddy current loss which is strongly affected by a width of the strips. At the same time as the primary study of the SMES coils, we experimented on the thermo-siphon cooling system and investigated the relationship between the heat load and the heat extraction ability of the cooling system. The experiments showed that the cooling system could proficiently function. The estimation of eddy current loss from the particular cooling aluminum strips for the SMES in the ASPCS is reported with the results of the thermo-siphon driving experiment.

新エネルギーシステム構築のための液体水素冷却MgB2 超伝導線を用いた電力変換システムの研究開発

新エネルギーシステム構築のための液体水素冷却MgB₂超伝導線を用いた電力変換システムの研究開発

Design Study of $\hbox{MgB}_{2}$ SMES Coil for Effective Use of Renewable Energy

In order to use effectively renewable energy sources such as wind and photovoltaic power generations, we propose a new system, called Advanced Superconducting Power Conditioning System (ASPCS), that is composed of superconducting magnetic energy storage (SMES), fuel cell-electrolyzer (FC-EL), hydrogen storage, dc/dc and dc/ac converters, and controller. The new system compensates the fluctuating electric power generations with SMES having characteristics of quick response and large I/O power and with hydrogen energy having characteristics of large storage capacity. The ASPCS will be combined with a liquid hydrogen station for FC vehicles. The SMES is a key component of the ASPCS to compensate the fast fluctuations of the renewable energy generations that cannot be compensated by prediction using the Kalman filtering method. The design study of the 50 MJ SMES coil was performed with an MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> conductor to be operated at 5 T maximum and 20 K by using liquid hydrogen of the FCV stations. The stability and ac losses of the coil were estimated in this study.

Design study of the cooling scheme for SMES system in ASPCS by using liquid hydrogen

From the point of view of environment and energy problems, the renewable energies have been attracting attention. However, fluctuating power generation by the renewable energies affects the stability of the power network. Thus, we propose a new electric power storage and stabilization system, Advanced Superconducting Power Conditioning System (ASPCS), in which a Superconducting Magnetic Energy Storage (SMES) and a hydrogen-energy-storage converge on a liquid hydrogen station for fuel cell vehicles. The ASPCS proposes that the SMES coils wound with MgB2 conductor are indirectly cooled by thermo-siphon circulation of liquid hydrogen to use its cooling capability. The conceptual design of cooling scheme of the ASPCS is presented.

Wind Power Forecasting using an Artificial Neural Network for ASPCS

In order to use effectively renewable energy sources, we propose a new system, called Advanced Superconducting Power Conditioning System (ASPCS) that is composed of Superconducting Magnetic Energy Storage (SMES), Fuel Cell-Electrolyzer (FC-EL), hydrogen storage and DC/DC and DC/AC converters in connection with a liquid hydrogen station for fuel cell vehicles. The ASPCS compensates the fluctuating electric power of renewable energy sources such as wind and photovoltaic power generations by means of the SMES having characteristics of quick response and large Input-Output power, and hydrogen energy with FC-EL having characteristics of moderate response and large storage capacity. The moderate fluctuated power of the renewable energy is compensated by a trend forecasting method with the Artificial Neural Network. In case of excess of the power generation by the renewable energy to demand it is converted to hydrogen with EL. In contrast, shortage of the electric power is made up with FC. The faster fluctuation power that cannot be compensated by the forecasting method is effectively compensated by SMES. In the ASPCS, the SMES coil with an MgB2 conductor is operated at 20 K by using liquid hydrogen supplied from a liquid hydrogen tank of the fuel cell vehicle station. The necessary storage capacity of SMES is estimated as 50 MJ to 100 MJ depending on the forecasting time for compensating fluctuation power of the rated wind power generation of 5.0 MW. As a safety case, a thermosiphon cooling system is used to cool indirectly the MgB2 SMES coil by thermal conduction. In this paper, a trend forecasting result of output power of a wind power generation and the estimated storage capacity of SMES are reported.

Application of SMES and Fuel Cell System Combined With Liquid Hydrogen Vehicle Station to Renewable Energy Control

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.

Design Study of SMES System Cooled by Thermo-Siphon With Liquid Hydrogen for Effective use of Renewable Energy

In order to use effectively renewable energy sources, we propose a new system, called Advanced Superconducting Power Conditioning System (ASPCS), that is composed of SMES and Fuel Cell-Electrolyzer (FC-EL) in connection with a liquid hydrogen station for vehicles. The new system will compensate the fluctuating renewable energy sources with SMES having characteristics of quick response and large I/O power, and with FC-EL having characteristics of moderate response and large storage capacity. The SMES coil with an MgB2 conductor operated at 20 K is cooled with a thermo-siphon cooling system by using cryogen from the liquid hydrogen station. The necessary minimum storage capacity of SMES is estimated as 50 MJ for compensating output power of 1 MW. A four-pole SMES coil is designed by using stranded cable concept. The design study of the SMES coil composed of the MgB2 conductor and the thermo-siphon cooling system is reported.

Advanced Superconducting Power Conditioning System for Effective Use of Renewable Energy

Advanced Superconducting Power Conditioning System for Effective Use of Renewable Energy

Conceptual design of MgB2 coil for the 100 MJ SMES of advanced superconducting power conditioning system (ASPCS)

Abstract In order to reduce global carbon-dioxide in the world, we propose an Advanced Superconducting Power Conditioning System (ASPCS) which is composed of 5 MW renewable energy resources and 1 MW hybrid storage system. The hybrid storage system is composed of FC-H2-EL and SMES which is installed adjacent to a LH2 station for vehicles. Since the SMES can be operated at 20 K which is a saturated temperature of LH2, we can use MgB2 superconductors. In the ASPCS, 100 MJ storage capacities of the SMES should be required. This paper focuses on studies into a conceptual design of SMES toroidal coil composed of the MgB2 and indirectly cooled by LH2.

Advanced superconducting power conditioning system with SMES for effective use of renewable energy

Since it is an urgent issue to reduce the global Carbon-dioxide in the world, renewable energy should be supplied as a large amount of the electric power. However, if a large amount of fluctuating renewable energy becomes more than adjustable amount of a utility grid capacity, instabilities such as frequency deviation might occur. We propose a system that is composed of SMES and FC-H2-Electrolyzer and also installed adjacent to Liquid Hydrogen station to cool down the SMES. Since the SMES has potentials of quick response and large I/O power, and Fuel Cell has potentials of slow response and steady power supplied from a large amount of hydrogen, we combine both storage devices and apply them to suppress the fluctuating power. We convert the fluctuating power to the constant power by using a developed prediction technology of Kalman filter to predict a trend of the fluctuating power. While the trend power should be supplied by FC or absorbed by the electrolyzer to produce hydrogen, the power difference between the renewable power and the trend power should be stored by the SMES. We simulate the power balance and analyze the required SMES capacity, design the concept of the SMES, and propose an operation algorithm for the SMES to estimate the electric efficiency of the system. It is found that the electric efficiency of the ASPCS can become greater than that of a pumped hydro-machine.