M. Majka

Bio: M. Majka is an academic researcher from University of Cambridge. The author has contributed to research in topics: Fault current limiter & Superconducting magnetic energy storage. The author has an hindex of 13, co-authored 25 publications receiving 361 citations.

Comparison of Inductive and Resistive SFCL

Abstract: This article presents a comparison of inductive and resistive superconducting fault current limiter built with the same length of high temperature superconducting (HTS) tape. The resistive limiter is constructed as a noninductive bifilar winding. The inductive coreless limiter consists of primary winding and secondary shorted winding. Both limiters are connected parallel to the additional Cu primary winding, which helps to reduce the power dissipated in the HTS windings during and after a fault. It also ensures that in cases of an HTS tape failure, the protected circuit will not be disrupted. The limiters are very fast and the first peak is almost equally limited by both types of limiters.

Design and Tests of Coreless Inductive Superconducting Fault Current Limiter

Abstract: In this work, we report on the design and tests results of a coreless inductive SFCL with a 600 A rated current for MV distribution system. The fault current limiter comprises of 4 identical units immersed in liquid nitrogen bath. Each unit consists of 3 windings. The primary and secondary windings made of 2G HTS tape SF12050 are magnetically coupled with the primary Cu winding. The high magnetic coupling between superconducting primary and secondary windings gives a low voltage drop on the limiter at nominal current. The presented solution reduces the size and the weight of the device. Tests performed at high power test facility prove the limiting capability of the coreless inductive SFCL.

Tests and Performance Analysis of Coreless Inductive HTS Fault Current Limiters

Abstract: Superconducting fault current limiters (SFCL) are designed to protect the electrical grid from faults that result from lightning strikes, downed power lines and other system interruptions. The rapid increase of impedance of the SFCL reduces the short current in the circuit. Several coreless constructions of inductive SFCLs have been tested. The space between the windings is the thick of the polyimide film kapton insulation to increase the coupling and reduces the leakage reactance. Both primary and secondary windings have been immersed in liquid nitrogen. The presented solutions reduce the size and the weight of the device. A few limiters based on HTS 1G and HTS 2G tapes has been described, tested and compared.

HTS Tapes Selection for Superconducting Current Limiters

Abstract: The superconducting fault current limiters (SFCLs) are highly effective solutions to reduce fault current in electric power system. The process of quenching may occur in all superconducting devices, but in fault current limiters this process must be fully controlled. Uncontrolled transition of the superconducting tape from the superconducting state to the resistive state may cause overheating and burning of the high temperature superconductor (HTS) tape and, consequently, lead to the destruction of the entire superconducting device. In this study, we described a simulation model to analyze the electrical and thermal behavior of the SFCL. By using this simulation model, we evaluated the transition of temperature of the REBCO coated conductor during the fault current limitation. We determined and described maximal parameters for the HTS tapes that can be applied to the superconductor without thermal degradation during fault.

Fault Current Limitation in Power Network by the Superconducting Transformers Made of 2G HTS

Abstract: The fault current limiting feature of the SC transformer with the HTS 2G windings provide protection and significantly reduce wear and tear for circuit breakers and other substation power equipment. A comparison of the short circuit currents of the 64 MVA transformer wound with copper and YBCO 2G HTS tapes is made in this paper. The results of the analysis show that the YBCO 2G tapes enable to built the superconducting transformer with the ability to limit the short-circuit currents. The superconducting windings require special considerations for the induced electromagnetic forces in order to limit them below the allowable tensile stresses. Strongly anisotropic Y-123 tape used in the winding of the transformer will be exposed to different orientations and amplitudes of the local magnetic field. If the transformer is going to act also as a fault current limiter, the uniformity of the transition of the transformer winding is crucial to avoid sectional responses of the transformer. Therefore it is essential to conduct systematic current-magnetic field measurements to define `constant current domain' for the conductor at a given operating temperature.

Case Studies In Superconducting Magnets Design And Operational Issues

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Fault Current Limiters in Power Systems: A Comprehensive Review

Abstract: Power systems are becoming more and more complex in nature due to the integration of several power electronic devices. Protection of such systems and augmentation of reliability as well as stability highly depend on limiting the fault currents. Several fault current limiters (FCLs) have been applied in power systems as they provide rapid and efficient fault current limitation. This paper presents a comprehensive literature review of the application of different types of FCLs in power systems. Applications of superconducting and non-superconducting FCLs are categorized as: (1) application in generation, transmission and distribution networks; (2) application in alternating current (AC)/direct current (DC) systems; (3) application in renewable energy resources integration; (4) application in distributed generation (DG); and (5) application for reliability, stability and fault ride through capability enhancement. Modeling, impact and control strategies of several FCLs in power systems are presented with practical implementation cases in different countries. Recommendations are provided to improve the performance of the FCLs in power systems with modification of its structures, optimal placement and proper control design. This review paper will be a good foundation for researchers working in power system stability issues and for industry to implement the ongoing research advancement in real systems.

Comparison of Inductive and Resistive SFCL to Robustness Improvement of a VSC-HVDC System With Wind Plants Against DC Fault

Abstract: For that wind plants are connected to an electric power grid through voltage source converter-based high-voltage direct-current (VSC-HVDC) transmission, the improvement of the VSC-HVDC system's robustness against a dc short-circuit fault is critical. This paper suggests the inductive and resistive superconducting fault current limiter (SFCL) to alleviate the fault current and enhance the system's transient behaviors. Each of the two SFCLs is installed in series with the dc transmission line, and once the fault is detected, the current-limiting inductance or resistance will be activated to affect the system characteristics. Herein, wind plants are based on doubly-fed induction generators, and related theoretical derivation and transient simulation analysis are done. From the results, both of the two SFCLs can limit the dc fault current, improve the dc-voltage sags and suppress the power fluctuations. By comparing the specific performance indexes including current-limiting ratio and restraining capability to voltage/power fluctuations, the resistive SFCL is more preferable than the inductive SFCL. At the end, the SFCL optimization technique considering current-limitation, voltage stability, and device cost are discussed, so as to further promote the SFCL's application in the VSC-HVDC system.

Application of a SFCL for Fault Ride-Through Capability Enhancement of DG in a Microgrid System and Relay Protection Coordination

Abstract: Concerning that a short-circuit fault happens inside a microgrid system, parts of distributed generation (DG) units may not meet the fault ride-through (FRT) requirements and will be enforced to disconnect. This paper suggests a modified flux-coupling-type superconducting fault current limiter (SFCL) to improve the DG's FRT capability, and investigates the relay protection coordination in the microgrid. The SFCL's structural principle is introduced, and according to the fault characteristic of the microgrid under its grid-connected and islanded statuses, the modified SFCL's application fields are conducted. Furthermore, the directional overcurrent protection and differential protection are proposed for the microgrid's two statuses, respectively. Based on the transient simulations in the MATLAB, the SFCL's positive effects on enhancing the DG's FRT capability can be confirmed, and also it will not affect the relay protection coordination. A comparison of the conventional distance relay protection and the proposed protection scheme is performed, and the latter has a better applicability than the former to match the SFCL. Finally, regarding the impacts of fault type and fault resistance on the FRT operation and the proposed protection, technical discussions are performed preliminarily, and the application value of the SFCL integrated with the proposed protection is clarified further.