A new directional relaying approach for transmission lines considering hybrid superconducting fault current limiters

An Optimization Approach for Fault Current Limiter Installation Considering Distributed Generation Impact and Circuit Breaker Constraints

Hybrid HVDC circuit breakers (H-DCCB) are an ideal choice for fault current interruption in voltage source converter (VSC) based multi-terminal HVDC (MT-HVDC) grids. However, in case of a DC side short circuit fault in VSC based MT-HVDC girds, the fault current escalates rapidly. This imposes significant electrical and thermal stresses on H-DCCB components, leading to decrease in its operational life span and even component damage. To address this challenge, this paper proposes the integration of a novel thyristor responsive adaptive fault current limiter (TRA-FCL) topology designed specifically to mitigate these stresses. The proposed TRA-FCL, comprising resistive, capacitive, and thyristor-based components, operates by inserting fault current limiting resistors during fault conditions. This action effectively reduces the fault current magnitude, thereby reducing the electrical and thermal burden on the H-DCCB and enhancing the overall reliability of the MT-HVDC grid. Simulation results, obtained using PSCAD/EMTDC software, confirm that the TRA-FCL can prevent VSC blocking, ensuring continuous grid operation and reducing the operational stress on H-DCCB.

This work presents the performance and efficiency analysis of solid-state power electronic devices in two complementary applications: fault current limiting and renewable energy integration. A solid-state Fault Current Limiting and Interrupting Device (FCLID) based on a Switched Capacitor (SC) circuit is evaluated for its ability to perform power factor correction and voltage regulation during normal grid operation. Particular focus is given to switching losses in semiconductors, analysed using the PSIM Thermal Module. The 90° phase shift observed between current and voltage in SC circuits is contrasted with in-phase behaviour in DC-DC converters. IGBT losses are calculated and shown to closely align with simulation and literature-based estimates. The second part of the study investigates a grid-connected photovoltaic (PV) system with power smoothing capability, designed to mitigate output fluctuations due to environmental variability. A bidirectional DC-DC converter and a partially controlled lithium-ion battery are used to reduce voltage flicker and improve grid stability. PSIM simulations incorporate MPPT control, inverter modelling, and real-world component characteristics. Losses are primarily concentrated in switching transistors, diodes, and inductors. Across both systems, efficiency is critically evaluated as a primary determinant of performance and economic viability. The simulated and analytical loss results show agreement within 1%, thereby validating the modelling approach. The findings indicate that lower switching frequencies consistently yield overall system efficiencies above 96%, irrespective of whether MOSFETs or IGBTs are employed. However, the study also reveals that reverse recovery losses become negligible compared to conduction losses only at low switching frequencies (<10 kHz) and low current slew rates (di/dt < 100 A/µs). Finally, the analysis demonstrates that practical implementation factors can increase total power losses by up to 21%.

A novel flexible fault current limiter for DC distribution applications

Electric distribution networks are witnessing rapid growth in distributed generation units (DGs), with renewables forming the majority of new connections. To raise the maximum DG hosting capacity, operators increasingly consider transitioning from strictly radial feeders to selectively meshed arrangements, allowing improved sharing and balancing of power flows across circuits. When we mesh the network, prospective short-circuit currents rise. That makes protection coordination harder and pushes us to specify higher-rated transformers and primary gear. Superconducting fault current limiters (SCFCLs) present a compelling pathway to mitigate these elevated fault duties without compromising normal operation. This study examines a strategy that retrofits existing distribution topologies with meshed (looped) operation supported by SCFCLs to enable higher DG penetration. The operating concept leverages SCFCLs to permit rapid reconfiguration from meshed to radial topology when a fault occurs, thereby constraining fault current magnitudes. Because radial operation in the faulted state matches current practice, the approach preserves existing protection schemes and avoids changes to equipment ratings or layouts. In normal service, the network runs meshed to improve power-flow management; under faults, it reverts to radial behavior to contain short-circuit levels. This article tests that premise by evaluating whether SCFCL-assisted meshing (superconducting fault current limiter) can increase DG hosting capacity while remaining compatible with existing protection philosophies and equipment—minimizing or eliminating redesigns and upgrades.

In order to break the bottleneck in the teaching and research of superconducting current limiting technology, this paper proposed an integrated platform based on a resistive-type superconducting current limiter (RSFCL). Through a user-programmable software interface, the dynamic working process of the RSFCL was simulated and analyzed, along with the self-triggered quench characteristics, internal current distribution, and instantaneous temperature evolution process under different fault conditions. This platform employed a superconductor–circuit–temperature coupling model to simulate the current limiting characteristics of the RSFCL under various AC/DC and transient conditions. This effectively helps the users understand the electrothermal coupling mechanisms of the RSFCL but also provides the researchers with an efficient simulation tool to analyze superconducting properties, optimize fault current limiter topologies, and validate system-level fault protection strategies. The platform’s simulation results align well with theoretical analyses, offering a reliable auxiliary tool for teaching and research in superconducting power technology.

In this paper, superconducting fault current limiter (SFCL) operation in the presence of a long-duration fault is presented. The SFCL device utilizes second-generation high-temperature superconducting (2G HTS) tapes, which exhibit zero resistance under normal operating conditions. When the current exceeds the critical threshold specific to the superconducting tape, then it undergoes a transition to a resistive state—a phenomenon known as quenching. As a consequence, this leads to introducing impedance into the circuit, effectively limiting the magnitude of the fault current. Additionally, this transition dissipates electrical energy as heat within the material. The generated energy corresponds to the product of the voltage drop across the quenched region and the current flowing through it during the fault duration. In specific configurations of the power system, it is expected that the SFCL should limit the fault current for an extended period of time. In such a situation, a certain amount of energy will be generated, and it must be verified that the tape loses its properties or parameters (e.g., lowering the critical current value) or is destroyed. Therefore, experimental tests of the tapes were conducted for various short-circuit current, voltage drop, and short-circuit duration values to assess the effect of the amount of generated energy on the 2G HTS tape. Additionally, recommendations are presented on how to protect the SFCL during long-lasting short circuits.

