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The intensive development of hydrogen technologies has made very promising applications of one of the cheapest and easily produced bulk MgB2-based superconductors. These materials are capable of operating effectively at liquid hydrogen temperatures (around 20 K) and are used as elements in various devices, such as magnets, magnetic bearings, fault current limiters, electrical motors, and generators. These applications require mechanically and chemically stable materials with high superconducting characteristics. This review considers the results of superconducting and structural property studies of MgB2-based bulk materials prepared under different pressure–temperature conditions using different promising methods: hot pressing (30 MPa), spark plasma sintering (16–96 MPa), and high quasi-hydrostatic pressures (2 GPa). Much attention has been paid to the study of the correlation between the manufacturing pressure–temperature conditions and superconducting characteristics. The influence of the amount and distribution of oxygen impurity and an excess of boron on superconducting characteristics is analyzed. The dependence of superconducting characteristics on the various additions and changes in material structure caused by these additions are discussed. It is shown that different production conditions and additions improve the superconducting MgB2 bulk properties for various ranges of temperature and magnetic fields, and the optimal technology may be selected according to the application requirements. We briefly discuss the possible applications of MgB2 superconductors in devices, such as fault current limiters and electric machines. [ABSTRACT FROM AUTHOR]

The inherent constraints of grid‐forming converters affect their ability to maintain voltage source characteristics within a specific operational range. In response to these limitations, ongoing pilot projects involving grid‐forming technology have adjusted their current thresholds up to three times the rated current, significantly exceeding the traditionally threshold of 1.2 times the rated current. This paper aims to investigate the effects of current thresholds on the dynamic responses of grid‐forming converters under large disturbances, with the intention of identifying an optimal current threshold that meets the grid's demands for maintaining voltage source characteristics and overall stability. A novel power angle relationship is introduced, integrating current limits and anti‐windup voltage controls into the equivalent circuit models of these converters. Analytical expressions for stable and unstable equilibrium points are derived, improving insights into the converters' dynamic behaviour and their resilience to phase jumps across various current thresholds and short‐circuit ratios. Findings indicate that higher current thresholds substantially improve phase jump limits and withstand capabilities. The paper concludes with proposed configurations and optimization strategies for current thresholds, all supported by experimental validation. [ABSTRACT FROM AUTHOR]

This research paper presents a new approach to address power quality concerns in microgrids (MGs) by employing a superconducting fault current limiter (SFCL) and a fuzzy-based inverter. The integration of multiple power electronics converters in a microgrid typically increases total harmonic distortion (THD), which in turn results in power quality issues. Moreover, the intrinsic variability of solar and wind power sources gives rise to fluctuations in power generation, which consequently leads to power oscillations and voltage sag within microgrids that rely on renewable energy. This research paper introduces a technical approach to achieve power balance in renewable-based microgrids (MGs) by utilizing a fuzzy logic-controlled (FLC) pulse width modulation (PWM) inverter. The Microgrid (MG) consists of a hybrid photovoltaic (PV) system and a wind energy conversion system (WECS) that utilizes a permanent magnet synchronous generator (PMSG). The system employs an optimal torque-controlled maximum power point technique (MPPT) algorithm to optimize power output. The battery energy storage system (BESS) is employed to facilitate power provision during critical scenarios or to ensure a stable power output for fluctuating loads. The SFCL is utilized as a device for voltage compensation in cases of voltage sag incidents. The effectiveness of the suggested control strategy is assessed by performing a comparative analysis of total harmonic distortion (THD) in the load voltage, with and without the utilization of a SFCL. The results suggest that the incorporation of an FLC inverter-SFCL-BESS system effectively mitigates THD and voltage sag, according to the requirements set by the IEEE 519 standards. The research study is carried out by using the MATLAB/SIMULINK software environment. [ABSTRACT FROM AUTHOR]

Photovoltaic power plant (PVPP) has increased importance among renewable energy sources due to their ability to be connected more easily to a modern power grid. However, the reliability and stability operation of a grid-connected PVPP system is very important to ensure even during grid faults. In this study, a capacitive bridge fault current limiter (CBFCL) using a machine learning (ML) method is applied to enhance the fault ride-through (FRT) capability of a grid-connected PVPP system. Three different protection methods called DC chopper, CBFCL, and DC chopper + CBFCL are designed to prevent the harmful effects of overcurrent that occurs during grid faults to protect the grid-connected PVPP system. The ML algorithm can be trained on historical data to predict optimum control parameters based on real-time conditions such as normal and fault operations of the grid-connected PVPP system. An ensemble classification algorithm has the best results among the four classification algorithms in machine learning methods. The ensemble classification algorithm is separately implemented into the control systems of three protection strategies. Bagged Trees and Subspace KNN classifiers in ensemble classification methods have obtained an impressive accuracy of 98% in ML classification methods. The simulation results illustrate that the DC chopper + CBFCL based ensemble provides the best protection for the grid-connected PVPP system compared to other protection systems. [ABSTRACT FROM AUTHOR]

