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With the increase of electricity demand and the rapid development of renewable energy generation, it is becoming more and more important to ensure the safety and stability of power grid, where a superconducting fault current limiter (SFCL) could play an important role. In recent years, a lot of research work has been done in China on the application of high temperature superconducting (HTS) power technology, especially in the aspects of superconducting fault current limiting technology, superconducting fault current limiting-breaking technology, superconducting fault current limiting- magnetic energy storage technology, and superconducting fault current limiting transformer technology. A number of demonstration projects on SFCL were also conducted. In this paper, the research progress of HTS fault current limiters (both AC and DC) in China in recent years is introduced, including the completed projects and the on-going work. The possible application direction of SFCL in the future is proposed. [ABSTRACT FROM AUTHOR]

Abstract: Single‐crystal diamonds are successfully synthesized using microwave plasma chemical vapor deposition. A smooth and flat single‐crystal surface is obtained by optimizing the size relationship between the seed substrate and the square hole of the shielding ring. When the sample grows higher than the polycrystalline diamond on the molybdenum holder, the surface becomes uneven. The polarization characteristics of two kinds of chemical vapor deposition (CVD) layers are compared between flat and uneven surfaces. Abnormal high‐order birefringence occurs in both morphologies, which is related to the dislocation density in the CVD layers. The higher the dislocation density of the sample, the more obvious the high‐order anomalous birefringence. High‐pressure high‐temperature seed substrates have obvious defects, such as dislocations, stacking faults, and boundaries of the growth sector, and these defects are mostly distributed at the edge of seed substrates. When the diamond surface demonstrates an edge‐to‐center morphology, the dislocations in the seed substrate, interface‐induced dislocations, and dislocations formed in the growth layer begin to converge toward the central region of the CVD layer, which results in a smaller area of low stress in the center of the CVD layer. High dislocation density causes the crystal to have a mosaic structure and orientation deviation. [ABSTRACT FROM AUTHOR]

A superconducting magnetic energy storage system (SMES), with stored energy of 1 MJ and compensation power of 0.5 MVA, has been developed successfully, and now is operating at the world's first superconducting power substation at Baiyin National High-Tech Industrial Development Zone, Gansu Province, China. The SMES employs a high Tc superconducting magnet, which consists of 44 pancakes, operates at 4.2 K in liquid helium, and is cooled down by 4 G-M cryo-coolers. The SMES connects to a 10.5 kV power grid by the use of a power conversion system. Since 16 February, 2011, the SMES has been operating reliably, and providing good-quality power for three companies. [ABSTRACT FROM PUBLISHER]

A 0.5 MVA/1 MJ superconducting magnetic energy storage system (SMES) has been installed in a superconducting power substation. The SMES is designed to compensate active power fluctuations, current harmonics and reactive power of the downstream load. The system configurations and control strategies are described. Experimental and field test results show that the proposed SMES can effectively improve the power quality of the power system. [ABSTRACT FROM PUBLISHER]

An HTS magnet was designed for the 1 MJ/0.5 MVA SMES with Bi2223/Ag tapes. According to the design, it consists of 44 double pancakes with an inductance of 6.28 H, and the rated operating current is 565 A, the maximum magnetic field is up to 5.72 T. In this paper, the insulation of the tapes and the magnet, the fabrication and tests of the 44 double pancakes, the joints among double pancakes and the assemblage of the magnet are described in detail. And then, the fundamental performances testing of the magnet were carried out at liquid nitrogen and helium, respectively. With zero helium vaporization, the 1 MJ HTS magnet was dip in liquid helium and cooled with four G-M cryocoolers. After the whole 1 MJ/0.5 MVA SMES were field installed and tested, it had been put into operation since Feb. 16 of 2011 at a 10.5 kV superconducting power substation locating in Baiyin, Gansu Province of China. [ABSTRACT FROM PUBLISHER]

The new energy revolution which will be dominated by renewable energy will need to develop a corresponding new power grid. Based on the characteristics of renewable energy resources, and the stability problem of AC network, it was proposed that the DC-based transmission grid should be developed in the future. The high Tc Superconducting (HTS) power cable will be a competitive candidate for large-capacity power transmission of renewable energy. In this paper, the progress of the development of a 360 m/10 kA HTS DC power cable is presented, and the prospects of HTS cable is discussed. [ABSTRACT FROM PUBLISHER]

