Fault Current Limiter Research Articles

Novel series LC resonance DC fault current limiter

Novel series LC resonance DC fault current limiter

Active Fault Current Limitation for VSC-MTDC Integrated Offshore Wind Farms Participating in Frequency Regulation

Active Fault Current Limitation for VSC-MTDC Integrated Offshore Wind Farms Participating in Frequency Regulation

Assessing High-Voltage Shore Connection Safety: An In-Depth Study of Grounding Practices in Shore Power Systems

There is growing concern regarding air pollutants (NOx, SOx, and PM) and carbon emissions from ocean-going vessels in harbor areas and the role of high-voltage shore connection (HVSC) systems in mitigating these emissions during vessel berthing. The HVSC operates as a TN grounding system in humid environments, and it needs a proper grounding design to ensure safety when faults occur. This article intends to examine the overvoltage resulting from fault currents and its implications for the safety of operators when a single line-to-ground fault takes place within the design of HVSC grounding systems. The assessment is carried out by employing actual scenarios and parameters from a container berth at Kaohsiung Harbor in Taiwan. Considering site conditions, such as the wet ground surface, human body resistance, and electric shock duration, the tolerable safe voltage level is derived using IEEE Std. 80 and IEC 60479-1. Based on the shore power system grounding architecture specified in IEEE/IEC 80005-1, an equivalent circuit model is constructed to calculate the fault currents using symmetrical component analysis. The actual touch voltages generated in various locations are analyzed under scenarios of connecting or disconnecting the equipotential bonding between the ship and the shore using neutral grounding resistor (NGR) designs. This article delves into the scenarios of electric shock that may occur during the operation of an actual container ship’s shore power system. It evaluates whether various contact voltage values exceed current international standards and verifies the grounding design and safety voltage specifications of IEEE/IEC 80005-1. According to the results of this study, the use of NGR and protective earthed neutral (PEN) conductors in HVSC is crucial. This can limit fault currents, reduce touch voltage, and ensure the safety of personnel and equipment. Therefore, ensuring and monitoring equipment conductors and adopting NGRs of appropriate sizes are crucial elements in maintaining electrical safety in HVSC systems.

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.

Multi-physics modelling and performance analysis of an air-core reactor in the framework of solid-state fault current limiters

This study presents a comprehensive multi-physics modelling of an air-core reactor operating within a solid-state fault current limiter. By utilizing an air-core reactor in the solid-state fault current limiter, it is aimed to avoid magnetic saturation and assess a conventional fault current limiting device within a contemporary fault current limiter topology. Within the employed fault current limiter topology, the air-core reactor not only limits fault current during grid faults but also carries nearly the entire network current under normal operational conditions. Therefore, the performance of air-core reactor is investigated through thermal, electromagnetic and electrostatic aspects for normal and fault conditions. A 380 V test prototype is employed to validate the coupling of reactor model and electric circuit dynamics in the simulations. Furthermore, current results of high voltage simulations are supported by PSCAD results to reveal the results accuracy. During the operation of air-core reactor in normal and fault cases, the distribution of heat originating from eddy and resistive losses was examined through convection, radiation and conduction mechanisms. Moreover, the electric field intensities affecting the reactor are obtained for different operating conditions through electrostatic analysis, whereas the electromagnetic analysis reveals the magnetic flux densities and magnetic forces acting on the reactor.

Multi-modular bridge-type FCL for enhancing FRT capability of VSC-HVDC connected offshore wind plants during AC faults

This paper presents a novel concept Multi-Modular Bridge-Type Fault Current Limiter (MMBFCL) for enhancing the fault ride-through (FRT) capability in Voltage Source Converter (VSC)-based High-Voltage Direct-Current (HVDC) systems. The MMBFCL can be directly connected to HVDC system in ac grid side without series connection of semiconductor switches and series injection transformers. Also, the limiting resistor of each module is determined based on binary arrangements to provide a multi-step insertion resistor BFCL to limit the fault current and enhance the FRT capability under different voltage sag levels. The principle operation and control system of the MMBFCL is described. Then, the performance of the MMBFCL for enhancing the FRT is validated through time domain simulations by PSCAD/EMTDC software in a HVDC integrated wind farm system. Also, the performance of the MMBFCL is compared with the single-modular BFCL (SMBFCL). Simulation results reveal that the MMBFCL compensate the voltage sag for each voltage sag levels without any over voltage at the HVDC terminal. Also, it has superior performance than SMBFCL.

Optimal overcurrent relay coordination: Balancing costs, time performance and generator placement in fault current limiter optimization

AbstractThe integration of synchronous generators (SG) to the grid will present serious problems in some instances. The increase in fault current level is one of the most crucial issues, which causes miscoordination between directional over current relays (DOCRs), in addition to putting excessive pressure on the circuit breakers. This research uses the Fault Current Limiters (FCL) to restore coordination, without changing the settings of DOCRs, by reducing the level of fault current in the grid. The main goal of this research is to find the optimal size, location, and number of FCLs at the minimum cost and with the least operation time for the relays, using Jellyfish Search Optimisation (JSO) algorithm. This can be achieved through three different approaches. The first one is optimizing the location, number, and impedance size of the FCL by minimising a cost function. The second approach involves optimizing the backup relay operation time. A combination of the two previous approaches is used as the third approach. The outstanding feature of this research is that it considers the optimal location of DG and FCL while optimizing the operation times of DOCRs, which is a new framework.

