This article presents a novel high-temperature superconductive (HTS) power flow controller and current limiter (PFCCL), which limits fault currents and manages power flow in the intended transmission line. The proposed device includes series HTS reactors, HTS controlling dc coil, recovery resistive coil, and power electronic switches, which protects the microgrid from the upstream ac grid, short-circuit faults, and it controls the power flow between a microgrid and the upstream grid. Performance of the proposed PFCCL is mathematically analyzed, utilizing MATLAB and Maxwell software, and then validated by laboratory scaled-down experimental setup. It is shown that the simulation results are in fair agreement with the developed experimental laboratory setup results.

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The protection of distribution networks is one of the most substantial issues, which needs special attention. Using appropriate protective equipment enhances the safety of the power distribution network during the fault conditions. Fault current limiter (FCL) is a kind of modern preserving system being used for protecting power networks and equipment. One of the main concerns of power networks is the voltage restoration of buses during faulty conditions. In this study, a group of coordinated DC reactor type faults current limiters are designed and tested to protect the network and restore its buses voltage within the fault period. To coordinate FCLs and measurement devices during the fault sequences, a wireless communication system and decision-making computer are used. The proposed FCLs coordination strategy is modelled and simulated in MATLAB platform and the results are validated by the developed laboratory test setup.

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Power systems are subjected to various types of faults as well as ferroresonance overvoltages. These results in the interruption of the normal operation of the power grid, failure of equipment, electrical fires, etc. To tackle these issues, this study proposes a dual function limiter to control the fault current and ferroresonance phenomenon in power systems. This compound device is a solid-state series transformer-based limiter that includes IGBT switches, capacitors, rectifiers, and a DC reactor. During the grid normal operation, the proposed limiter is not active and therefore is invisible and it operates in the instant of fault inception or ferroresonance overvoltage occurrences. Analytical studies in all operation modes are presented and assessments on the performance of the proposed ferroresonance and fault current limiter (FFCL) are conducted in Matlab. Simulation results confirm the reported analytical studies and FFCL's performance.

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Ferroresonance occurrence is a source of damage, causing overvoltage on voltage transformer (VT) and isolators of the grid equipment. Some solutions are available to protect VTs from the ferroresonance overvoltage. However, they just act after the ferroresonance occurrence. In this letter, to prevent the occurrence of ferroresonance, a dc reactor-based protection device is introduced. Analytical studies and simulations by MATLAB/Simulink and Maxwell ANSYS demonstrate the capability of the proposed protection device as a VT ferroresonance inhibitor. Experimental results from a scaled-down laboratory prototype are also provided to verify the proposed solution.

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A fault current limiter (FCL) is an effective means of limiting fault currents that is a promising power system protection solution. This paper presents a comparative survey of research activities and emerging technologies of FCL and discusses in detail the features of an inductive FCL. Inductive FCLs possess superior performance and higher speed of operation in comparison with other FCLs. The magnetic structure of an inductive FCL is instrumental to superior performance. The review study discusses the feasibility and effectiveness of the magnetic flux based FCLs. In addition, the magnetic behavior of FCLs is discussed considering the analytical study of their equivalent circuits. Moreover, a comprehensive comparative study of inductive FCLs is presented based on their technical operational characteristics.

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The main propose of this paper is to protect medium voltage smart grid applications from damages of the destructive fault current based on resonant type fault current limiter. Because of the series connection of a capacitor and a reactor, the Series Resonance Fault Current Limiter (SRFCL) is invisible during normal operation and shows negligible impedance in the line. During the fault, a control circuit connects a rectifier bridge to the series reactor and induces a DC voltage on it. In this instant, the series reactor is short circuited, and the series capacitor remains in the line. Thus, the impedance of the series capacitor reduces the amplitude of the fault current.

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Expansion of high-voltage dc (HVdc) systems to multi-terminal HVdc (MT-HVdc) systems/grids considerably increases the short-circuit levels. In order to protect the emerging MT-HVdc systems/grids against fault currents, proper dc fault current limiters (FCLs) must be developed. This paper proposes an innovative high inductance solid-state dc-reactor-based FCL (HISS-DCRFCL) to be used in HVdc applications. In fact, during the HISS-DCRFCL normal operation, its inductance value is extremely low, and its value becomes considerably high during the fault period, which decreases the fault current amplitude. The proposed HISS-DCRFCL performance is analyzed by MATLAB/Simulink and the simulation results are verified and confirmed by laboratory experimental results using a scaled-down laboratory prototype setup.

