Superconducting Fault Current Limiter Research Articles

High Voltage Calculations for a 380 kV Superconducting Fault Current Limiter

High Voltage Calculations for a 380 kV Superconducting Fault Current Limiter

Experiment Studies of a DC Inductive Superconducting Fault Current Limiter With Energy Dissipation Capability

Experiment Studies of a DC Inductive Superconducting Fault Current Limiter With Energy Dissipation Capability

Preliminary Design of DC Resistive Superconducting Fault Current Limiter for ASCEND

Preliminary Design of DC Resistive Superconducting Fault Current Limiter for ASCEND

Integration of Superconducting Fault Current Limiter and DC Circuit Breaker for Electric Aircraft DC Network

Integration of Superconducting Fault Current Limiter and DC Circuit Breaker for Electric Aircraft DC Network

Electrical Strength of Layered Insulation Systems in Liquid Nitrogen for Resistive Superconducting Fault Current Limiters

Electrical Strength of Layered Insulation Systems in Liquid Nitrogen for Resistive Superconducting Fault Current Limiters

Realistic Evaluation of Resistive Superconducting Fault Current Limiters in Distribution Networks

Realistic Evaluation of Resistive Superconducting Fault Current Limiters in Distribution Networks

Improving the recovery performance of superconducting fault current limiters using nitrogen/tetrafluoromethane mixed coolants

The superconducting fault current limiter (SFCL) improves the power grid safety by restricting the drastically increased current when the circuit fault occurs. However, the SFCL suffers from a long recovery time and can hardly recover to the superconducting state before the breaker attempts to reclose, which hinders its practical application. This paper presents the implementation of the rapid-recovery SFCL with efficient heat dissipation even if encountering a large fault current. This is enabled by thermal performance regulation of the working coolant through adding tetrafluoromethane (CF4) into the liquid nitrogen (LN2). The proposed mixed coolant features a high critical heat flux that suppresses the onset of film boiling. Controlled experiments were performed with the fabricated current-limiting coil immersed in the N2/CF4 mixed coolants containing 0, 20 and 40 mol% of CF4. Measured results regarding both quenching and recovery processes are reported, demonstrating an 85.4% reduction in recovery time for the 40 mol% composition compared to the conventionally used pure LN2. Analyses of the electrical parameters of the coil verify its effective quenching performance in the proposed immersion cooling system with an overall current limiting rate of over 55%. These findings lay a foundation for designing the rapid-recovery-type SFCL and facilitating its application in power systems.

Alternative analytical models for HTS tapes considering their AC hysteretic and resistive losses

This work proposes two alternative analytical models to evaluate the ac losses of high-temperature superconducting (HTS) tapes during their hysteretic and resistive modes. These models intend to extend the application range of state-of-the-art analytical models for current values higher than the critical one, i.e. for the resistive state, and to correctly predict the ac losses during the transition between the hysteretic and resistive modes. Two analytical models are proposed, one considering an extension of the Norris model for the HTS tape’s resistive mode and the other based on a sigmoid function to characterize the hysteretic losses and their smooth transition to the resistive mode. Analytical models capable of estimating ac losses of superconducting (SC) tapes are an important tool for the design of complex SC systems, such as SC fault current limiters, SC electrical machines and SC cables. The proposed models are validated experimentally, for a 1st generation BSCCO tape and a 2nd generation REBCO tape. Finite element simulation is also carried out to verify the accuracy of the proposed models. Results show that the proposed extended-Norris model presents some deviation at the transition between the hysteretic and resistive modes, while the sigmoid model presents very accurate results for the whole spectrum of applied current. Also, the parameters of the sigmoid models are independent of the tape geometry.

An asymmetric stabilizer layer structure of REBCO superconducting tapes for resistive superconducting fault current limiters

Used in resistive superconducting fault current limiters (R-SFCLs), REBCO tapes are required to have both large current limiting resistance and high over-current bearing capacity. The contradiction between high resistance and large over-current is the main difficulty in the design of REBCO-tape structure for R-SFCLs. In this paper, an asymmetric stabilizer layer structure of REBCO tapes has been proposed, fabricated and tested for R-SFCLs. Comparing to traditional tapes with a symmetric stabilizer structure, the REBCO tape with new structure showed a 59 % improvement in over-current bearing capacity: the peak current increased from 1020 A to 1620 A while keeping the same total resistance. Simulation calculation on the current distributions in every layer showed that the asymmetric structure is superior to the symmetric structure.