Multifaceted Functionalities of Bridge-Type DC Reactor Fault Current Limiters: An Experimentally Validated Investigation

With the ongoing expansion and interconnection of electrical power systems, alongside the rapid proliferation of renewable distributed generations (DGs), the short-circuit extent in the power grid is experiencing a significant rise. Fault current limiters (FCLs) have been introduced in an effort to address this issue, ensuring the robustness and sustainability of expensive power system components when confronted with short-circuit faults. Among the various types of FCLs, bridge-type DC reactor fault current limiters (BDCR-FCLs) have emerged as one of the most promising options. While BDCR-FCLs have shown excellent properties in limiting harmful short-circuit currents, they are also advantageous in other respects. This paper investigates the supplementary functionalities of BDCR-FCLs as a multifaceted device towards the enhancement of the quality of supplied energy in terms of total harmonic distortion (THD) reduction, power factor (PF) correction, peak current reduction for nonlinear loads, and soft load variation effects, as well as their capability to limit fault current. To this aim, the capabilities of BDCR-FCLs have been studied through various simulated case studies in PSCAD/EMTDC software V5.0.1, in addition to experimental tests considering an AC microgrid connected to a DC system. The experimental and simulation investigations verify the superior multifaceted functionalities BDCR-FCLs introduce in addition to their excellent fault current-limiting capabilities. The results show that PF improved by 6.7% and 7%, respectively, in simulation and experimental tests. Furthermore, the current THD decreased by 20% and 18% in the simulation and experiment, respectively.

Fault current limiter principle by switching magnetic circuit

AbstractSeveral types of fault current limiters have been studied so far, including superconductor based one or nonsuperconductor based one. However, it is difficult to satisfy all requirements for cost, maintainability, and current limiting performance. This study proposes another type of fault current limiter, variable transformer based one. It is supposed to be less expensive and easier to be maintained since it is based on the conventional transformer, and to be expected better current limiting performance since the magnetic circuit of the transformer is drastically changed. The magnetic circuit of the transformer is switched to be opened and to produce another one by shifting a portion of its iron core mechanically, allowing the primary and secondary electric circuit to be magnetically isolated. In that way, the electromotive force of the secondary winding could be reduced so that the secondary current could be limited. The prototype based on this concept was designed and built up, and its stational performance has been investigated. As a result, it was confirmed that the prototype shows good current limiting performances identical to the results of the previous FE analysis. Furthermore, the prototype was connected to the operating mechanism to investigate the transient performances, and as a result, satisfying current limiting performances are confirmed

The Principles of Controlled DC-Reactor Fault Current Limiter for Battery Energy Storage Protection

The significance of battery energy storage systems (BESS) technology has been growing rapidly, mostly due to the need for microgrid applications and the integration of renewables. Relevant to the importance of utilization of BESS in microgrids, the protection of the BESS during microgrid faults has become a concern too. The short-circuit in a microgrid cause over-current for all of the integrated sources. BESS, as one of the sources in the microgrid, is heavily influenced by fault occurrence. The overcurrent can easily damage power electronic converter switches, battery management systems (BMS), and damage battery banks. Fault current limiters (FCLs) are appropriate protection devices that have been massively studied. This paper proposes a controllable reactor fault current limiter (CRFCL) to protect the BESS against fault currents. The proposed CRFCL can control the fault current value supplied by BESS during a fault condition as a current regulator. It is realized by means of the operation of solid-state switches and series DC reactor behavior. The main achievement of CRFCL is the protection of BESS against fault currents without delay. The simulations of the proposed structure are carried out in a MATLAB/SIMULINK platform, and they are confirmed and validated by experimental test results.

A novel hybrid magnetic material based on three-phase saturated core fault current limiter

Installing a three-phase saturated core fault current limiter (TSFCL) is an effective method to limit the increasing short-circuit current in high-voltage alternating current (HVAC) systems. However, the traditional TSFCL uses silicon steels as its working material for the iron core, resulting in poor current-limiting effects, requiring a large DC excitation current, and having a slow response speed. Nanocrystalline alloys have advantages such as a lower saturation point, higher permeability in the unsaturated zone, and a steep B–H curve, making them highly suitable for TSFCL’s applications. However, their poor capability which withstands fault hindered their large-scale commercialization. Therefore, this paper proposes a novel hybrid magnetic material based on TSFCL (HMTFCL), where the materials of the working limbs are replaced by nanocrystalline alloys. Compared to TSFCL, the DC excitation current of HMTFCL decreases by 60.5%. And, the HMTFCL reduces the peak short-circuit current by 23%. Last, the magnetic flux intensity inside the working limb of HMTFCL is reduced to zero more quickly.

