Design Of Fault Current Limiter Research Articles

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.

Flux-coupling fault current limiter design for VSC DC grids

Flux-coupling fault current limiter design for VSC DC grids

Simplified Design of R-SFCL With Shunt Reactor for Protecting HTS Cable in Distribution Network

The high temperature superconducting (HTS) cable can be used as a low-voltage tie line between substations for its characteristic of high currentdensity. In this way, the remaining capacity on the low-voltage side of the transformer can be fully utilized. Moreover, The HTS cable can run in parallel with the original tie line, forming an electromagnetic ring network, to ensure the power supply of important loads. However, the short circuit current of the distribution network is large, and the electromagnetic ring network operation results in the quench of HTS cable when the short circuit fault is outside the HTS cable. It is important to ensure the safety of HTS cable under various short circuit faults. To ensure the safe operation of HTS cable in Shenzhen Power Grid, this paper built a distribution network model with HTS cable in Matlab/Simulink. The fault current and thermal process in different fault situation were analyzed. The design of fault current limiter (FCL) which is composed of the resistive superconducting fault current limiter (R-SFCL) and a shunt reactor was completed. The model of R-SFCL using R-Q method is build, and the effectiveness of the R-SFCL design is verified.

Optimized Design Method of Permanent Magnets Saturated Core Fault Current Limiters for HVDC Applications

When the fault current in high voltage direct current (HVDC) systems rises to a higher level, the DC circuit breakers will have either insufficient capacity or will require larger sizes with increased costs. Fault current limiters (FCLs) can reduce the turn-off stress and the stringent requirements on breakers, thereby also lowering their cost. The use of saturated core FCLs, which have fast response times and low power loss, is a promising approach for this issue. However, the parameter design principles for this kind of FCL has so far not been discussed in the literature. The design is often based on reactors that does not consider the transient performance. In this study, an optimized design method for permanent magnets saturated core FCLs in HVDC transmission systems, is proposed. The constraint conditions, parameter optimization and modification steps are discussed, and an optimized FCL design is obtained with the lowest cost and expected current-limiting function. Both simulations and experiments are conducted, and the results demonstrate the validation of the proposed method. Finally, a cost evaluation among main types of inductive FCLs is carried out and suggestions for scaling up saturated core FCLs to HVDC applications are given.

A Novel Three-Phase Saturable-Core Fault Current Limiter Structure

Fault current limiters (FCLs) can play an important role in providing protection of power systems against high fault current levels. This paper proposes a new three-phase structure of saturable-core FCL based on the common core for all three phases. Due to the existence of flux linkage between all three phases, the resulting electromagnetic fluxes negate each other, and therefore the inductance in the normal condition is significantly reduced. In this structure, the dc winding compensates just the imbalance of phase currents in the system. Therefore, the number of dc winding turns decreases, and consequently the induced voltage across this winding is reduced. This structure leads to a significant reduction in the volume of the core. The FCL design algorithm with the new structure is presented. In order to validate the effectiveness of the proposed FCL, simulation is carried out based on the finite-element method and a prototype is made and tested. The results prove the efficiency of the proposed method.

Design of fault current limiter using core with low initial permeability

Design of fault current limiter using core with low initial permeability

3D nonlinear transient field‐circuit modeling of inductive fault current limiters

SummaryDue to increasing levels of fault currents, fault current limiters (FCLs) are expected to play an important role in the protection of future power grids. Inductive saturable FCLs are particularly interesting due to their inherent reaction on the fault. Many different configurations have been proposed in literature. Being difficult or impossible to create accurate analytical models of some FCL configurations, the development of finite element (FE) models for inductive FCLs is required. This paper presents a 3D nonlinear transient FE modeling technique applied to two inductive FCLs, namely the so‐called open‐core and three‐leg single‐core FCLs. The models have been validated by comparing simulation results with lab measurements. Results show excellent agreement. The models constitute a valuable tool for design, optimization, and verification of inductive FCLs. Copyright © 2015 John Wiley & Sons, Ltd.

Double storey three phase saturated cores fault current limiter

A novel saturated-cores Fault-Current-Limiter (FCL) configuration is described. This FCL is based on two parallel planes of iron rectangular cores, on which three-phase coils are mounted and connected in series to the grid. Two DC coils are mounted in between the planes on perpendicular core limbs connecting the two AC planes. The DC coils are set to magnetically saturate the AC cores. The transition to three-dimensional, double-storey design enables handling three-phase symmetrical faults while offering better decoupling between the AC and DC circuits. At the same time, it shortens the AC limb lengths and enables deeper magnetic saturation levels in comparison to other saturated cores FCL designs. Hence, this FCL configuration exhibits lower insertion impedance and higher ratio of fault to nominal state impedance in comparison with other designs.

