Resistive Type Superconducting Fault Current Limiter Research Articles

Electromagnetic Thermal Analysis on Variable Resistive-Type Superconducting Fault Current Limiter

Electromagnetic Thermal Analysis on Variable Resistive-Type Superconducting Fault Current Limiter

Comparative study on the impact of different E-J relations on the performance of resistive superconducting fault current limiters under high and low impedance faults in cryo-electric aircraft

To achieve the goal of zero emission in aviation, it is critical to advance electric aircraft technologies, especially in short to medium range flights. Superconducting fault current limiters (SFCLs) have shown promising potential in electric aircraft system as a protection solution to limit the peak of fault current. Many research works focused on the SFCL performance under low impedance faults, where the fault current is much higher than the nominal current and the SFCL will transit to normal (metal) state quickly. However, there are limited reports on investigating the SFCL reacting to high impedance faults for electric aircraft system, where the SFCL does not abruptly transit to normal state. In this paper, we built an electric-thermal coupled model in MATLAB which simulates the behaviour of a resistive type SFCL both under low and high impedance faults. We investigated three mathematical relations of local electric field E and local current density J representing the transition from superconducting state to normal state, both under high and low impedance fault. The three mathematical relations are classic E-J power-law, modified E-J power-law and two- stage E-J power law. The electric-thermal model of the SFCL incorporating all these three types of mathematical relations, respectively, have been used to calculate the SFCL responses under high and low impedance faults, and compared with each other, as well as testing results. The limited fault current, voltage drop, resistance and temperature variations in the SFCL are observed and analysed. The results have shown that the proposed SFCL model is able to accurately characterise a resistive type SFCL under both high impedance and low impedance fault.

A novel controllable capacitor commutation based superconducting hybrid direct current breaker

Featuring low power loss and high reliability, voltage source converter medium voltage direct current (VSC-MVDC) systems have been widely employed for grid-tied renewable energy applications. To maintain high operational safety, circuit breakers are needed to isolate faulted powerlines by comprehensively considering response speed and installation cost. Research efforts have been put to realizing DC fault isolation by coordinating resistive type superconducting fault current limiter (R-SFCL) and integrated-gate-commutated-thyristor (IGCT) based hybrid DC circuit breaker. In this paper, a controllable current commutation based superconducting DC circuit breaker (CCCB-SDCCB) is proposed. By integrating R-SFCL with IGCT based hybrid DC circuit breakers, the current interrupting capacity can be greatly enlarged with the advantage of low cost and fast speed, and hence the overall cost for suppress large fault currents can be greatly reduced for MVDC systems. In addition, a new current injection circuit branch using H-bridge structure is designed to recycle the residual capacitor voltage from the previous fault stage to trigger the IGCTs without the capacitor pre-charging process. Simulation results show that the fault current can be successfully suppressed from 24.2 to 2.1 kA and fully interrupted within 4.11 ms by the proposed CCCB-SDCCB.

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.

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

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%.

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

Resistive-type superconducting fault current limiters (r-SFCLs) have generated great interest for research and technical applications. This is attributed to their superior features, which include self-action, fast response, and simple operation. In low line impedance systems, r-SFCLs are seen as a viable protective mechanism for limiting high-magnitude fault currents. However, overcurrent caused by faults results in an increased temperature of the r-SFCL, possibly damaging the coils. Thus, the r-SFCL must be appropriately engineered to protect it while still allowing for effective fault current limitation. To achieve this goal, an appropriately sized shunt resistor must be used. Adding a shunt resistor benefits the r-SFCL in several ways, from lowering its maximum temperature to speeding up its recovery. Additionally, the shunt resistor protects the r-SFCL from excessive surges in temperature by giving the current an alternative path to flow down, thus saving it from further damage. A multilayer thermoelectric model was developed to examine the thermoelectrical behavior of the r-SFCL coil throughout a fault occurrence and the subsequent recovery period using three shunt resistors ranging from 4 to 16 Ω. MATLAB®/Simulink was used as the simulation platform in this study. The dependence of the current limitation capability and the voltage profile on the shunt resistor value was studied compared to the basic case without an r-SFCL. Increasing the shunt resistor value led to an enhanced ability to limit fault currents, although at the cost of higher temperatures and a longer recovery time. This study also presents guidance for optimizing the design parameters of r-SFCLs.

