The application of superconducting fault current limiters (SCFCLs) in power systems is very attractive because SCFCLs offer superior technical performance in comparison to conventional devices to limit fault currents. Negligible impedance at normal conditions, fast and effective current limitation within the first current rise and repetitive operation with fast and automatic recovery are the main attributes for SCFCLs. In recent years there has been a significant progress in the research and development (R&D) of SCFCLs. This paper gives an extended review of different SCFCL concepts, SCFCL applications and the R&D status. Within the first part of this paper the most important SCFCLS and, to a limited extent, non-superconducting fault current limiter (FCL) concepts are explained and compared. The second part reviews interesting SCFCL applications at the distribution and transmission voltage level and the third part shows in detail the R&D status. It can be summarized that SCFCLs are, at present, not commercially available but several successful field tests demonstrated the technical feasibility of SCFCLs. First distribution level applications are expected soon. Considerable economical and technical benefits can be achieved by applying SCFCLs at the distribution and transmission voltage level.

https://iopscience.iop.org/article/10.1088/0953-2048/20/3/R01/pdf

High-temperature superconductor fault current limiters: concepts, applications, and development status

Events in the power utility industry, such as deregulation, demands for better power quality and reliability, the advent of high temperature superconductivity, and the push to use technology to realize greater profits, have renewed interest in fault current limiters (FCL). Superconducting FCLs will become very important as the deregulation environment takes hold and utilities seek more efficient and cost-effective methods to couple grids, improve power quality, and delay expensive upgrades. The working principle and progress of superconducting FCLs is discussed in this article.

Superconducting fault current limiters

The development of superconducting systems for electric power is driven by the promise of improved efficiency, smaller size, and reduced weight as compared to existing technologies and by the possibility of new applications. Superconducting power components can also contribute to improved power quality and increased system reliability. This paper addresses historical developments and technology status of four superconducting power applications: cables, superconducting magnetic energy storage (SMES), fault-current limiters, and transformers. Today, SMES is the only fully functional superconducting system and it has seen only limited use at grid power levels. A few model or demonstration units exist for each of the other three applications. Superconductivity faces several hurdles on the path to widespread use. Perhaps the most important is the need for operating voltages of 100 kV or more. Though progress in this and other areas has been rapid, considerable development is needed before superconducting devices perform reliably in the utility environment. As a result, today, most initial installations are aimed at niche applications and will be installed where space is limited, where power demands are increasing over existing corridors, and/or where initial development costs can be offset by enhanced power grid performance.

Electric power applications of superconductivity

Superconducting fault current limiters (SCFCL) offer an attractive means to limit short-circuit currents in power systems. Comparisons of available HTS material led to the derision to investigate melt cast processed (MCP) BSCCO and melt textured polycrystalline YBCO for use in resistive SCFCLs. As a great length of a superconductor per unit element is preferred, the BSCCO samples are shaped as bifilar coils prepared from tubes and the YBCO samples are manufactured in a meander shaped geometry. Test results concerning contact resistances, E-J curves, AC losses as well as the quench behaviour of the samples are presented. The experiments reveal the requirement of a high material homogeneity as the main challenge.

Investigation of high-Tc bulk material for its use in resistive superconducting fault current limiters

A 15 kV class high temperature superconducting fault current limiter was developed as part of a Department of Energy Superconductivity Partnership Initiative (SPI) Phase II effort. This is an inductive/electronic fault current limiter (FCL) that can double as a fast sub-cycle solid state breaker. The said device was shipped to Southern California Edison (SCE) Center Substation at Norwalk, CA from General Atomics on June 15, 1999. Preliminary high voltage and high current testing was conducted. The pre-commercial FCL unit houses three of the world's largest Bi-2223 coils (solenoids each with an outside diameter of 1 m and a coil length of 0.75 m), collaborated by GA and IGC. These coils will operate at 35 K and be able to carry a continuous DC current of 2000 A as well as an AC pulsed current of 9000 A. Detailed specification of the FCL device and a brief description of its various subsystems will be given. Finally, test results at Center Substation are summarized and future work outlined. This Phase II FCL device is important as it has the potential to become the first major commercial product for HTS power utility application.

Design and development of a 15 kV, 20 kA HTS fault current limiter

Three large high temperature superconducting coils were used in the 15 kV class fault current limiter (FCL), designed and fabricated as part of a Phase II US DoE Superconductivity Partnership Program. Each of these solenoids measures 1.0 m in diameter and 0.75 m long. Each coil is designed to carry 2000 Adc and withstand an AC ripple of 16 A at 120 Hz. Each coil is wound from 15 km of Bi-2223 silver tapes and has an inductance of 4 mH. These coils were co-designed by General Atomics (GA) and Intermagnetics General Corporation (IGC) and constructed at the latter. GA provided the cryogenics and auxiliary components for the overall cryomagnetic assembly. Each coil is cooled by three cryocoolers and the designed operating temperature is 35 K. This paper presents the design specification of these coils. A brief description of the cryogenic and auxiliary setup is given and results from the thermal and electrical testing, that took place at General Atomics from April 13 to May 20, 1999, are presented.

Testing of the world's largest Bi-2223 high temperature superconducting coil

http://ieeexplore.ieee.org/iel5/5308791/5309530/05309579.pdf

D. Morris

Papers

Design and development of a 15 kV, 20 kA HTS fault current limiter

Testing of the world's largest Bi-2223 high temperature superconducting coil

Some uses of the oscillograph