Short-circuit current-limiting scheme with fast switch fault current limiter on 750kv autotransformer

This paper proposes different short-circuit current limiting schemes using FSFCL on autotransformers, derives the equivalent models of installing the fast switch fault current limiter at different positions of autotransformers, and simulates the current limiting effect of each scheme using PSASP. The simulation results show that the fast switch fault current limiter on the side near the neutral point of the common winding of the autotransformer is the optimal scheme for comprehensive parameters.

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.

Optimal Allocation of Fault Current Limiters in Power Systems: A Comprehensive Review

Background: This paper delves into the potential of Fault Current Limiters (FCLs) as a transformative technology within power systems. FCLs assume a pivotal role in streamlining network expansion efforts, sustaining fault current levels, and augmenting the overall performance of power systems. The classification of FCLs is outlined, encompassing superconducting FCLs (SFCLs), Solid-State FCLs (SFCLs), and non-superconducting FCLs (Non-SFCLs). Objective: The core of this study lies in an exhaustive review of relevant literature, with a keen focus on optimal allocation strategies for FCLs. The primary objective of this paper is to function as an all-encompassing reference for both researchers and engineers, providing optimal FCL allocation studies. Method: this paper discusses various techniques for the optimal allocation of FCLs within power systems. These allocation methods are categorized based on multiobjective functions such as cost, fault current reduction, stability, protection coordination, reliability, and power quality. Results: This search presents an overview of the FCL survey structured around key components, including objective functions, design variables, constraints, optimization methods, network types, FCL types, and research contributions. Conclusion: This work aims to empower professionals in the field with a robust understanding of FCL allocation, ultimately contributing to the efficient and sustainable evolution of power systems. FCLs represent a promising technology for enhancing the performance and reliability of power systems, and this paper serves as a comprehensive resource for those interested in optimizing their allocation within these systems.

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.

Inexpensive short-circuit current limiter and switching device based on one commutation circuit for a three-phase system

The escalating levels of fault currents resulting from short circuits, particularly in the context of distribution generators, have presented a critical need for the widespread implementation of fault current limiters (FCLs) in power systems. Despite their evident advantages, the extensive adoption of FCLs has been hindered by the high production costs associated with these devices. To address this challenge, a comprehensive study was conducted to develop a cost-effective FCL tailored specifically for three-phase power systems. This paper proposes a novel approach based on a single commutation circuit for the FCL and offers detailed insights into the construction of the FCL circuit, with a particular focus on efficient current interruption. Additionally, the study comprehensively discusses the logic controller and measurement system employed in conjunction with the proposed FCL, ensuring precise fault detection and rapid response to disturbances within the power grid. The integration of an artificial zero-crossing circuit within the FCL design further enhances its capability to limit short-circuit currents proactively, even before the occurrence of the first peak, thereby bolstering overall system reliability and stability. The study's significant contribution lies in achieving cost-effectiveness through the simplicity of the FCL's design, eliminating the need for extensive upgrades to various network components.

Research on the dynamic characteristics of the electromagnetic repulsion mechanism of a self-driving fault current limiter

A fault self-driven current limiter is proposed in the paper, which uses a special fault current direct-driven electromagnetic repulsion mechanism to realize the first half-wave of the fault current over the zero point into the current-limiting reactance. The paper analyzes the working principle of the self-driven electromagnetic repulsion mechanism, establishes the equivalent model of the mechanism, and simulates the dynamic characteristics of the electromagnetic repulsion mechanism through the calculation of the double-layer iterative algorithm in time and space. The LC oscillation loop test platform is built, and the stroke–time curve of the prototype is measured. In the test, the prototype is driven by a 3 kA current, and the first half-wave stroke (FHWS) is 3.55 mm past the zero point, which is consistent with the simulation and test results. The effects of structural parameters such as the radius, thickness, and number of turns of the self-driven electromagnetic repulsion mechanism on the dynamic characteristics of the electromagnetic repulsion mechanism are investigated, and it is found that the first half-wave stroke can be significantly improved by increasing the number of turns and outer diameter of the coil. The optimum height of the dynamic repulsion coil is approximately 3 mm.

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.

Transient performance improvement of DFIG‐based wind farm by H‐bridge fault current limiter

AbstractDespite the unique advantages a doubly fed induction generator (DFIG) offers to the grid‐integrated renewable energy systems, they have a limitation of being susceptible to grid fault as their stator windings are directly connected to the grid. The fault current limiters (FCLs) provide a sustainable solution by enhancing the fault ride‐through capability and thus it improve the transient performance of a DFIG. In this work, a multi‐inductor‐based H‐bridge fault current limiter (HBFCL) is proposed to augment the transient performance of a DFIG. The operational efficacy of the HBFCL is evaluated through the administration of both symmetrical and asymmetrical fault scenarios. The effectiveness of the HBFCL is further investigated by comparing the performance of the HBFCL with that of the bridge‐type series dynamic braking resistor (BSDBR). Both the graphical and numerical interpretations of the simulation result assert that the HBFCL improves the transient performance of a DFIG‐based wind farm and outweighs the performance of the BSDBR in all aspects.