Current limiting and recovery characteristics of an AC fast recovery superconducting fault current-limiting breaker

With the continuous development of the power grid, the high short-circuit fault current threatens the reliability of the power system. When the short-circuit current is greater than the interrupting capacity of the circuit breaker, the fault current will not be interrupted. Resistive-type superconducting fault current limiter (R-SFCL) has little loss in normal conditions. When a short-circuit fault occurs, R-SFCL can respond within a few milliseconds and limit the fault current. But the recovery time of R-SFCL is too long to satisfy the reclosing demand in the power grid. In this paper, an AC fast recovery superconducting fault current-limiting breaker (FR-SFCB) is proposed. With the operation of a fast switch connected with the superconducting coil, one of the parallel superconducting branches is disconnected, which could provide higher current limiting resistance and decrease the fault current need to be interrupted in fault conditions. Because of the shorter current flowing time, the heat generation and temperature of the advanced disconnected branch are less which can reduce the recovery time significantly. An experimental model is established based on thyristors and superconducting tapes. The effects of prospective current (I p) and the types of superconducting tapes on the current limiting resistance and recovery time of FR-SFCB are investigated. Experimental results show that with the disconnection of the flowing branch, the current limiting resistance of the proposed FR-SFCB increases to more than 3 times of the normal R-SFCL. At the same time, when the FR-SFCB resistance after current limiting is lower than the room temperature resistance, the recovery time of the flowing branch decreases by at least 50%. With access to fast switches, the proposed FR-SFCB can suppress the short-circuit fault current effectively and improve the stability of the power system.

Optimal placement of resistive superconducting fault current limiter by considering short‐circuit current and transient stability of power system

AbstractHigh level of fault currents has become one of the most challenging issues, along with increased electrical energy consumption and power grid expansion. However, some of the previous work was limited to installing limiters on designs and installing them on small plans. Here, the optimal placement of a resistive‐type superconducting fault current limiter (RSFCL) to achieve good power system transient stability is proposed. The proposed method has several advantages. First, procedure fault analysis is applied to consider the magnitude of the short‐circuit currents and the line located close to the generator for the placement of the device. Compared with other methods, it can directly find the exact line to be installed RSFCL. Second, the stability assessment is validated using the time domain simulation by installing limiters with varying capacities in any location. Third, parameters were analysed to evaluate the proposed method's effectiveness, including angular speed, rotor angular velocity, and generator rotor angle in a multi‐machine system. The result reveals that the placement of the limiter on the line with the most significant short‐circuits value on the line closest to the generator increases the power system stability more than the placement in other locations.

Mechanism of Recovery Performance Improvement With Porous-Stabilized REBCO Tape for Resistive-Type Superconducting Fault Current Limiters

Resistive-type superconducting fault current limiters (R-SFCLs) utilizing rare-earth barium copper oxide (REBCO) tapes have been developed to limit fault currents. To balance recovery and current-limiting performances, a porous-stabilized REBCO tape was proposed. The experimental results showed that using a porous stabilizer with the REBCO tape and insulating epoxy reduced recovery time to 25%. However, the underlying mechanisms of this improvement in recovery performance are not yet clear. The aim of the present study is to understand these mechanisms. To do so, a vapor-film-collapse model was proposed to clarify the impact of the insulating epoxy on vapor film collapse. This model suggests that when liquid nitrogen (LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) comes into contact with the insulating epoxy, it causes a rapid decrease in the temperature of the insulating epoxy surface, leading to the collapse of the vapor film. Additionally, a liquid-retention model was proposed to investigate the effect of the porous stabilizer. This model indicates that if the porous stabilizer can retain LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , the equivalent heat flux observed in experiments can be achieved through evaporation of the retained LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> .

Simulation study of integrated‐gate‐commutated‐thyristor based superconducting hybrid direct current circuit breaker

AbstractWith the development of a distributed generation, direct current (DC) load and energy‐storage equipment, voltage‐source‐converter‐based medium‐voltage DC systems (VSC‐MVDC) have attracted more attention due to its low power consumption, high reliability, independent power control and so on. However, VSC‐MVDC has the problem of DC fault isolation, which requires the fast‐acting DC circuit‐breakers to isolate faulty lines and ensure low cost. This problem can be solved by coordinating resistive type superconducting‐fault‐current‐limiter (R‐SFCL) and integrated‐gate‐commutated‐thyristor (IGCT) based hybrid circuit breaker. Based on this, IGCT based superconducting DC circuit breaker (SDCCB) is proposed and analysed. Combining R‐SFCL with IGCT could realise large current limiting and interruption and ensure low cost. In addition, the IGCT based hybrid DC circuit breaker (IGCT‐HDCCB) is compared with the traditional insulated gate bipolar transistor (IGBT) based hybrid DC circuit breaker (IGBT‐HDCCB) to evaluate which circuit breaker is more suitable for VSC‐MVDC. The results show that, coordination based on R‐SFCL and SDCCB, the fault current is successfully limited from 17.6 to 2.1 kA, and then interrupted within 3.8 ms. In addition, IGCT‐HDCCB overcomes the disadvantage that IGCT has less interrupting capacity than IGBT, retains the advantage of low cost of IGCT and is more suitable for MVDC system.

