Type Superconducting Fault Current Limiter Research Articles

Design and experimental results of a 10 kV resistance-inductance type superconducting fault current limiter

Design and experimental results of a 10 kV resistance-inductance 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.

Analysis on Starting Current Limiting Characteristics of Induction Motor Using a Three-Phase Reactor Type Superconducting Fault Current Limiter

Analysis on Starting Current Limiting Characteristics of Induction Motor Using a Three-Phase Reactor Type Superconducting Fault Current Limiter

Enhancing low voltage ride-through capability of grid-connected photovoltaic plants using superconducting fault current limiters

Photovoltaic (PV) plants are playing an increasingly important role in the power system, and research focuses on their reliability and security have notably grown in recent years. To ensure the stable operation of PV plants, the low voltage ride-through (LVRT) strategy is attracting lots of academic and industrial interest. This is because the LVRT can prevent PV plants from being immediately disconnected during grid faults, which helps avoid slower recovery and extended power outages. Hence, this work proposes to enhance the LVRT capability of the PV plant using superconducting fault current limiters (SFCLs). Besides, the impacts of various types of SFCLs on the LVRT characteristics of the PV plant are thoroughly analyzed. Moreover, this work investigates the performance of various types of SFCLs in enhancing the LVRT capability of PV plants and achieving current-limiting effects, providing valuable insights for the design of SFCLs. A model of a real 35 kV grid-connected PV plant with SFCLs is built, and the theoretical analysis is validated. The results demonstrate the feasibility and superiority of using SFCL in enhancing the LVRT capability of PV plants, serving as a reference for the application of SFCLs in renewable energy stations.

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.

Current Limit Transfer and Recovery Characteristics of Resistive-Inductive Type Superconducting Fault Current Limiters

Current Limit Transfer and Recovery Characteristics of Resistive-Inductive Type Superconducting Fault Current Limiters

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.

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%.

Analysis on DC Fault Current Limiting Operation of Twice-Quench Trigger Type SFCL Using Transformer Considering Magnetizing Current and Current Limiting Reactor

As the penetration of distributed energy resources (DER) has increased, research on direct current (DC) power transmission and distribution has been actively performed. The DC system has the advantage of high-power transmission efficiency. However, it has a very large and rapid increase in fault current in the DC system directly after a fault occurs. As one of the countermeasures, studies on the application of the superconducting fault current limiter (SFCL) into the DC system have been conducted to protect major facilities from DC fault current, which is expected to alleviate the power burden on the DC circuit breaker through its quench operation. Among the studied DC SFCLs, the trigger-type DC SFCL using a transformer, which can achieve the peak DC fault current-limiting operation, has been suggested. However, the DC fault current-limiting operation, in the case of the DC SFCL with a current-limiting reactor (CLR), was analyzed to not be effectively executed in the steady state since the transient state directly follows the fault occurrence. In this paper, the DC fault current-limiting operation of a twice-quench trigger type SFCL using a transformer considering magnetizing current and its CLR was analyzed. Through DC fault current-limiting experiments according to the inductance of its current-limiting reactor (CLR), the effective current-limiting design of twice-quench trigger type SFCL using a transformer was described.

DC Fault Current Limiting Characteristics of Flux-Lock Type SFCL With Parallel Connection of Two Coils Using Twice Quench

In this paper, DC fault current limiting characteristics of DC flux-lock type superconducting fault current limiter (SFCL) with parallel connection between two coils were analyzed. DC flux-lock type SFCL with parallel connection between two coils was composed of two windings connected in parallel and two superconducting modules (SMs), which were connected in series with each secondary winding. DC flux-lock type SFCLs with a parallel connection between two coils and one SM with one secondary winding in series was thought to perform fault current limiting operation as in AC system. However, since the transient period after resistance generation in SM approaches into the constant value, unlike the AC system, there is a DC current limiting transient period. Therefore, the DC current limiting effect disappears in the DC system and the recovery characteristic after the fault is removed also disappears. To analyze the DC fault current limiting and recovery characteristics, a DC short-circuit test was per-formed, and the various behaviors of flux-lock type SFCLs in DC systems were investigated from the test results.

Pole-to-pole fault characteristics in VSC-HVDC transmission system with a resistance-inductance type superconducting fault current limiter

Pole-to-pole fault characteristics in VSC-HVDC transmission system with a resistance-inductance type superconducting fault current limiter

Quenched Flux-Coupling Superconducting Fault Current Limiter Scheme and Its Electromagnetic Design Method.

In order to solve the problem of excessive short-circuit current in the present power system, a fault current limiter has become a new type of power device with high demand and is one of the current research hotspots. The flux-coupling type superconducting fault current limiter (FC-SFCL) generates a current-limiting impedance through decoupling superconducting parallel inductance based on the circuit breakers' fractional interruption. The principle is simple, and the impedance is low during normal operation. It can directly use the existing circuit breaker to open a short circuit that is much higher than its own breaking capacity. Thus, it can be used for large-capacity fault current limiting and effective failure breaking. This paper focused on exploring and studying the implementation scheme of practical products of FC-SFCL. Considering that the quenched-type parallel inductance can limit the first peak value of the fault current, a quenched-type improvement scheme was proposed. Then, an electromagnetic design method based on the simplified calculation of the number of parallel tapes was proposed, which simplified the design process and reduced the design difficulty of the quenched FC-SFCL. Taking a 10 kV/500 A/5 kA quenched prototype as an example, its electromagnetic design was completed, and the performances of the non-quenched and quenched schemes were compared. The results showed that, compared to the non-quenched structure, the technical economics of the quenched one were more prominent, and it can be used preferentially for engineering prototypes. This study about the scheme of the quenched FC-SFCL and its electromagnetic design method is useful for promoting the implementation of the current limiter engineering prototype.