Despite many advantages of distributed generation (DG), it can have adverse effects on the network protection coordination by raising the short-circuit level of buses. This issue can often be resolved by incorporating fault current limiters (FCLs) that are properly located and sized in the network. We propose an efficient method to simultaneously attain the optimal location and size of DG and FCL units for protection coordination of overcurrent relays and cost reduction in a distribution network. The proposed method involves three stages. First, two separate objective functions are derived, representing the operation times of relays and the network costs associated with the installation of DGs and FCLs and system losses. The Strength Pareto Evolutionary Algorithm 2 (SPEA-2) is then used for finding a Pareto-optimal solution set for the interrelated multiobjective problem at hand. Finally, the k-means clustering method is utilized to group the best solutions. In contrast to the conventional weighted sum (WS) method, the proposed method is more computationally efficient while being capable of treating complex networks with non-convex Pareto front solutions. These features are demonstrated by implementing the proposed approach in the 14-bus IEEE test grid and comparing the results with those obtained using the conventional WS method. [ABSTRACT FROM AUTHOR]

In this paper, a novel high temperature superconducting (HTS) thin film device as planar levitator and fault current limiter is firstly proposed and tested. Nowadays, planar magnetic levitation (maglev) levitator (PML) employed in planar maglev system is a promising high-precision positioning mechanism for modern high-end industrial fields, due to the attractive features of noncontact, zero friction, high precision, light weigh, simple structure, high reliability, fast response and fewer interfering factors, etc. In contrast to other maglev technologies, HTS maglev technology has the advantages of passive self stabilization levitation, light weight, high vacuum gain, simple structure, energy saving and no electromagnetic pollution, etc. Thus, the PML fabricated by HTS thin film can further simplify the system control strategy and improve operation efficiency. In this paper, we designed and fabricated the double sided YBa2Cu3O7-x thin film based PML and analyzed its levitation force characteristics. Besides, we also tested its fault current limiting performance, which can be employed to limit the fault current in the planar maglev system. It can be found from the experimental results that, the HTS-PML can offer the levitation force more than 400 kN/m3 and 100 N/kg, meanwhile, it can also generate the quench resistance more than 15 Ω to limit the fault current effectively. This work is perspective for the future planar maglev applications, to improve the system compactness, stability, reliability, miniaturization and lightweight with multifunctional integrated design. [ABSTRACT FROM AUTHOR]

The occurrence of short-circuit faults in AC/DC microgrids gives rise to exceptionally high currents with rapid escalation, particularly in DC feeders where current zero-crossing is absent. This study introduces a comprehensive design procedure for a solid-state breaker tailored to address this challenge. A key innovation of the proposed solid-state circuit breaker lies in the incorporation of a current limiter reactor, which effectively constrains the current flow in both the load commutation switch and main breakers. Additionally, the inclusion of a resistive branch diminishes energy dissipation in the main breakers, safeguarding them against voltage stress. Consequently, the operational efficiency of the breaker is significantly enhanced, ensuring swift and efficient fault current interruption in vulnerable AC/DC microgrid scenarios. The efficacy of the proposed solid-state breaker was rigorously examined through analytical studies, and the results were validated using MATLAB/Simulink simulations. This breakthrough design represents a promising advancement in the realm of microgrid protection, offering a robust solution for mitigating the impact of short-circuit faults in AC/DC systems. [ABSTRACT FROM AUTHOR]

The 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. [ABSTRACT FROM AUTHOR]

In permanent magnet synchronous motor drives, d-q current errors are examined using hysteresis controllers. The inverter is switched based on the hysteresis controller responses, to limit current errors, thereby reducing current ripple. But, due to the faster current dynamic characteristics, switching the current errors within the hysteresis band becomes difficult. This results in d-q current ripples and harmonics. In this paper, two current error-limiting schemes are proposed. In the first scheme, current errors are switched within the band using additional control parameters (dynamic response of q-axis current), to select the control space vector from a switching table. Whereas in the second scheme, a duty ratio regulator is designed to achieve minimum q-axis current error. The proposed works are simulated in MATLAB/Simulink and verified through experimentation. Since the current ripple and harmonics are also reduced, the thermal impact of these performance parameters on the power inverter is also studied. [ABSTRACT FROM AUTHOR]

Several 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 [ABSTRACT FROM AUTHOR]

In recent years, with the rapid development of high-voltage flexible direct current (DC) transmission systems, more and more multi-port high-voltage DC systems have been successfully put into operation. Therefore, the number of connecting ports on the DC bus is gradually increasing, which necessitates higher requirements for clearing fault current. To better protect the DC power grid, this paper integrates a DC fault current limiter with a multi-port DC circuit breaker. This article proposes a modular cascaded multi-port hybrid DC circuit breaker topology. It also elaborates on the topology structure, working principle, and control program under three different fault conditions. It completes the theoretical derivation and analysis of the circuit breaker fault isolation process, as well as the parameter design of the core components. Finally, a model is established in PSCAD/EMTDC for simulation verification. The application performance of the circuit breaker in four-terminal DC systems is studied and analyzed, and the current-limiting effect of the multi-port DC circuit breaker proposed in this article is demonstrated. In addition, the disconnection performance and energy consumption of the arrester have been improved to a certain extent, which has good feasibility and economy. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This research paper represents the estimation and reduction of eddy current loss in a Magnetic Fault Current Limiter (MFCL). The nonlinear model of the device is established using electromagnetic coupled circuit supported by Finite Element Model. The current limiting performance of the MFCL is investigated by simulation study as well as laboratory testing. It is further observed that a significant amount of eddy current loss takes place inside the core and permanent magnet of the device. Different methods (shorting ring, lamination of permanent magnet and variation of magnet length) are proposed to reduce the eddy current. The advantages and disadvantages of these methods are discussed. Some design modifications are also proposed to minimize the temperature rise caused by the eddy current. [ABSTRACT FROM AUTHOR]