Design and Production of the ECCOFLOW Resistive Fault Current Limiter

The European project ECCOFLOW aims at a versatile resistive-type superconducting fault current limiter. For the first time, such a device will be tested at two different sites. The project partners have developed a superconducting fault current limiter design based on REBCO tapes with respect to the specifications provided by two hosting utilities. The limiter will operate at 1 kA at a rated voltage of 24 kV, and will be tested in both a busbar and a transformer feeder application. The design started with extensive investigations on the superconductor tape properties, especially with respect to the limitation behavior in all possible scenarios, and subsequent wide-range modeling of its in-grid behavior. The general integrated layout provides a limitation time of up to 1 s. The limiter is cooled using Gifford-McMahon cryocoolers to recondense the evaporated nitrogen. The present status of production and testing will be presented as well.

Hybrid Model of Quench Propagation in Coated Conductors Applied to Fault Current Limiter Design

In order to help in designing more compact fault current limiters based on coated conductors, we recently developed a hybrid model of the quench propagation in such conductors. This model combines the finite element method to study the thermal propagation and analytical calculation of heat generation. The results obtained with this model are in very good agreement with the experiments, without the need for using free parameters for adjustment. Simulations demonstrate that even slight variations of the conductor characteristics have great influence on the temperature profile along the tape during the limitation phase, due to the slow normal zone propagation velocity. 2-D parametric studies are conducted with the aim of improving the temperature uniformity by varying some characteristics of the layers of the coated conductors. 3-D simulations on a wider scale are conducted to demonstrate how the temperature uniformity could be improved further in fault current limiters by using adapted meander geometries.

Analysis of Transient Overvoltage in 220 kV Saturated Core HTS FCL

Saturated Core High Temperature Superconducting (HTS) Fault Current Limiter (FCL) is one kind of limiters that can work effectively on short-circuit current limitation. In this paper, an equivalent circuit model depending on ac coil of HTS FCL is built for voltage distribution analysis under transient overvoltage. The equivalent circuit components, such as the capacitances and inductances, are calculated by using finite element method. The voltage distribution and oscillation analysis of ac coil may benefit to the insulation design of HTS FCL.

AC Transport Loss of Coated Conductors in Anti-Parallel Arrangement

AC loss in two stacked coated conductors (CC) carrying opposite currents was investigated by experiments and numerical simulations. This arrangement is a promising option in the design of fault current limiter (FCL) because the transport current loss could be significantly lower than in the self-field configuration of one single tape. The requirements of normal-state resistance indicate that in the particular CC tape developed for FCL application the metallic stabilizing layer should be less than ~10 μm. Considering the electric strength of up-to-date insulations this leads to ~100 μm distance between superconducting layers. Our study shows how sensitively depends the loss on this quantity. Even in the case of coated conductors prepared on ferromagnetic substrate a substantial reduction of the substrate loss can be achieved by putting the tapes in close proximity with superconducting layers facing each other from minimum distance. Another factor influencing the AC loss is the variation of critical current density across the tape width. Then the comparison of calculated and measured loss data allows to assess the tape quality in a non-destructive way.

An improved design of an inductive fault current limiter based on a superconductingcylinder

This paper deals with basic designs of a fault current limiter of the transformer type whichdiffer from each other by the mutual location of a primary winding and a superconductingshort-circuited cylinder. Theoretical study of the main parameters of the differentdesigns is performed in the framework of the critical state model and shows thatthe most effective is a design in which the primary winding is divided into twosections with equal turn numbers. The sections are placed inside and outsideof the cylinder and connected in series. Such an arrangement of the windingsleads to a substantial reduction of AC losses in the superconducting cylinder, anincrease of the activation current and a decrease of the inductive reactance in thenormal regime of a protected circuit. The experimental results obtained on thelaboratory model with a BSSCO cylinder confirm the theoretical predictions.

Superconducting Fault Current Limiter Design Using Parallel-Connected YBCO Thin Films

Superconducting fault current limiters (SFCLs) are able to reduce fault currents to an acceptable value, reducing potential mechanical and thermal damage to power system apparatus and allowing more flexibility in power system design and operation. The device can also help avoid replacing circuit breakers whose capacity has been exceeded. Due to limitations in current YBCO thin film manufacturing processes, it is not easy to obtain one large thin film that satisfies the specifications for high voltage and large current applications. The combination of standardized thin films has merit to reduce costs and maintain device quality, and it is necessary to connect these thin films in different series and parallel configurations in order to meet these specifications. In this paper, the design of a resistive type SFCL using parallel-connected YBCO thin films is discussed, including the role of a parallel resistor and the influence of individual thin film characteristics, based on both theory and experimental results.