With the increasing depletion of fossil fuels and growing environmental pressure, the mankind has got known the need to vigorously develop the renewable energy and the energy-saving technology. The high Tc superconducting (HTS) power technology will be very helpful to enhance the stability, reliability, and efficiency and transmission capacity of the power grid which would be dominated by the renewable energy. In this paper, we will report the installation and operation of a 10 kV HTS power substation which includes a 75 m/1.5 kA HTS power cable, a 10 kV/1.5 kA HTS fault current limiter, a 1 MJ/0.5 MVA high Tc SMES and a 630 kVA/10 kV/0.4 kV HTS power transformer. [ABSTRACT FROM PUBLISHER]

It is expected that superconducting technologies will play an important role in the future smart grid, because the application of superconductor technologies in the power grid can decrease power losses, relieve overload, avoid higher levels of transmission voltage, increase power transmission capacity, and improve power quality and grid stability. In recent years, high temperature (high-Tc) superconducting power technologies have achieved remarkable progress. High temperature superconducting (HTS) power equipment, such as HTS power cables, HTS transformers, high-Tc superconducting fault current limiters (SFCL), and high-Tc superconducting magnetic energy storage devices (SMES) have been demonstrated in the power grids of many countries. With the development of HTS power equipment, the construction of a HTS power substation is ready. In China, a 10.5 kV HTS power substation is under construction in Baiyin city, Gansu province. The substation integrates a HTS power cable, a HTS transformer, a HTS fault current limiter, and a high-Tc SMES. All these HTS power devices, which were previously developed by the Institute of Electrical Engineering (IEE), Chinese Academy of Sciences (CAS), have been demonstrated to operate for a long time in the commercial power grid. In this paper, the design and constructing progress of the HTS substation are introduced in detail. [ABSTRACT FROM AUTHOR]

An HTS magnet was designed and fabricated for the 1 MJ/0.5 MVA SMES. It consists of 44 double pancakes with an inductance of 6.28 H, and the rated operating current is 565 A. In this paper, the electromagnetic analysis and the structural design of the magnet are presented. Because of the strong anisotropy of Bi2223/Ag tape, the field distribution can seriously affect the performances of the magnet. Its magnetic field distribution is analysed by means of finite element method (FEM). Similarly, the critical current (Ic) distribution of each turn in the magnet is also calculated. Based on the analyses and calculations, the structural design of the magnet for 1 MJ/0.5 MVA SMES is finished. In order to obtain a uniform current distribution between co-wound tapes in the same double pancake and among the parallel connected double pancakes, special methods are developed for the structural design. [ABSTRACT FROM AUTHOR]

Persistent current (PC) operating magnet with bore diameter of about 32 mm was design and developed based on multi- and mono-filament MgB2 wires. The magnet was in a multi-solenoid structure. One pilot coil was wound and joints were fabricated at both ends, connecting it to a superconducting switch for PC operation tests. The magnet was to demonstrate the high field and high temperature performance at different temperatures. Numerical and experimental results demonstrated a promising future of MgB2 wires in low cost magnetic resonance imaging (MRI) systems and high field scientific magnets. [ABSTRACT FROM AUTHOR]

High temperature superconducting (HTS) generator was promising in the wind power applications for its advantages in the weight, size and thermal stability against load fluctuations, especially in the “direct-driven” design. A 100 kW generator was proposed for the demonstration of the feasibility of using HTS in 10 MW wind turbine generators. The electromagnetic design and optimization of the rotor were done using finite element method (FEM). The excitation coil of the rotor was designed considering variable working conditions. According to the numerical results, a number of suggestions in the design and winding techniques of the superconducting rotor were proposed. [ABSTRACT FROM AUTHOR]

High temperature superconducting (HTS) cable is one of important apparatus in future smart-grid. Direct current (DC) HTS cable can provide secure and reliable transmission of electric power at the gigawatt level with several hundreds of kA and kV. Since the magnetic field of cable seriously degrades the critical current of HTS superconductor and then the current capacity, modern power converters often introduce alternating currents (AC) at other frequencies even filters reduce the magnitude of those ripple currents which resulting into ac loss since systems used to convert AC to direct current (DC) produce some current variations which are usually at frequencies of multiple power frequency. In order to reduce this loss, unlike the conventional uniform current design in AC HTS cable, a novel approach is proposed for minimizing the loss as small as possible by adjusting the inductive reactance of each layer so that the ratios of AC current amplitude to critical current are always same in layers. The magnetic field distribution and critical current are simulated by finite element method (FEM). The calculations show that the new approaches can reduce ac loss, improve efficiency, which are potential for DC current transmission HTS cable application. [ABSTRACT FROM AUTHOR]