Development Of Superconducting Fault Current Limiter Research Articles

Converter non‐blocking DC fault ride‐through and system fast restoration arrangements in R‐L SFCL‐equipped MMC‐M2TDC system

AbstractEquipping a DC‐type superconducting fault current limiter (SFCL) in a modular multilevel converter‐based multi‐terminal DC (MMC‐M2TDC) system has the potential to reorganize the protection control arrangements during the DC‐side short‐circuit fault. This paper introduces the converter non‐blocking operation and system fast restoration control of the SFCL MMC‐M2TDC with the DC‐side bipolar fault condition, as well as their feasibility verifications. Considering the characteristics of overdamping oscillation of DC voltage and the additional impedance effect of the new resistor‐inductor SFCL (R‐L SFCL), the unfaulty converter non‐blocking protection enables faulty segment isolation and DC fault ride through without unwanted active power interruption. The restoration control for smooth reconnection and fast recovery of the off‐grid converter station ensures the DC voltage rebuilding process and reduces the required period. To validate the above arrangements, the simulation is conducted upon the PSCAD/EMTDC corresponding to the three‐terminal R‐L SFCL MMC‐M2TDC system. Finally, the research routes for novel superconducting coil design, SFCL scheme design, and multi‐device cooperative strategy are discussed, all of which contribute to promoting the high‐quality development of SFCL in MMC‐M2TDC scenarios.

Application study of a high‐temperature superconducting fault current limiter for electric power system

AbstractUsing high‐temperature superconductors, a superconducting fault current limiter (SFCL) was fabricated and tested. The superconductor and a vacuum interrupter serving as a commutation switch were connected in parallel with a bypass coil. When a fault occurs and excessive current flows, the superconductor is first quenched and the current is transferred to the bypass coil because of the voltage drop of the superconductor. At the same time, since a magnetic field is generated by the current flowing in the bypass coil, the commutation switch is immediately driven by an electromagnetic repulsion plate connected to the driving rod of the vacuum interrupter (VI), and the superconductor is separated from this circuit. Using the test model, we were able to separate the superconductor from the circuit by the movement of the VI within a half current cycle and to transfer all current to the bypass coil. Since the operation of the commutation switch is included in the current limiting operation of this test model, it will be a useful circuit in the development of SFCL in the future. Moreover, since it can make the energy consumption of the superconductor small during the fault state due to the realization of a high‐speed switch with simple composition, the burden on the superconductor is reduced compared with the conventional resistive type of SFCL and it is considered that the flexibility of SFCL design is increased. Cooperation with a circuit breaker was also considered; trial calculations of the parameters and energy of operation were conducted and a discussion of the installation of the SFCL in an electric power system is presented. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(4): 20–29, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20265

High temperature superconducting fault current limiter development

A near term high-temperature superconductor (HTS) application is the fault current limiter (FCL). This paper describes the development and testing of a 2.4 kV, 2.2 kA(RMS) fault current, 150 A(RMS) continuous current, HTS FCL that uses a Bi-2223 Ag-based conductor. The Lockheed Martin team, which included Southern California Edison (SCE), American superconductor Corporation (ASC) and Los Alamos National Laboratory (LANL), completed in October 1995 a two year Phase I program. This unit has undergone a six-week extensive testing at SCE's Center Substation in Norwalk, California. The unit's capability and test results are presented. Plans for the construction of higher rating units including a phase II program are outlined. Descriptions of the underlying principle of a FCL and how it can benefit the power utility industry are also presented.

The current status of superconducting fault current limiter development

Demand for electric power in Japan has been steadily increasing in recent years.To meet this demand, power networks have been more robustly connected with a view to improving their reliability. However, this has been accompanied by a trend toward a greater incidence of fault currents in these power networks. If a fault current limiter is used to connect these systems, electric power utilities will be able to accommodate electric power through the superconducting limiter from a system with excess capacity to another system in which the available power is insufficient, while the limiter protects systems from the influence of faults in a system. The authors have developed a 6.6 kV/2.0 kA class superconducting fault current limiter used for power distribution substations, as the preliminary stage of development of current for trunk power systems. In order to reduce impedance under normal operating conditions and quickly switch to high impedance in a fault condition, the limiter consists of a pair of double-layer non-inductive superconducting windings connected in series. Each winding is wound with a 36-stranded AC superconducting wire having ultra-fine NbTi filaments in a high-resistivity matrix. The device successfully limited a 6.9 kA short-circuit current to 3.4 kA and transmitted continuous power at 2.0 kArms.

6.6 kV/1.5 kA-class superconducting fault current limiter development

The authors have developed and tested a 6.6-kV/1.5-kA-class fault current limiter wound with a 42-strand AC superconducting wire having ultrafine NbTi filaments in a high-resistivity matrix. In experiments, voltages up to 7.2 kV were applied to the limiter with phase angles of 0, 45, and 90 degrees . The limiter was able to limit the fault current to 1.8 kA from the 55-kA short-circuit current that would flow in a circuit without a limiter. >

Superconducting fault current limiter development

The authors have developed and tested a 400-V 100-A-class fault current limiter wound with AC superconducting wire with ultrafine NbTi filaments. The limiter consists of noninductively wound superconducting trigger coils and a superconducting limiting coil which acts as a reactor. Excessive fault currents initiate quenching in the trigger coils and these currents, which have flown in trigger coils in nonfault conditions, are commutated from the trigger coils to the limiting coil. In an experiment, a fault current level was successfully limited to 120 A with a limiter whose terminal voltage at the limiting condition was 420 V.