Experimental and numerical analysis of high resistive coated conductor for conceptual design of fault current limiter

Resistive superconducting fault current limiters (FCLs) using coated conductor (CC) have been developed to reduce fault current which exceeds ratings of circuit breaker in power grid. Our group has participated in the development of distribution level non-inductive winding type FCL using stainless steel-stabilized CC, as one of the 21st century Frontier R&D program. Recently, stabilizer-free CC with Hastelloy substrate was developed for FCL application. Since the CC has higher average resistivity than existing CCs with metallic stabilizer, required amount of wire can be reduced. Short-circuit tests were performed by increasing voltage applied to the small-scale FCL coil using stabilizer-free CC in sub-cooled liquid nitrogen of 65K. Experimental results of the tests were compared with numerical analysis of current limiting characteristics of the CC by using finite element method (FEM). Conceptual design of the FCL was performed using test results and was compared with FCL using existing CC in regards to current limiting characteristics.

Impact Research of Inductive FCL on the Rate of Rise of Recovery Voltage With Circuit Breakers

Fault current limiter (FCL) is expected to ease the burden on circuit breakers by limiting the fault current to a desired level. However, the burden on the circuit breakers depends not only on the interrupting current but also on the rate of rise of recovery voltage (RRRV). Based on an equivalent model of the inductive FCL and with respect to FCL terminal fault and short-line fault respectively, strict mathematical formula are presented to describe the relationship between the RRRV and the current limit factor, the stray capacitance as well as the short-line fault distance. Further, detailed computations were carried out regarding a 220-kV transmission line with three-phase-to-ground faults to fully account for the concrete impacts on the RRRV from key influential factors. The calculation results by the proposed theoretical formula in this paper coincide well with the simulations in some previous publications. The specific investigation presents analytical basis and theoretical reference for optimal parameter design of inductive FCLs and reliable selection of the interrupting characteristics of HV circuit breakers.

Magneto-Thermal Modeling of Second-Generation HTS for Resistive Fault Current Limiter Design Purposes

Coated conductors (CCs) are very promising for the design of novel and efficient resistive fault current limiters (FCLs). However, a detailed knowledge about their thermal and electromagnetic behaviors in the presence of over-critical currents is crucial for their improvement. In this context, we performed finite-element magneto-thermal modeling of CCs under over-critical current on several geometries. Accordingly, we have investigated the influence of the physical properties of stabilizer and substrate on the thermal stability to improve the high-temperature superconductor (HTS)-FCL design. All simulations were performed using COMSOL Multiphysics, a commercial finite-element package, which has a built-in coupling between the thermal and electrical equations, allowing us to compute both quantities simultaneously during the solving process. Our results allow us to determine the current threshold to achieve thermal stability of HTS FCLs made with CCs.

Verification of metal layer design for large-capacity superconducting fault current limiting elements using YBCO thin film

A superconducting fault current limiter (FCL) is one of the most attractive solutions to an increase of short-circuit current in electric power networks. The authors have studied resistive type FCLs using YBCO thin film superconductor with the patterning of superconducting and metal layers to increase the capacity of their current and voltage. A new design concept of fault current limiting element has been proposed, which has a meander-shaped gold layer on a wide I-shaped YBCO thin film. Experimental study and comparison between experimental and numerical analysis results verify the validity of the new FCL design concept.

High-temperature superconducting magnet for use in saturated core FCL

A HTS magnet system used in a saturated core Fault Current Limiter (FCL) device is described. The superconducting magnet, operating in DC mode, is used in such FCL design for saturating the magnetic core and maintaining low device impedance under nominal conditions. The unique design of the FCL poses constrains on the DC HTS magnet. A model which meets all the necessary special requirements have been realized in a compact magnet design that is optimized for its electrical characteristics while minimizing its mass and volume. The coil, made of Bi-2223 tapes, has 50000 Ampere-turns required to maintain the core in a saturated state at nominal current in the limiting circuit. Unique, nonmagnetic cryostat made of Delrin was used. Cooling of the coil has been realized by two cold heads: one double-stage head that provides a cooling power of 6 W at 20 K and a single-stage head with a cooling capability of 40W at 70 K. This magnetic system has been successfully integrated and tested in a 120 kVA FCL model. The design, characteristics and tests of this magnetic system are described.

Magneto-thermal finite element modeling of 2nd generation HTS for FCL design purposes

Coated conductors are very promising for the design of novel and efficient Fault Current Limiter (FCL). However, before considering using them in a power grid, their thermal and electromagnetic behaviors in the presence of over-critical currents need to be investigated in details. In this context, we performed finite element magneto-thermal modeling of coated conductors under over-critical current on several geometries. Accordingly, we have investigated the substrate electrical connectivity and thermal properties on the HTS-FCL behavior. All simulations were performed using in COMSOL Multiphysics®, a commercial finite element package, which has a built-in coupling between the thermal and electrical equations, allowing us to compute both quantities simultaneously during the solving process. Our simulations allowed us to formulate thresholds for the current density usable in coated HTS as well as limitation capability of a device made of these new conductors.