Various methods are used to reduce fault currents in fault situations occurring in power systems. In this study, a developed single-phase power electronics-based solid-state fault current limiter is presented. The proposed single-phase solid-state fault current limiter is designed as preliminary prototype of the three-phase low voltage solid-state fault current limiter. The maximum current and voltage capability of the fault current limiter is 16 A and 480 V. This limiter works according to the principle of series and parallel resonance. In normal operation, the current passes through the inductance and capacitor, which are in series resonance. Thus, extra voltage drops and power loss in the system are prevented. In the event of a fault, the limiter switches to parallel resonance, and its impedance increases. Therefore, the fault current is decreased. The developed circuit and control algorithm reduces the first peak of fault current with a rather high percentage by comparison with the fault current without fault current limiter. In addition, the amplitude of current oscillation is decreased, and the current is recovered in a short time because the control algorithm determines the fault start and end time fast. The effect of the limiter is demonstrated with the simulation results in Matlab/Simulink. The simulation results are verified with the application study carried out in the laboratory environment. The fault current reaches up to 58.5 A in case of fault current limiter is not used, whereas the developed fault current limiter suppresses the current to around 9 A. The value of maximum fault current decreases to 15% according to the non-fault current limiter used situation. In the study, detailed application notes of the limiter circuit are shared. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Coreless fault current limiter with variable series reactor is an emerging technology for limiting the amplitude and shortening the fault duration in the power network with simple and reversible operation. The device includes two coaxial, coreless reactors with axial mobility to vary and increase the effective inductance of the network during the short circuit fault. The reactors are automatically returned back to their initial position after the fault is cleared, with minimal net inductance. This paper aims to analytically describe the electromagnetic theory and validate the functionality of the device. For this purpose, the resistance and inductance of the device are first computed at normal condition via the basic theory of engineering electromagnetics. Next, the respective electromechanical performance characteristics such as force, positional displacement of the reactors, and the effective inductance are calculated at the faulty condition. For verification purposes, analytical results are compared against the finite element model. [ABSTRACT FROM AUTHOR]

This paper proposes a new adaptive nonlinear extended state observer‐based model predictive controller (ANLESO‐MPC) for residual current compensation (RCC) inverters to compensate fault characteristics in resonant grounded power systems (RGPSs). In the proposed scheme, the adaptation feature is used to adapt the adjustable inductor appearing in the dynamical model of RGPSs by satisfying the desired fault current compensation requirement which in turn will ensure the resonance condition. Since the adapted parameter is used in the control signal, the ANLESO‐MPC offers robustness against parameter sensitivity. The neutral voltage is considered as a disturbance and the change in this voltage as an extended state to estimate this disturbance while incorporating the adapted parameter so that the adaptive nonlinear extended state observer (ANLESO) provides robustness against disturbances. Finally, the model predictive controller (MPC) is designed for the RCC inverter utilizing estimated disturbances and adapted parameters to fully achieve the fault current compensation. The performance of the controller is evaluated using simulations in MATLAB/Simulink and OPAL‐RT real‐time platforms under varying fault impedances as the fault characteristics change with variations in the fault impedance. Results are also compared with a conventional MPC where the proposed ANLESO‐MPC seems more effective to compensate fault characteristics. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Subsequent commutation failure in high-voltage DC transmission systems seriously emphasizes the safe and stable operation of power systems. Via analyzing the mechanism of commutation failure and the principle of voltage-dependent current order limiter (VDCOL), this paper proposes a dynamic nonlinear VDCOL control strategy based on the Taylor expansion of DC voltage for suppressing subsequent commutation failure. To solve the problem of fluctuating DC current command value caused by a large drop in DC voltage, this paper constructs a nonlinear VDCOL control that can be dynamically adjusted according to the AC bus voltage level, and Taylor expansion of DC voltage is used to obtain its first-order and second-order differential components. Different scales of differential elements are chosen to predict the DC voltage compensation value while balancing sensitivity and accuracy. The compensated DC voltage, used as the starting voltage of VDCOL, is input to the VDCOL control constructed in this paper to suppress the subsequent commutation failure of the transmission system by reducing the fluctuation of the current command value. Finally, the standard test model of HVDC is established based on the actual parameters, and the simulation results show that the Method proposed in this paper has an effective suppressing effect in the case of single-phase or three-phase faults of different severity and is conducive to the restoration of the system power transmission. [ABSTRACT FROM AUTHOR]