A PSO-Based Approach for Optimal Allocation and Sizing of Resistive-Type SFCLs to Enhance the Transient Stability of Power Systems

Transient stability improvement of power systems in the event of short-circuit faults has always been an important issue in power systems analysis and studies. Resistive-type superconducting fault current limiters (RSFCL), owing to their capability in restricting fault currents, have been often taken into account as an efficient method to improve the transient stability of a power system. Regarding technical constraints as well as economic concerns, optimal allocation and sizing of RSFCLs in a power system play a crucial role in their efficient utilization. This paper aims to continue the authors’ previous work and enhance the transient stability of power systems by proposing an optimization approach for optimal sizing and the allocation of various candidate numbers of RSFCLs, as the most employed type of SFCL and the most efficient one in transient stability improvement. To solve the optimization problem, a PSO-based algorithm is solved in MATLAB through an objective function and related constraints. The efficacy of the proposed algorithm is evaluated by numerical studies on the IEEE 39-Bus New England system in various scenarios through the assessment of critical fault clearing time (CCT) as well as the generators rotor angle deviations as two crucial criteria for the transient stability of power systems. Simulating the optimization results in DIgSILENT Power Factory indicates an evident enhancement of the power system transient stability via employing optimized RSFCLs resulted from the proposed optimization algorithm. Moreover, the level of transient stability enhancement highly depends on the number of optimized RSFCLs employed in the power system. The results of this paper present a helpful guideline for power system planners to select an appropriate stability scheme based on RSFCLs besides other related technical and economic issues.

Visualization experiment on cryogenic boiling heat transfer and recovery characteristics in the first and second quench of RSFCLs

The resistive type superconducting fault current limiter (RSFCL) based on YBCO superconducting tape has great potential to protect the large high-voltage power grid. The rapid recovery of the YBCO superconducting tape after the 1st quench not only affects the reclosing time but also the 2nd quench response. Besides, the retention of bubbles generated from the liquid nitrogen (LN2) boiling during the 1st quench may also worsen the heat transfer and the recovery process of the 2nd quench, which is seldom revealed at present. In this work, the effects of the different initial states, i.e., the recovery stages after the 1st quench, on the 2nd quench of YBCO tapes in LN2 bath are studied. A visualization experimental setup is used to study the 1st and 2nd quench performance from the perspective of LN2 boiling bubble dynamics. Two characteristic parameters, in terms of the peak temperature Tpeak and the recovery time extension ratio ε, are adopted to describe the deterioration of quench and recovery performance. The experimental results show that the shorter the time interval between the two quenches, the greater the recovery time extension ratio ε, and the higher 2nd peak temperature Tpeak,2. Furthermore, the visualization results show that the film and the remaining bubbles after the previous quench are the main factor affecting the next quench and recovery. The maximum difference of the peak temperature between these two quenches can be as high as 46.4 K, and the extension ratio could reach 2.06. Even when the tape has recovered to about 77.3 K at the beginning of the 2nd impulse, Tpeak,2 still reaches 155.8 K due to the presence of remaining bubbles, which is 5.2 K higher than that of the 1st quench. The greatly prolonged recovery time and the sharp increase in peak temperature will further increase the risk of YBCO tape burnout. Therefore, this research can provide a more comprehensive and reliable reference for the RSFCL system to safely response repetitive current impulses.

Development of cryogenic insulation supporter module for a 220 kV 2G-tape-based resistive fault current limiter

Resistive type superconducting fault current limiter (R-SFCL) is one of the most promising candidates to suppress fault currents in power grids. However, the violently boiled cryogen liquids, commonly liquid nitrogen, occurred due to fault currents, poses a crucial cryogenic insulation challenge for R-SFCL. Here we report the design and development of a Cryogenic Insulation Supporter Module (CISM) for a 220 kV R-SFCL. First, we present the design and test of the prototype Cryogenic Insulations Supporter (CIS). The developed CIS passed the high voltage tests under operating conditions. Following on this, we then present the design of CISM, which consists of 14 CISs, with the length and outer diameter of 12 m and 2.5 m, respectively.

Resistive SFCL Integrated Ultrafast DC Hybrid Circuit Breaker for Subsea HVDC Transmission Systems

High voltage direct current (HVdc) power transmission systems do not encounter any natural zero crossing unlike the ac systems, and hence, the dc circuit breakers employed should be fast-acting and reliable to ensure safe operation. Circuit breakers (CBs) that have fast response time with lower energy loss dissipation are required for subsea HVdc transmission systems. This article investigates the performance of various CB topologies, including ultrafast coupled inductor hybrid CB (CIHCB) topology without and with the integration of resistive-type superconducting fault current limiter (R-SFCL) for a 100-kV, 100-MW HVdc transmission systems. It is found that the addition of R-SFCL with 1.7-ms response time decreases the peak current through the breaker and, hence, the power dissipated in the CB during short-circuit fault conditions. Thus, the rating of CB can be significantly decreased with the proposed topology. Furthermore, a comparison of power loss in CIHCB with the existing topologies, such as mechanical CB, resonant CB, and HVdc-hybrid CB, are also presented in this article.

