Zhiqin Zhu

Development and Test of 10.5 kV/1.5 kA HTS Fault Current Limiter

Superconducting Fault Current Limiter (SFCL) is an attractive appliance for modern electrical power system. A 10.5kV/1.5 kA three-phase HTS fault current limiter was developed by IEE, CAS. This improved rectifier-type SFCL with HTS coil of 6.25 mH is going on a demonstrated long-term reliable operation in a real 10.5 kV substation located in Hunan, China. In a three-phase-to-ground short circuit test of grid, the prospective fault current of 3.5 kA was limited to 635 A at the pre-setup short-circuit point successfully

Design of a 380 m DC HTS Power Cable

High temperature superconducting (HTS) power cable is an effective power transmission utility with large capacity, high efficiency, and low loss, especially in DC power transmission. This paper describes the design of a 380 m HTS power cable with rated current of 10 kA for an aluminum electrolysis enterprise. The power cable connects the rectifier at a substation at one end with the bus bar of an aluminum electrolysis plant at the other end at Henan Zhongfu Industrial Co. LTD. The power cable will be energized in late of 2010. The design of the cable conductor, cryogenic envelope, termination, refrigeration, and online monitoring system of the 380 m HTS power cable are discussed in this paper.

Design, Fabrication, and Tests of Three HTS Coils for a Model Fault Current Limiter

The design, fabrication and tests of three high temperature superconductor (HTS) coils for a rectifier-type model fault current limiter (FCL) were presented. The field distributions in the coil were numerically analysed by FEM. Based on the field distributions and the strong anisotropic characteristics of Bi2223/Ag tape, the HTS coils were designed and fabricated. The inner diameter and the height of the coils were 80 mm and 94 mm, respectively. Each of the coils consisted of 8 double pancakes. Every double pancake consisted of 103 turns with 35 meters of Bi-2223/Ag tape. After the characteristics of the coils were tested in liquid nitrogen, three of the coils were assembled in their nonmetallic-material cryostats and works with the model FCL.

Testing and Demonstration of a 10-kA HTS DC Power Cable

A 10-kA/360-m high-temperature superconducting (HTS) dc power cable has been developed and installed in 2012 in central China. The cable is connecting a rectifier at a substation to a bus bar of an aluminum electrolysis plant. Before operating in the power grid, a series of testing on the performance of the cable was conducted. The testing results show that the performance meets the operational requirements and that the critical current of the cable exceeds 12.5 kA. The 10-kA HTS cable was successfully energized at the Henan Zhongfu Industrial Company Ltd., Gongyi, China, on September 26, 2012. Since then, the cable has been stably and reliably supplying power for the companys aluminum electrolyzing plant.

Development and Demonstration of a 1 MJ High-Tc SMES

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 worlds 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.

The Construction Progress of a High-Tc Superconducting Power Substation in China

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.

The Electromagnetic Analysis and Structural Design of a 1 MJ HTS Magnet for SMES

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.

Overview and Development Progress of a 1-MVA/1-MJ Superconducting Fault Current Limiter-Magnetic Energy Storage System

A 1-MVA/1-MJ superconducting fault current limiter-magnetic energy storage system (SFCL-MES) is under development. The SFCL-MES is used to enhance the low voltage ride through capability and smooth the output power of the wind farm. The SFCL-MES is composed of four major components: a power controller, a superconducting coil, a cryogenic refrigeration system, and a monitoring system. This paper gives an overview of the SFCL-MES and briefly introduces the design and development progress of the four major components. Simulation results with the design parameters are also presented to evaluate the performance of the SFCL-MES.

Winding Design and Electromagnetic Analysis for a 1250-kVA HTS Transformer

Because high-temperature superconducting (HTS) coils possess low-resistivity, large-current-carrying, and state transition characteristics, the design of HTS transformers is much different from that of conventional ones. The general design of 10.5-kV/1250-kVA HTS transformer is given first. In the electromagnetic design of the 1250-kVA HTS transformer windings via field-circuit coupling simulation, the influence of leakage magnetic field on the critical current of tapes and the circulating current of parallel branches was considered. Moreover, the transient stability of transformer windings combined with superconducting fault current limiter in the HTS power substation is discussed. Based on electromagnetic analysis, the primary and the secondary windings are constructed, and a special transposed method for double pancakes wound with four parallel tapes is proposed. Finally, the current-carrying ability of the primary and the secondary windings is tested in 77 K. Their critical currents are higher than 200 and 3200 A, respectively, which is enough in rated operating condition.

Development of solenoid and double pancake windings for a three-phase 26 kVA HTS transformer

We prepared 6 coils from the stainless steel-enforced multifilamentary Bi2223/Ag tapes and studied their electromagnetic behavior for a three-phase 26 kVA (400 V/16 V, 37.5 A/937.5 A) transformer. The primary windings were solenoid coils consisted of 4 helically wound layers, and the secondary windings were consisted of 24 double pancakes connected in parallel with 3 layers, the strand of 6 windings was consisted of two parallel transposed multifilamentary tapes. A numerical analysis has been developed to predict the DC and AC behavior of the coils based on measurements of short samples and tested coils at 77 K. A comparison is made between the experiment and model calculation.