High 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. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to clarify voltage sourced converter's (VSC's) influence rules on the alternating current (AC) short-circuit current and identify the key factors, so as to propose the short-circuit current suppression strategy. Design/methodology/approach: This paper investigates the key factors which impact the short-circuit current supplied by the VSC based on the equivalent current source model. This study shows that the phase of the VSC equivalent current source is mainly affected by the type of fault, whereas the amplitude is mainly decided by the control mode, the amplitude limiter and the electrical distance. Based on the above influence mechanism, the dynamic limiter with short-circuit current limiting function is designed. The theoretical analysis is verified by simulations on PSCAD. Findings: The short-circuit current feeding from VSC is closely related to the control mode and control parameters of the VSC, fault type at AC side and the electrical distance of the fault point. The proposed dynamic limiter can make VSC absorb more reactive power to suppress the short-circuit current. Research limitations/implications: The dynamic limiter proposed in this paper is limited to suppress three-phase short-circuit fault current. The future work will focus more on improving and extending the dynamic limiter to the fault current suppression application in other fault scenarios. Practical implications: The research results provide a reference for the design of protection system. Originality/value: The key influence factors are conducive to put forward the measures to suppress the fault current, eliminate the risk of short-circuit current exceeding the standard and reduce the difficulty of protection design. [ABSTRACT FROM AUTHOR]

The increase in distribution power demand and distributed generation may lead to a rise in power substation fault current levels. One possible solution to this problem is the use of a solid-state fault current limiter (SS-FCL). In this context, this paper proposes the concept of a bridge-type solid-state device switching an air-core reactor as an SS-FCL topology. The overvoltage protection system details are presented, along with an explanation of the fault detection algorithm control's principle. An experimental setup is designed to evaluate various events in addition to the short-circuit, such as load-steps, harmonic loads, motor startups, and transformer's inrush. Fault current is detected within one millisecond, with a total reduction of 42%. The overvoltage protection system clamped the peak voltage across the semiconductor switch and kept the dV/dt below the maximum stipulated. The load input tests showed a proper limiting operation and provided that the device is within the parameterization range. [ABSTRACT FROM AUTHOR]

The algorithms of the present generation of practical differential relays are based on two methods. The first method is based on the ratio of the harmonic content of the differential current, and the second one is based on the length of the time interval between the zero‐crossing points of the differential current, called the gap‐detection method. However, these methods suffer from the installation of the fault current limiters (FCLs) in the power system and current transformer (CT) saturation phenomenon. This paper deals with a simple practical method for differential relays to secure their performance. In the suggested method, a classifying algorithm is used to categorize the input signal of the relay and then the best method of the present generation of differential relays is employed. By this simple decision, the method takes the advantage of harmonic‐based and gap‐detection methods, while avoiding their drawbacks. To prove the robustness of the suggested method, a test bench with a resistive solid‐state fault current limiter (SSFCL) is implemented and examined in different situations. The results validate the consistency and the accuracy of the modified technique not only in the absence and the presence of the FCL but in the case of CT saturation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The limiter in grid-connected inverter control may cause sustained oscillation in the system. The large-signal impedance model is provided since the traditional small-signal impedance model cannot accurately describe the characteristics of the limiter. In this paper, there are three established large-signal impedance models of grid-connected inverters that take into account the limiter in the phase-locked loop (PLL), the limiter in the current control loop and the limiter in the pulse width modulation (PWM). Based on the established models, the influences of these different limiters on the output impedance characteristics of the grid-connected inverter are discussed. Furthermore, the stability of the system considering the influence of different limiters is analyzed and the oscillation frequency and amplitude of the system are predicted. The simulation verifies the accuracy of the large-signal impedance model and the predicted oscillation frequency and amplitude. [ABSTRACT FROM AUTHOR]

Due to the demand for eco-friendly energy, distributed energy resources (DERs) using renewable energy have increased. The increase in DER has caused the power system to become more complex and caused problems in the protection system. Typical problems include an increase in fault current and a problem that causes malfunction of the overcurrent relay (OCR). If the fault current increases and exceeds the capacity of the existing protection devices, it may lead to a large blackout. The most effective way to limit the fault current is to install a superconducting current limiter (SFCL). The installation of SFCL and system penetration of DER both affect OCR operating characteristics. In this paper, a simulated power distribution system is constructed and OCR malfunctions caused by DER penetration and SFCL installation are analyzed. [ABSTRACT FROM AUTHOR]

The presence of high short-circuit currents (200–300 kA) in autonomous and generator power systems of low and medium voltage classes, causing a decrease in the switching resource of switching facilities, necessitates the search for ways of limiting the current. The paper proposes a solution to this problem: a semiconductor current-limiting device based on a DC chopper, a DC-to-DC converter. This devices' features are its low dimensions and losses during typical operation. Semiconductor elements can be arranged quite compactly due to the lack of radiators for cooling, since the cooling process—taking into account the short duration of the current limitation process—is not efficient. The choice of semiconductor devices takes into account the short duration of the current load, as a result of which the temperature of the semiconductor structure does not exceed its permissible value. This paper presents a method for calculating the parameters of semiconductor devices, taking into account the current load as well as adjusting the magnitude of current limitation to a value that can be disconnected by switching devices. The short-term mode of operation of the power semiconductor device with current regulated by the frequency and duty cycle of its operation makes it possible to facilitate the required current limitation in the circuit for the subsequent fault clearance with a typical electrical device. The problem of overcurrent of one of the elements of the limiter is noted, which requires special attention to ensure that the semiconductor device is not overheated. This paper also presents the principle of current limitation, summarizes the results of experimental studies, and analyzes the presented capabilities of a semiconductor current limiter. [ABSTRACT FROM AUTHOR]