A Fault Detection Scheme in MTDC Systems Using a Superconducting Fault Current Limiter

This article proposes a fault detection scheme for modular multilevel converter-based multiterminal dc (MMC-MTdc) girds based upon a resistive-type superconducting fault current limiter (RSFCL). By analyzing the characteristics of the currents through the faulted and healthy lines in an MMC-MTdc system, the theoretical foundations of the scheme are established. This yields a fault detection scheme with fault identification, fault pole discrimination, and high-resistance tolerance abilities. Extensive simulations confirm that the proposed detection scheme can identify the metallic short circuit fault within 1 ms, with the ability to promptly detect faults with high resistance in less than 3 ms taking the communication delay into consideration. This method does not cause any mal-operation of dc circuit breakers as a result of faults on adjacent lines and power order changes. The proposed scheme has immunity to noise and provides full-length protection of the protected transmission line. Simulation results show significant suppression of both the amplitude and the rate-of-rise of the fault current during the fault detection process, which enhance the reliability and stability of the protected grid.

DC Breakdown Characteristics of Needle–Needle–Plane Electrodes With Insulation Barrier and Thermal-Induced Bubbles in Liquid Nitrogen

Insulation barriers are an effective way to improve the insulation strength of the resistive-type superconducting fault current limiters (R-SFCLs). The objective of this article is to obtain the dc discharge characteristics of composite insulation systems including two liquid nitrogen (LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) gaps in series, but separated by a solid insulation barrier mixed with vapor bubbles. The needle–needle–plane stainless steel electrodes with the insulation barrier and bubbles generation systems are used to simulate the electric strength under quenching conditions of the R-SFCLs. The results show that the composite systems’ breakdown characteristic switched from insulation barrier breakdown to surface flashover with the insulation barrier approaches the needle electrodes side. The breakdown voltage of the composite systems decreased due to the thermal induced bubbles. The presence of the bubbles increases the probability of the surface flashover of the insulation barrier. The results have guiding significance for the design of the high-voltage R-SFCLs.

Modelling of Resistive Type Superconducting Fault Current Limiter for HVDC Grids

The protection of high voltage direct current (HVDC) grids is a challenge considering that the protection system must detect, locate, and interrupt large fault currents in a few milliseconds. Resistive type superconducting fault current limiters (R-SFCL) can help solve that difficult task, reducing the extremely demanding ratings of HVDC circuit breakers. This paper presents different approaches to model R-SFCLs in order to analyze their suitability for assessing the performance of HVDC grid protection, including the step model, the exponential model, the RQ model, and the magneto-thermal model. In the first instance, the R-SFCL models are evaluated in a test grid to analyze their parameterisation and select the most adequate model for the study of HVDC grids. The RQ model is finally chosen for its simplicity but closer behavior to the magneto thermal model in terms of fault resistance dependency and resistance evolution curve. Then, the performance of an RQ type R-SFCL model in conjunction with a mechanical circuit breaker is evaluated in a multiterminal HVDC grid with different fault cases. This way, fault currents are greatly decreased as well as circuit breaker requirements. Hence, the R-SFCL under study enables a reliable protection of the HVDC grid.

Impact of Current Transfer to Porous Stabilizer on Recovery Performance of Resistive-Type Superconducting Fault Current Limiters Using REBCO Tapes

Porous-stabilized rare-earth barium copper oxide (REBCO) tape is an effective structure to solve a trade-off between the current-limiting and recovery performances of the resistive-type superconducting fault current limiters (RSFCLs). In the present study, a current-transfer-type porous-stabilized REBCO tape was proposed to suppress hot spots on the tape, which caused a recovery delay. In this type of REBCO tape, two porous stabilizers with different roles are utilized. The boiling heat transfer performance is improved with one of the porous stabilizers fixed with insulating epoxy on the tape while the current is transferred to the other porous stabilizer to decrease the Joule heating in the hot spot. To design the structure of the current-transfer-type porous-stabilized REBCO tape, the heat transfer performance with a porous medium and insulating epoxy was evaluated. The results indicated that there were suitable specifications for the porous medium and insulating epoxy for high heat transfer performance. The recovery performance of the current-transfer-type porous-stabilized REBCO tape was evaluated with the prototype using the selected porous stabilizer and insulating epoxy. The experimental results showed that the tolerable Joule heating was dramatically improved via current transfer to the porous stabilizer owing to the suppression of the temperature rise of the hot spot. The recovery time was shortened to 0.8 s. The present study showed one way to suppress the hot spots with a simple structure while maintaining the high electrical resistance of the REBCO tape.