Fengshun Jiao

Techno-Economic Evaluation of a Novel Flux-Coupling Type Superconducting Fault Current Limiter

Superconducting fault current limiters (SFCLs) offer a solution to control and suppress fault current levels on utility distribution and transmission networks, and are believed to be one of the most exciting applications of superconductors in power systems. Consequently, the various types of SFCLs have been developed in many countries. But, there is a very long way for SFCLs from prototypes or paper concepts to the practical applications and commercialization because of many unsolved problems. In this paper, a novel flux-coupling type SFCL is presented. This SFCL is composed of two superconducting windings and a controllable switch. In order to validate its fault current limiting performance, a simulation for the operation of this kind of SFCL in a modeling power system has been done. The simulation results show that it is feasible technically. Based on that, the economic feasibility by introducing a flux-coupling SFCL into the high voltage grid is estimated. Finally, the optimal locations for SFCLs are proposed.

Energy Function Based SMES Controller for Transient Stability Enhancement

Superconducting Magnetic Energy Storage (SMES) which is characterized by its highly efficient energy storage, quick response, and power controllability, is expected to contribute to the transient stability of power system. The energy function approach is frequently used as a convenient way to control or analyse the power system. Based on the dynamic characteristic of SMES, the interaction between the SMES and the power system is analysed. According to the additional damping provided by SMES, energy function based control strategy is designed to improve the transient stability of power system. Then, the functional range of the SMES power control is analysed, which can be utilized to optimize the allocation of SMES in power system. Simulation tests are performed to evaluate the performance of the proposed energy function based control method.

Design of a 10 MJ HTS Superconducting Magnetic Energy Storage Magnet

This paper outlines a systematic procedure for the design of a toroidal magnet for Superconducting Magnetic Energy Storage System and presents the optimum design for a 10 MJ class high temperature superconductor (HTS) magnet. The main magnetic component which influences the maximum critical current was investigated. Stray field and operating current needed in a toroidal magnet with different number of elemental coils were compared too. Based on above analysis, both electromagnetic and mechanical design objects were considered when optimizing the volume of HTS Superconducting magnet with optimal number of toroidal elements with Finite Element Method. Parameter surveys of the magnetic fields and electromagnetic stress applied to the HTS magnets were carried out and a suitable magnet dimension with low inductance and high current was studied. The results verify that the double pancake type is more favorable for actual design and operation.

Development of a Movable HTS SMES System

A 600-V/150-kJ/100-kW conduction-cooled high-temperature superconducting (HTS) magnetic energy storage (SMES) system is developed. In this paper, the configuration of the HTS SMES is introduced. The magnet is a solenoid type, which uses two kinds of HTS tapes, and cooled to about 20 K. A series of laboratory experiments and field tests are carried out to evaluate the performance of the SMES system, including the current-carrying ability of a magnet, the active and reactive power exchange capability between the SMES and an alternating-current power system, power oscillation damping, the improving electrical energy quality, etc. The results show that the SMES system meets the design requirements and can maintain a long-term stable operation in a power system.

The Conceptual Design of Hybrid High Temperature Superconducting Magnet

The anisotropy of electromagnetic performance of high temperature superconducting (HTS) tapes is significant. The performance of BSCCO and YBCO, both of which have been employed in industry already, is varied when they stand different orientations of magnetic field. In HTS magnet design, adopting optimization can directly affect the performance of magnet and the amount of the tapes employed in the magnet, namely affects the economy of magnets. Considering both the measurement results of magnetic field characteristics of the HTS tapes in the critical current and the technical requirement of the diminutive superconductor magnetic energy system(SMES) which is laboratory scale, this paper puts forward the technical scheme of making hybrid HTS magnet which employs both BSCCO and YBCO, then fulfills the optimization design of the hybrid HTS magnet by means of finite element analysis, which considers the performance of energy storing as constraint condition and the economical efficiency as destination. This paper verifies the superiority of employing two types of tape to make a HTS magnet.

Electromagnetic and Thermal Design of a Conduction-Cooling 150 kJ/100 kW Hybrid SMES System

Owing to the application of high-temperature superconductor (HTS) tapes, superconducting magnetic energy storage (SMES) magnets can be economical to run at temperatures around 20 K. The conduction-cooled SMES magnet has become a reality with the rapid development of cryocooler technology. In China, a 150 kJ/100 kW conduction-cooled SMES employed for power quality is now being developed by Huazhong University of Science and Technology (HUST) and Hubei Electric Power Company (HBEPC). In electromagnetic design, a hybrid structure that uses two kinds of HTS tapes is employed to increase the critical current, Ic, of the SMES magnet. This paper presents an electromagnetic and thermal design of the conduction-cooling system for the magnet. The relationship between Ic and temperature is analyzed, and the target parameters of the conduction cooling system are finalized. The design scheme of the cooling system is developed by analyzing thermal conductivity characteristics of HTS double-pancakes, thermal loads, thermal resistance, and cooling demands. Finite element analysis results show that the design scheme meets the requirements well in static conditions.

Design of a Termination for the HTS Power Cable

A 1-km, cold dielectric, high-Tc superconducting (HTS) power cable is being planned in China. The rated voltage and current are 110 kV and 2 kA, respectively. The termination, which connects the superconducting cable conductors at cryogenic temperature to a power transmission line at room temperature and an external cooling system at ground potential, is one of the crucial parts of the superconducting cable system. In this paper, such a termination is designed, including the current lead, the electrical insulation, the condenser cone and the SC-NC joint.

Evaluation of Three Designs for a 35-kV Class Superconducting Reactor

With the expansion of the grid, continuous reactive power compensation is vital for efficient operation of long transmission power lines or cables. Yunnan Electric Power Grid Company is planning to develop superconducting controllable reactors for 500-kV long-distance ac transmission lines. As the second stage of the development plan, a 35-kV class superconducting reactor will be designed and verified by experiments. In this paper, three design proposals, including the racetrack-core type, the three-limb-core type, and the D-core type, for the 35-kV class superconducting reactor are given. Then, their technical and economic feasibility is evaluated. This paper shows that the racetrack-core saturable reactor is a good choice from a technical and economic point of view.