Reliable and economic protection of DC grids against fault currents is the main challenge for the development of voltage source converter-based DC grids. Application of fault current limiters (FCLs) can limit the rapid increase of fault current and reduce the DC circuit breaker (DCCB) requirements to isolate the fault. This article reports a bidirectional solid-state FCL (BSSFCL) to protect the DC lines against DC short circuit fault. In addition, it can limit fault current in both directions. The circuit and principle operating of the proposed BSSFCL are presented. Then, the current limiting performance of the proposed BSSFCL is analyzed and its parameter design requirements are presented. Finally, the performance of the proposed BSFFCL is compared with that of the RL-current limiting circuit (RL-CLC), mutual inductance-type FCL (MIFCL), and restive mutual-inductance solid-state FCL (RMI-SSFCL). The numerical analysis and simulations were done using the PSCAD/EMTDC software. It was found that, the BSSFCL could effectively enhance the breaking capability of DCCBs. Moreover, it outperforms the RL-CLC, MIFCL, RMI-SSFCL in terms of the fault current limiting, the fault clearing time and metal oxide arrester (MOA) energy absorption of DCCBs. [ABSTRACT FROM AUTHOR]

High voltage direct current transmission based on a modular multilevel converter (MMC-HVDC) is an effective method to solve the grid connection of the new energy. A DC fault is an issue that must be solved for MMC-HVDC. This paper proposes a protection scheme for HVDC converters to quickly suppress DC fault current without increasing the operation loss. By employing a bypass arm in conjunction with a switch-type zero-loss current limiter (SZCL), most of the DC current in the bridge arm flows through the bypass arm so the fault current of the power devices is reduced. There are a number of main advantages of this scheme. The fault isolation time can be greatly shortened, the cost of the system is effectively reduced, the steady-state operation loss of the system does not increase, the operation of the AC-grid can be maintained stably when a DC fault occurs, and the overcurrent impulse to the AC-grid is reduced. The proposed scheme is applicable to two-terminal systems and the DC grid, especially for faults at the converter outlet of the DC grid. Simulation results using PSCAD/EMTDC show the superiority of the proposed scheme when compared with other schemes and a comparison of the costs shows the feasibility of the proposed scheme in practical applications. [ABSTRACT FROM AUTHOR]

Increasing short-circuit fault currents is one of the critical challenges in microgrids (MGs). In this paper, a novel AC/DC fault current limiter (ADFCL) is proposed to limit short circuit current of both DC and AC sides in hybrid AC/DC MGs (ADMGs). It includes two AC and DC ports, installed between AC MG (ACMG) and DC MG (DCMG). Also, it has only one common limiting resistor for limiting short circuit current in faulty MG without affecting the performance of the healthy MG. The proposed ADFCL power circuit, its principle of operation and control system are presented. Then, the feasibility of the ADFCL is verified by simulation in PSCAD/EMTDC environment and finally, a prototype is built. Both experimental and simulation results reveal that the ADFCL can limit the faulty MG by using only one limiting resistor without affecting the performance of the healthy one, which reduces the cost of using FCL in ADMGs. [ABSTRACT FROM AUTHOR]

The authors deal with design and analysis of an air‐core electromagnetic fault current limiter (FCL) with rotary motion. The proposed device is characterised by a simple structure, fast operating speed and reversible operation. It consists of two movable concentric air core spherical reactor rings (i.e. inner and outer rings) with variable mutual angular displacement. At normal condition, reactors are approximately aligned, and subsequently, the effective inductance/impedance of the equipment and the respective voltage drop are low. At faulty conditions, the short circuit current exerts a repulsive rotary electromagnetic torque on the reactors, which results in a fast and steady increase of the reactors angular displacement. During this process, the effective inductance of the equipment rapidly rises up to a level that effectively limits the short circuit current. To determine the effectiveness of the proposed topology in limiting the network's fault current, the inductance profile of the proposed rotary FCL and the respective fault current characteristic are compared with similar case studies (a) with linear FCL and (b) without FCL. The analysis is carried out via a finite element (FE) and supported via analytical and theoretical discussion. Finally, a down‐scale prototype of the proposed FCL was built and tested to verify the functionality of the device in the lab environment. [ABSTRACT FROM AUTHOR]