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The protection of sensitive loads against voltage drop is a concern for the power system. A fast fault current limiter and circuit breaker can be a solution for rapid voltage recovery of sensitive loads. This paper proposes a compound type of current limiter and circuit breaker (CLCB) which can limit fault current and fast break to adjust voltage sags at the protected buses. In addition, it can act as a circuit breaker to open the faulty line. The proposed CLCB is based on a series L-C resonance, which contains a resonant transformer and a series capacitor bank. Moreover, the CLCB includes two anti-parallel power electronic switches (a diode and an IGBT) connected in series with bus couplers. In order to perform an analysis of CLCB performance, the proposed structure was simulated using MATLAB. In addition, an experimental prototype was built, tested, and the experimental results were reported. Comparisons show that experimental results were in fair agreement with the simulation results and confirm CLCB’s ability to act as a fault current limiter and a circuit breaker.

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This paper proposes a novel bridge-type solid-state fault current limiter (BSSFCL) based on one series reactor which operates in ac and dc modes. The proposed BSSFCL includes a rectifier bridge with a reactor. This reactor is used as a dc reactor in normal operation mode and as an ac reactor in fault conditions. The advantages of the proposed BSSFCL over the existing dc reactor-type FCLs are its negligible impedance in normal operation mode and its high impedance during a fault interval using simple and novel switching. In other words, during the normal operation mode, the proposed BSSFCL operates in dc mode and in the fault interval, its topology is changed to the ac mode. This switching decreases the switching transient recovery voltage and introduces considerable impedance during the fault period. MATLAB/Simulink software is used for simulations and a prototype is designed and tested for results verification, and to show the performance of the proposed BSSFCL.

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This paper proposes a novel Fault Current Limiter (FCL) for the application on power systems to control voltage sags at the Point of Common Coupling (PCC) during faults. This new FCL is a resonance transformer, whose primary side is connected to a series capacitor and transmission line. Also, the secondary side of the transformer is switched by a semiconductor device to change the impedance of the primary side of the transformer. The main control component is a fast-closing switch connected in parallel with the secondary side of the transformer, which is driven by the power electronic switch. It can respond within 1 msec. When a fault occurs, the switch closes and bypasses the transformer secondary side and fault current is limited by the reactor. So, by increasing the existing resonant frequency, the fault current is limited. The simulated and experimental results show that it is feasible to develop the FCL with low cost and high reliability. The experimental results show the capability of the proposed FCL, too.@en

This paper studies effect of power electronic load and its current harmonics in increasing current of shunt capacitance in the distribution network. Analytical method is done to show the effect of power electronic load on the current harmonic In order to show the proposed method effectiveness, a simple power electronic load is used including a rectifier bridge, a smoothing capacitor filter and a resistance. It has been shown that by increasing power electronic load, the shunt capacitance current is increased where the rate of current variation is related to the structure of power electronic load. MATLAB and PSCAD software's are used to simulate the proposed distribution network.

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In this paper, a novel solid-state fault current-limiting circuit breaker (SSFCLCB) based on a series resonance LC tank is proposed. Since the series configuration of the resonance structure (a capacitor and a reactor) of the SSFCLCB is invisible during normal operation mode, it shows negligible impedance in the line. In fault conditions, the SSFCLCB topology changes to a rectifier bridge and feeds the resonance structure with rectified ac voltage. With the rectified voltage, the series capacitor is charged and, as a result, the faulty line is opened and the fault current is seized. Hence, the suggested SSFCLCB cannot only limit the fault current but can also open the faulty line and acts as a circuit breaker. For confirmation of these aspects, simulations are performed using MATLAB software. Also, a prototype structure is designed and built for results confirmation. This experimental setup is established to prove that SSFCLCB has excellent performance in its startup, normal operation, and current-limiting/breaking conditions. The results show that the SSFCLCB has the ability to improve distribution network reliability and it can decrease the network fault current level successfully.

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In this paper, voltage sag and voltage Total Harmonic Distortion (THD) in the distribution network are studied. The proposed electrical network is modeled by electrical source, Line and source impedances. It is assumed that the electrical load of this network is a sample electronic load. This load is a rectifier bridge where its output terminal is connected to a capacitor bank and a linear resistance. The distribution network power quality is analyzed by changing the load impedance, the capacitor bank and number of load in the network. The Voltage sag and THD in the distribution network are studied using PSCAD and MATLAB software.

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