Conceptual design and simulation of a thermal matrix-type SFCL

Simultaneous quench is a prerequisite for achieving high-rated voltage and current in superconducting fault current limiters (SFCLs) based on superconducting thin films. In this article, we propose the T-MSFCLs, i.e. the matrix-type SFCLs (MSFCLs) with thermally-assisted simultaneous quenches, to mitigate hotspot and dielectric breakdown problems. We present the typology of the non-isolated and isolated T-MSFCLs and develop a computational model for evaluating their quench performances. The short-circuit simulation results demonstrates that the quench propagation between SFCL elements is easy to establish and is self-sustaining in the non-isolated and the isolated T-MSFCLs due to an electric-thermal coupling. The effects of Jc distribution and shunt layers on quench properties are studied. We find that T-MSFCLs always produce global quench despite having poor global uniformity ΔJc/Jc . The quench activation, quench development and the current-limiting properties of T-MSFCL are relevant to the parameters of shunt layers and the weakest SFCL element. The design parameters of the shunt layers are the main conditions for the maximum tolerance voltage and the maximum response rate of the T-MSFCL. By generalizing these findings, a method for capacity design of T-MSFCL is presented.

Mitigating commutation failures in HVDC systems with SFCL deployment

Commutation failures represent a prevalent issue encountered in line-commutated-converter high voltage direct current (LCC-HVDC) systems. As the widespread deployment of HVDC systems continues, the risk associated with commutation failures increases, posing a growing threat to power grids due to their potential to trigger severe consequences, including cascading failures and widespread blackouts. This research paper aims to address the significant issue of commutation failure within direct current (DC) systems through advocating for the use of resistive-type Superconducting Fault Current Limiters (R-SFCLs). To substantiate the efficacy of this proposed strategy, an array of simulations are executed using the PSCAD/EMTDC software. This comprehensive study investigates the performance characteristics of R-SFCLs configured with varying resistance values, scrutinizing their response under diverse fault resistance scenarios and distinct fault initiation times within the LCC-HVDC system. The outcomes of these simulations are that SFCLs confer significant advantages for mitigating commutation failures, surpassing traditional mitigation methods in terms of effectiveness. Consequently, SFCLs emerge as an optimal solution to prevent commutation failures in the HVDC systems.

Comparing Copper with Stainless Steel as a Stabilizer Layer in Resistive Superconducting Fault Current Limiters

Comparing Copper with Stainless Steel as a Stabilizer Layer in Resistive Superconducting Fault Current Limiters

Enhancing grid protection: The crucial role of resistive-type superconducting fault current limiters in transmission line current differential relays

Superconducting fault current limiters (SFCLs) offer an efficient means of limiting fault currents and supporting system reliability. However, they weaken the fault characteristics and reduce the sensitivity of traditional relay protection. The seamless integration of SFCLs with protective relays remains a complex and under-explored area, impeding their widespread industrial adoption. In parallel, current differential protective (CDP) relays are almost the primary protection for all high-voltage electrical equipment and are the cornerstone of global power system security. This paper fills a critical knowledge gap by researching the intricate interaction between resistive superconducting fault current limiters (R-SFCLs) and current differential protective relays. Our investigation commences with a comprehensive mathematical analysis, while researching the influence of R-SFCLs on CDP operation. Subsequently, we conduct a series of comparative experiments using the Matlab Simulink software platform. These tests evaluate the sensitivity, dependability, and security of CDPs in scenarios with and without R-SFCLs. The simulation results not only confirm the accuracy of our analytical framework but also shed light on the multifaceted relationship between R-SFCLs and CDPs. This research contributes to a deeper understanding of how R-SFCLs can be effectively integrated into power systems, offering a roadmap for enhancing grid protection.

Current-Limiting and Recovery Characteristics of Resistive-Type Superconducting Fault Current Limiters During Quench-Recovery-Requench Process

Current-Limiting and Recovery Characteristics of Resistive-Type Superconducting Fault Current Limiters During Quench-Recovery-Requench Process

Combining finite element and reinforcement learning methods to design superconducting coils of saturated iron-core superconducting fault current limiter in the DC power system.

A saturated iron-core type superconducting fault current limiter (SI-SFCL) can effectively restrict the magnitude of the fault current and alleviate the strain on circuit breakers in DC power systems. Design of a superconducting coil (SC), which is one of the key tasks in the SI-SFCL design, requires guaranteeing a sufficient magnetic field, ensuring optimization of the shape and size, minimizing the wire cost, and satisfying the safety and stability of operation. Generally, finite element method (FEM) is used to calculate and evaluate the operating characteristics of SCs, from which it is possible to determine their optimal design parameters. When the coil is complex and large, the simulation time may range from hours to days, and if input parameters change even slightly, the simulations have to be redone from scratch. Recent advances in deep learning represent the ability to be effective for modeling and optimizing complex problems from training data or in real-time. In this paper, we presented a combination of the FEM simulation and deep Q-network (DQN) algorithm to optimize the SC design of a lab-scale SI-SFCL for a DC power system. The detailed design process and options for the SC of SI-SFCL were proposed. In order to analyze the characteristics related to the electromagnetic properties and operational features of the SC, a 3D FEM model was developed. Then, a DQN model was constructed and integrated with the FEM simulation for training and optimizing the design parameters of the SC in real-time. The obtained results of this study have the potential to effectively optimize the design parameters of large-scale SI-SFCL development for high-voltage DC power systems.