The incorporation of foreign nanostructure oxide phase into the YBa 2 Cu 3 O 7 - d ( Y 123 ) superconductor material is capable of producing trapping sites and upgrading the property of flux pinning (FP). Bulk ceramics with porosity around 19% ± 1% having a nominal composition Y 123 + x Dy 2 O 3 are prepared via the solid-state reaction method. Dy 2 O 3 nanoparticles ( Dy 2 O 3 - NPs ) with an average size of about 20 nm and content x = 0.0, 0.1, 0.2, and 0.5 wt% are considered in this study. The structure, microstructure, magnetic susceptibility, electrical properties, and fluctuation-induced conductivity were investigated in detail. The X-ray diffraction (XRD) patterns showed the existence of YBa 2 Cu 3 O 7 - d with orthorhombic structure as a major phase. The microstructural examination using scanning electron microscope (SEM) and energy-dispersive X-ray (EDX) spectroscopy showed that Dy -rich nano-agglomeration segregated at the grain boundaries or on the surface of Y123 grains. The volume fraction of superconductor grain ( f sg ) and Josephson energy coupling (E j) were extracted from AC susceptibility versus temperature measurements. From log–log plots of the excess conductivity versus, the reduced temperature and using the Aslamazov–Larkin model, we assessed the crossover temperatures between different regimes of conductivity, the effective thickness of the 2D layer system (d), the coherence length ( ξ co ), the penetration depth ( λ o ), the critical current density ( J c (0) ) as well as the upper and the lower critical magnetic fields ( B c2 (0) and ( B c1 (0) ) at zero kelvin for all the ceramics. ξ co and λ o decreased, while J c (0) , B c2 (0) , and B c1 (0) increased with Dy 2 O 3 -NPs addition up to 0.2 wt% results in better flux trapping. The highest values of B c 1 (0) , B c 2 (0) , and J c (0) are found to be equal to 2.6 Tesla, 120.6 Tesla, and 65.64 × 103 A/cm2, respectively. The inclusion of a suitable amount of Dy 2 O 3 -NPs into the YBa 2 Cu 3 O 7 - d superconductor is an encouraging way for developing material with good superconducting performances for practical applications such as the second-generation HTS technologies for power transmission and fault current limiters. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) resources' installation has numerous advantages in distribution feeders nonetheless they may threaten the selectivity and reliability of protective installations. All proposed schemes including employing distance or directional overcurrent relays, mathematics methods, online overcurrent relay settings change, fault current limiters, PV disconnection after fault, computing optimal installation location of PVs, and the others are too costly or complex or inefficient in PV-penetrated feeders. This paper proposes a new central processor unit to create a smart overcurrent relay and prohibit protection blinding, nuisance tripping, unwanted tripping, and synchronous tripping of overcurrent relay in a PV-penetrated distribution feeder. Firstly, the processor consists of four layers of the multi-agent system, which receives information on the relays and sensed current via the grid. Secondly, each agent is responsible to prevent a separate maloperation event and scrutinizing the input information. Finally, it directs the manipulated commend to the respective breaker if relay has acted incorrectly. Overcurrent relays become smart and miscoordination and maloperation problems are corrected completely by implementing the proposed processor. The proposed scheme is fast, offline, inexpensive, independent of the fault and PV installation location, type and impedance of the fault, and PV capacity. The results indicate the proposed plan has acted successfully with 100% efficiency in all scenarios. [ABSTRACT FROM AUTHOR]

The extensive application of power transfer through high-voltage direct current (HVDC) transmission links in smart grid scenarios is due to many factors such as high-power transfer efficiency, decoupled interconnection, control of AC networks, reliable and flexible operation, integration of large wind and photovoltaic (PV)-based off-shore and on-shore farms, cost-effectiveness, etc. However, it is vital to focus on many other aspects like control, protection, coordinated operation, and power management to acquire the above benefits and make them feasible in real-time applications. HVDC protection is needed to focus further on innovative and devoted research because the HVDC system is more vulnerable to system faults and changes in operational conditions in comparison to AC transmission because of the adverse effects of low DC-side impedances and sensitive semi-conductor-based integrated power electronics devices. This paper provides a comprehensive review of the techniques proposed in the last three decades for HVDC protection, analyzing the advantages and disadvantages of each method. The review also examines critical findings and assesses future research prospects for the development of HVDC protection, particularly from the perspective of smart-grid-based power systems. The focus of the review is on bridging the gap between existing protection schemes and topology and addressing the associated challenges and issues. The aim is to inform power engineers and researchers about potential research avenues to tackle the challenges in HVDC protection in smart-grid-based power systems. [ABSTRACT FROM AUTHOR]

The intermittent access of renewable energy sources leads to a significant increase in fault short‐circuit currents in power grid. DC superconducting fault current limiters (SFCL) can limit short‐circuit currents in flexible DC transmission systems, which work in combination with direct current circuit breaker (DCCBs) to protect the grid system effectively. However, for the parameter design of DC superconducting fault current limiter (DCSFCL), it is difficult to balance the economics of the device and its adaptability to different fault situations. In this paper, a cross‐mapping design methodology for the DCSFCL is proposed and applied in the Nan'ao flexible DC transmission project, China. A cross‐mapping method is designed combining the critical parameters of DCSFCL and the system parameters. A three‐terminal simulation model of the flexible DC transmission system is constructed through MATLAB/Simulink and the design process of DCSFCL parameters is introduced. A cyclic calculation approach is proposed for the design of DCSFCL parameters through three fault conditions of the power system. Meanwhile, impact current short‐circuits test and artificial ground short‐circuit test were conducted on the prototype. Test results show that the designed DCSFCL meets the requirements of practical applications. [ABSTRACT FROM AUTHOR]