Enhancing the performance of active mechanical circuit breakers in HVDC systems using a superconducting fault current limiter

Recovery characteristic of Superconducting Fault Current Limiters (SFCLs) is a critical factor during their design process. After a low impedance fault, SFCL cannot return to the superconducting state abruptly, due to the large heat generation during fault and the resultant high temperature above critical temperature Tc. Fast recovery of SFCL will ensure fast reclosing and continuation of power supply in the power distribution network of an e-aircraft. In this work, a skeleton-based design of helical bifilar SFCL was proposed to achieve fast-recovery. The new structure ensures a larger cooling surface area between the high temperature superconducting (HTS) tape and the coolant, thus enhancing recovery performance and reducing the recovery time of the SFCL. Multiple fault current limitation characterization profiles including limited current, voltage drop across the SFCL, resistance and temperature of the SFCL were analysed and compared with that of the classic helical bifilar SFCL. Studies were conducted on different initial operating temperatures, different HTS tape length usages, and different reclosing time ranges. The results show that the recovery time has been shortened from 2.2 to 0.49 seconds by the proposed new SFCL, as compared to the classic helical bifilar SFCL. This skeleton-based fast-recovery SFCL provides new ideas for fault management in future cryo-electric aircraft.

The LCC type DC grids forming method and fault ride-through strategy based on fault current limiters

Transient Stability Enhancement Control for VSG Considering Fault Current Limitation and Reactive Power Support Constraints

A coordinated control strategy with solid state fault current limiter and supercapacitor energy storage system for enhancing LVRT capability of DFIG-based wind energy conversion system

Impact of Saturated Iron-Core Superconducting Fault Current Limiters on Traveling Wave Based Fault Location in DC Transmission Lines

Effectiveness and Robustness Design of 500 kV HVDC Presaturated Iron-Core Fault Current Limiters

Multi-Physics Characteristic Simulations of a Current-Limiting CORC Conductor for a 35 kV/1.5 kA Superconducting Fault Current Limiter (SFCL)

Superconducting fault current limiters (SFCL) are protective devices that limit the current in power lines when it suddenly increases above a certain safe level as a consequence of a fault. This element is connected in series with the line and has a null impedance when the line current is below the safe value (limit current) but significative increase the impedance when the line current tries to surpass this value. The variance of impedance is only due to the internal state of superconductors, without the participation of any mechanical element. Obviously, there are not any similar elements manufactured with conventional technology. There are two basic types of SFCL: those that present a resistive impedance (R-SFCL) after transition, and those which present an inductive impedance (I-SFCL). The authors are working on an SFCL concept that includes both mechanisms operating interactively. In this work, the combined transition mechanism is explained, the prototype under study is presented, and some theoretical and experimental results are shown

Enhancing Performance of Doubly Fed Induction Generator (DFIG) Wind Turbines by Incorporating Deep Learning into Fault Current Limiters (FCL)

Split-shaft wind turbines decouple the turbine’s shaft from the generator’s shaft, enabling several modifications in the drivetrain. One of the significant achievements of a split-shaft drivetrain is the reduction in size of the excitation circuit. The grid-side converter is eliminated, and the rotor-side converter can safely reduce its size to a fraction of a full-size excitation. Therefore, this low-power-rated converter operates at low voltage and handles regular operations well. However, fault conditions may expose weaknesses in the converter and push it to its limits. This paper investigates the effects of the reduced-size rotor-side converter on the voltage ride-through capabilities required from all wind turbines. Four different protection circuits, including the active crowbar, active crowbar along a resistor–inductor circuit (C-RL), series dynamic resistor (SDR), and new-bridge fault current limiter (NBFCL), are employed, and their effects are investigated and compared. Wind turbine controllers are also utilized to reduce the impact of faults on the power electronic converters. One effective method is to store excess energy in the generator’s rotor. The proposed low-voltage ride-through strategies are simulated in MATLAB Simulink (2022b) to validate the results and demonstrate their effectiveness and functionality.

Enhancing the resilience of renewable energy systems in ultra-weak grids is crucial for promoting sustainable energy adoption and ensuring a reliable power supply during disturbances. Ultra-weak grids characterized by a very low Short-Circuit Ratio, less than 2, and high grid impedance significantly impair voltage and frequency stability, imposing challenging conditions for Inverter-Based Resources. To address these challenges, this paper considers a 110 KVA, three-phase, two-level Voltage Source Converter, interfacing a 700 V DC link to a 415 V AC ultra-weak grid. X/R = 1 is controlled using Sinusoidal Pulse Width Modulation, where the Grid-Connected Converter operates in Grid-Forming Mode to maintain voltage and frequency stability under a steady state. During symmetrical and asymmetrical faults, the converter transitions to Grid-Following mode with current control to safely limit fault currents and protect the system integrity. After fault clearance, the system seamlessly reverts to Grid-Forming Mode to resume voltage regulation. This paper proposes an improved control strategy that integrates voltage feedforward reactive power support and virtual capacitor-based virtual inertia using Active Disturbance Rejection Control, a robust, model-independent controller, which rapidly rejects disturbances by regulating d and q-axes currents. To test the practicality of the proposed system, real-time implementation is carried out using the OPAL-RT OP4610 platform, and the results are experimentally validated. The results demonstrate improved fault current limitation and enhanced DC link voltage stability compared to a conventional PI controller, validating the system’s robust Fault Ride-Through performance under ultra-weak grid conditions.