Design and Experimental Investigation of Three-Phase Inductive Type Superconducting Fault Current Limiter based on Current Injection Method

Design and Experimental Investigation of Three-Phase Inductive Type Superconducting Fault Current Limiter based on Current Injection Method

Utilizing Parallel Superconducting Element as a Novel Approach of Flux-Coupled Type SFCL to Limit DC Current in the System

To lessen the amount of energy lost during transmission, electricity is increasingly being sent using high-voltage lines. Transmission loss in a DC system is lower than in an AC system over long distances. The DC system can improve the efficiency of long-distance transmission by connecting power grids with different requirements. The DC method is becoming popular since it helps to keep the grid stable. Managing and blocking DC flow is crucial to system functionality. In this study, we explore the operation of a flux-coupled type superconducting fault current limiter (SFCL) in a DC system, where the two windings are connected in parallel to limit the fault current flow. A flux-coupled type SFCL is built by connecting two coils in parallel and a superconducting element (SE) in series with the secondary coil. The functions of an SFCL of the flux-coupled kind are equivalent in both direct and alternating current systems. Because of the opposing magnetic fluxes produced by the two coils, the voltage generated by the parallel connection of the coils is always zero. Inadequate SE leads to an increase in resistance, inhibiting the cancellation of opposing magnetic fluxes and hence a loss in power. Connecting the two coils in series allows voltage to be generated while the fault current is limited. To further validate the performance of SFCL with varying resistance and inductance, the system is additionally tested on the IEEE 39 bus system. The MATLAB/SIMULINK software suite is used to run the test system.

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.

Analysis on Three-Phase Ground Fault Current Limiting Operations of Three-Phase Transformer Type SFCL Using Two Superconducting Modules

Three-phase transformer type superconducting fault current limiter (SFCL) using two superconducting modules (SCMs) between secondary windings, which consisted of three-phase transformer windings wound on three legs of E-I iron core, one SCM with insulated connection with one secondary winding and another SCM with non-insulated connection between other two secondary windings, were suggested. For the suggested three-phase SFCL using two SCMs, its three-phase ground fault current limiting operations were analyzed through phasor diagram from electrical equivalent circuit. To verify three-phase ground fault current limiting operation of three-phase transformer type SFCL using two SCMs between secondary windings, three-phase ground faults were applied into three-phase power simulated system with the suggested SFCL. Through analysis on the test results, three-phase transformer type SFCL using two SCMs between secondary windings was confirmed to have effective three-phase ground fault current limiting operations through quenches of two SCMs.

A New Method to Enhance the Low Voltage Ride Through Capability of Doubly Fed Induction Generator Using Resistive Type Superconducting Fault Current Limiter

A New Method to Enhance the Low Voltage Ride Through Capability of Doubly Fed Induction Generator Using Resistive Type Superconducting Fault Current Limiter

Electromagnetic Design and Performance Analysis of a Hybrid-Type Superconducting Fault Current Limiter in Shipboard MVDC IPS

As medium voltage dc-based (MVDC) technology is widely considered in the shipboard power system (SPS), the short fault protection of shipboard IPS is urgent. Superconducting fault current limiter (SFCL) is an efficient way to solve the short fault problems in shipboard MVDC IPS. A hybrid type SFCL (H-SFCL) based on a non-quenching inductor and two resistors is electromagnetic designed in this study. The H-SFCL can limit short fault current with no quenching and little heating. In this study, the short fault mechanism and mathematical model of MVDC SPS bipolar short fault is analyzed. According to current limiting performance requirements in MVDC SPS, components parameters of H-SFCL are optimized matching. The scheme of annular structure inductors is proposed and electromagnetic design of a 10 kV/6 kA H-SFCL is completed based on a genetic algorithm. The ac loss and thermal stress of the designed magnet are evaluated. The simulation results show that the H-SFCL with optimized electromagnetic parameters meets the design requirements.

Current limiting characteristics of a resistance-inductance type superconducting fault current limiter

The superconducting fault current limiter (SFCL) can effectively and quickly limit the fault current, which is appropriate for the voltage source converter high voltage direct current (VSC-HVDC) transmission system to reduce the fault current. A new resistance-inductance type SFCL using the structure of the inductive superconducting coils is presented. The current limiting and inter-turn insulation characteristics of resistance-inductance type SFCL are studied. A simulation model is developed for the comparison of inductive and non-inductive type superconducting coils. The simulation results show that the inductive superconducting coils can significantly reduce the fault current rise rate by more than 42% over the non-inductive superconducting coils. The voltage distribution of the inter-turn channels is calculated by the presented method.Utilizing the voltage distribution, the electric field distribution can be obtained, which is important for the insulation design. Some inductive type pancake superconducting coils were fabricated, and the DC impulse current tests were carried out. The testing results and simulated results have a good agreement, which shows that the inductive type SFCL can effectively limit the fault current.