Single-stage grid-interfaced PV topologies have challenges with high grid fault currents, despite being more efficient, simpler to implement, and less expensive than two-stage ones. In such systems, a single inverter is required to perform all grid-interface tasks. i.e., maximum power point tracking (MPPT), DC voltage stabilization, and grid current control. This necessitates a hardware-based fault current limitation solution rather than a software-based one to avoid adding to the inverter's control complexity and to mitigate the implications of PV system tripping. Therefore, in this study, a dual-functional non-superconducting saturated-core inductor-based (SCI) reactor is proposed to be applied at the output of a single-stage PV inverter. It involves two operation modes: a grid pre-fault mode where it filters the line current, hence minimizing its THD, and a grid-fault mode where it acts as a fault current limiter (FCL). Controlling the DC saturation current flowing into its control winding terminals alters the core magnetization of the SCI to vary its impedance between a low value during normal utility operation and a maximal value during faults. Consequently, the system is protected against inverter failures or unnecessary circuit-breaker tripping, which preserves service continuity and reduces system losses. Moreover, compared to existing FCLs, the proposed topology is an appealing candidate in terms of cost, size, reliability, and harmonic filtering ability. The bi-functionality and usefulness of the proposed reactor are confirmed using simulation and experimental results. [ABSTRACT FROM AUTHOR]

The current‐limiting reactor is currently the most used fault current limiting technique to ensure the fault ride‐through of the multi‐terminal dc grid. However, its configuration will significantly prolong the fault current clearance time and increase the dissipated energy of dc circuit breakers. Therefore, this paper proposes a cost‐effective multiline fault current limiter for multiport application in multi‐terminal dc grids, which can effectively limit the rising speed of fault current through the integrated current‐limiting reactors without time delay and significantly reduce their negative impacts on the performance of dc circuit breakers by bypassing the current‐limiting reactors through the solid‐state switch units during the fault current interruption process. The topology and operation process of the multiline fault current limiter are introduced at first. Then, the economic comparison of the proposed device with the existing solutions is presented. Finally, the feasibility and superiorities of the proposed device are verified by extensive simulations and scaled‐down experiments. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Many modern limiting methods have been developed for power systems in recent years. Resistive superconductor fault current limiter (R-SFCL), one of the modern limiting methods, has advantages such as small size and low cost. R-SFCL, which theoretically transmits energy without loss in normal operation, becomes high resistance in case of fault and reduces fault current level. However, R-SFCL, which rapidly increases its resistance during a fault, cannot immediately switch to superconductivity after the fault. During this period, which is called the recovery time, R-SFCL causes unwanted voltage drops and power losses under normal operating conditions. Therefore, recovery time is an important design parameter that should be kept short. With the bypass breaker proposed in this study, the recovery time was shortened, and voltage stability was improved. In addition, the system's reliability is increased by providing breakers' controls from two different points instead of a single point. This method is a hybrid system where limiting and protection elements are combined in one system. Modeling and simulations were performed in MATLAB/Simulink. [ABSTRACT FROM AUTHOR]

3 J. G. Bednorz, and K. A. Müller, Possible high T c superconductivity in the Ba - La - Cu - O system, Z Physik B - Condens. In late 1983, Müller, alongside his colleague J. Georg Bednorz, initiated a new project to search for superconductivity in oxides. Alex Müller (1984), from I Ferroelectrics i B 89 b , iv (1989) [[1]] With great sadness, the international ferroelectrics community mourns the loss of Professor Karl Alexander Müller, who passed away in Zurich, Switzerland, on January 9, 2023, at the age of 95. [Extracted from the article]

The doubly fed induction generator (DFIG)-based wind energy conversion system (WECS) suffers from voltage and frequency fluctuations due to the stochastic nature of wind speed as well as nonlinear loads. Moreover, the high penetration of wind energy into the power grid is a challenge for its smooth operation. Hence, symmetrical faults are most intense, inflicting the stator winding to low voltage, disturbing the low-voltage ride-through (LVRT) functionality of a DFIG. The vector control strategy with proportional–integral (PI) controllers was used to control rotor-side converter (RSC) and grid-side converter (GSC) parameters. During a symmetrical fault, however, a series grid-side converter (SGSC) with a shunt injection transformer on the stator side was used to keep the rotor current at an acceptable level in accordance with grid code requirements (GCRs). For the validation of results, the proposed scheme of PI + SGSC is compared with PI and a combination of PI with Dynamic Impedance Fault Current Limiter (DIFCL). The MATLAB simulation results demonstrate that the proposed scheme provides superior performance by providing 77.6% and 20.61% improved performance in rotor current compared to that of PI and PI + DIFCL control schemes for improving the LVRT performance of DFIG. [ABSTRACT FROM AUTHOR]