Fault current limiter based on high temperature superconductors

High Temperature Superconductors (HTS) made the Superconducting Fault Current Limiter (SFCL) a reality in power electric grids. Resistive SFCL, which is the subject of this article, is based on a unique property of superconductors to quench from a non-dissipative to a high dissipative state above a given current. SFCL is an attractive response to the poorly solved problem of fault currents in power electric grids and makes it possible to enhance the security and quality of electricity, something that matters more than ever. Liquid nitrogen cryogenics – which is possible thanks to HTS- makes the cryogenics user friendly. In-field SFCL operations confirm this. Second generation (2 G) HTS materials or Coated Conductors suit well to SFCL. Due to its high interest, SFCL has been the subject of a great deal of research and development. In terms of Technology Readiness Level (TRL) it reaches 8 with several in grid test experiences.Here a short history of SFCL is presented with a highlight about Curl 10, Ampacity and SuperOx devices. The two major locations in the grid are reported: grid coupling and feeder protection. The quench phenomena is described in a bit more detail before the basic design (length and cross section) is presented. The design is primarily thermal, considering two extreme operations: fault with very high prospective current (clear short-circuit) and fault with prospective current close to the minimum runaway current along the length. This operation is called the hot spot one. It is due to the intrinsic variation of the critical current along the length and to the low Normal Zone Propagation Velocity (NZPV). The cost of the superconducting conductor is given, showing no bottleneck for an economic development. All the more it is still possible to lower the cost with some developments. This article ends with two real advances presently underway: Current Flow Diverter (CFD) and Sapphire substrate superconducting 2 G tape. CFD aims to increase the NZPV, to still further secure the operation and to reduce the conductor cross section. The use of sapphire substrates allows to reduce significantly the length of the design.

The optimal allocation of H-SFCL in MVDC SPS

Medium voltage direct current shipboard power system (MVDC SPS) is the development trend of navy in the future. At present, one of the bottlenecks restricting the development of MVDC SPS is that the short fault. There is a lack of effective means to limit short fault current to protect MVDC SPS. This paper presents a method of applying a hybrid type superconducting fault current limiter (H-SFCL) to MVDC SPS protection. The architecture and system modeling of MVDC SPS are introduced, and the mechanism of bipolar DC short fault is analyzed. The topology and working principle of H-SFCL are introduced. The small-scale prototype experiment is done, the current limiting effect of H-SFCL is compared with resistive type superconducting fault current limiter (R-SFCL) and flux-coupling type superconducting fault current limiter (FC-SFCL) in the prototype test, so as to verify the superiority of H-SFCL. A dual objective hierarchical optimization configuration method is proposed, and the number and position of H-SFCLs are verified on a four-terminal system, as well as multi-objective optimization for H-SFCLs. A fault isolation and H-SFCL optimal allocation evaluation model is proposed; An improved method suitable for fault isolation and multi-objective optimal allocation of H-SFCLs is proposed to address the issue of breaking timing between internal switches in H-SFCLs and external circuit breakers in the optimization process. The research results indicate that the proposed optimal allocation method can optimize the inductance, resistance, and switch breaking time inside the current limiter, and can match the timing with the external circuit breaker; The proposed multi-objective optimization configuration method has a maximum effective individual ratio of 88% in the first 20 generations of improvement, and the improved iteration speed has significantly increased. In the 5th generation, the effective individual ratio can reach 100%.

Impact of Saturated Iron Core Superconducting Fault Current Limiters on Traveling-Wave-Based Protection

Impact of Saturated Iron Core Superconducting Fault Current Limiters on Traveling-Wave-Based Protection

Low voltage protection method of DFIG based on rotor-side double current limiting circuit

A doubly fed induction generator (DFIG) configured for crowbar protection faces the following problems during low voltage ride through (LVRT): delayed input of crowbar protection and the difficulty in coordinating current limiting targets and DC voltage overrun with constant resistance rectification. A low voltage protection method of a DFIG based on a rotor-side double current limiting circuit is proposed. The rotor current characteristics during a fault are analyzed from a time domain perspective and used as a basis for resistance setting. The transient response characteristics of a resistive superconducting fault current limiter (RSFCL) are used for fast initial suppression of rotor currents. The adaptive crowbar resistance adjustment method is used to realize the coordinated consideration of current limiting and DC voltage non-overrun. The simulation results show that the proposed protection method effectively shortens the actual input time of the current limiting circuit and has good suppression ability for the rotor current at the early stage of fault. The adaptive and flexible resistance setting of the controllable crowbar circuit ensures that the DC voltage does not exceed the limit during the fault current limiting period, which helps improve the LVRT capability of doubly fed wind turbines.

Effect of Shunt Resistor Value on the Performance of Resistive Superconducting Fault Current Limiters

Effect of Shunt Resistor Value on the Performance of Resistive Superconducting Fault Current Limiters