The level of fault current increases as urban power grid expands in recent years. The traditional relay protection has difficulties in preventing the increased fault current in power grid. Magneto-biased superconducting fault current limiter (SFCL) is a novel technology with two-stage fault current limiting capability of reducing the level of fault current in the first half of the cycle and further in the second cycle. It consists of a double-split reactor, a non-inductive YBCO component, and a fast circuit breaker. Achieving its coordination with relay protection can reduce the reconstruction cost of power system and contribute to the promotion of SFCL. This paper analyzes the SFCL's operating mechanism at first. Then, a typical 10 kV IEEE 9-bus power system model including the magneto-biased SFCL is built to theoretically investigate the quench and current limiting characteristics and validate the feasibility of SFCL. Finally, a distance protection setting of a simplified 10 kV urban power grid is calculated and the influence of the introduction of the magneto-biased SFCL on the distance protection is quantified. The simulation results of single-phase short-circuit fault show that the zone I and zone II of distance protection can be properly activated and there is little impact on the distance protection of zone III. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

DFIG-based wind turbine has significantly reduced the power rating, cost of the converter and enables subsynchronous and super synchronous operation but it has largely suffered in maintaining the transient stability and power balance between the generator and grid panel when grid faults has occurred. Formerly, the methods such as PID controller, fuzzy controller, PI controller could maintain the stability to the certain extent only since the nature of the wind power plant is unpredictable and also grid faults can occur at any time so this DFIG-based wind turbine is in need of predictive controller for anticipating faults in grid side. To normalize this situation, this work has proposed a (Stochastic dynamic Programming) (SDP) based Non-linear model predictive controller (NMPC) where nonlinear load would be linearized by min-max normalization algorithm and then voltage profile would be analyzed using support vector regression; consequently, based on the analyzing result, dynamic programming based on stochastic would take the action dynamically. By this way, the proposed system has been maintaining the transient stability and power balance between the generator and the grid optimally. [ABSTRACT FROM AUTHOR]

The development of industrial technology is based on electronic devices that are sensitive to power quality. Thus, the demand for high-quality and reliable power supplies is increasing. Voltage sag results in severe problems in the manufacturing process of power quality-sensitive industrial loads. When a fault occurs in a multi-ground power distribution system, the magnitudes of the fault current and voltage sag in the faulted and nonfaulted feeders become high. Hence, installing a superconducting fault current limiter (SFCL) is an effective method of compensating for fault current limitation and voltage sag. This study evaluates the effects of improving the magnitude, duration, and frequency of the voltage sag according to the type of SFCL used. First, a fault in the power distribution system is analyzed using PSCAD/EMTDC, a power system simulation software, according to the fault current-limiting element (CLE) and the type of SFCL. Second, the expected voltage sag frequency caused by a feeder fault in the power distribution system is assessed. Finally, the voltage sag improvement effect according to the CLE and the type of SFCL are compared. The trigger-type SFCL with a resistor as a CLE has been evaluated and found to be effective in improving voltage sag. [ABSTRACT FROM AUTHOR]

The field null configuration of a poloidal magnetic field is one of the critical conditions for achieving Ohmic breakdown during the initial discharge of a new tokamak. The issue of the Ohmic breakdown on the NanChang Spherical Tokamak (NCST) is still not solved satisfactorily although plasma currents of about 2 kA were found. Hence, a removable three-dimensional magnetic probe (RTMP) system consisting of 25 magnetic probes was designed, calibrated, and constructed on the NCST to evaluate the field null inside a vacuum vessel. After repeated tests, the RTMP system exhibited outstanding performance in terms of accuracy and stability with errors of about 1%. Meanwhile, the RTMP system successfully measured the toroidal field (TF) coil ripples at the magnetic axis. During experiments, the stray field arising from the TF coil implied a strong link between the flexible connection of the TF coil and the Ohmic breakdown on the NCST. After the field null was effectively modified by using a new flexible connection of the TF coil and controlling the induced current in the poloidal field coil, the NCST tokamak reproducibly obtained 20 kA plasma current with the limiter configuration during the plasma current flat-top phase. [ABSTRACT FROM AUTHOR]

Regarding HVDC systems wherein the total isolation of the failed circuit is not a practical solution, AC/DC line faults on HVDC systems using Voltage Source Converters (VSC) are a significant concern. In the HVDC system, an insulated-gate bipolar transistor (IGBT) is employed because it can take a maximum current and is also used in many industrial applications. Faults in an HVDC system's rectification or inverter portion significantly impact system reliability. In the HVDC system, many failures are examined, including an actuator, controller abnormalities, malfunctions throughout the inverter unit, overheating, and a 3-phase short circuit. Usually, the most frequent faults in an HVDC system are pole-to-earth faults on the DC-bus and 3-phase to-ground faults (A.C. faults). This article presents a terrific fault-current controller (TFCC) to limit the D.C. and A.C. fault currents for more significant improvement of the system capability. This study examines the characteristics of the VSC-HVDC with a 2-level VSC-HVDC network during cascading faults (D.C. and A.C. faults) to truly comprehend the network under these kinds of faults. The proposed technique's performance is investigated and compared with the existing techniques. Then the findings are obtained using the MATLAB tool. [ABSTRACT FROM AUTHOR]