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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. [ABSTRACT FROM AUTHOR]

This paper proposes a smart dual function series resonance ferroresonance overvoltage and fault current limiter (SRFFCL) for distribution networks. The studied network has potential transformers (PTs) with a typically low thermal capacity and high accuracy. The PT core losses are assumed to be constant during ferroresonance oscillation. The MATLAB software is used for simulation of the novel SRFFCL in distribution network, to study the PT ferroresonance overvoltage and fault current. Also, experimental results are obtained using a laboratory prototype. Both the simulation and experimental results, which are in good agreement with each other, show that the suggested SRFFCL can not only control the fault current but also adequately decrease the ferroresonance oscillation of the PT. [ABSTRACT FROM AUTHOR]

In some aircraft with traditional distribution electrical systems, the sources, distribution, and electrical loads are fully coupled. The control surfaces in traditional aircraft are based on cables and hydraulic actuators. Furthermore, the system stability mainly related to the hydraulic system and a small portion of it is related to the electrical system reliability. However, for aircraft like A380 and B787, the flight system is based on fly by wire (FBW) technology and more electric aircraft (MEA) have drawn the attention of aircraft designers. In addition, more hydraulic actuators change to the electrical actuator, which leads to more electrical generation usage. The availability of electrical energy to the loads is only ensured through overdesign, system reconfiguration, and protection. Power electronic converters are starting to be used to fully decouple the dynamics between sources, distribution systems, and loads. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

This paper studies a novel transformer-based solid state fault current limiter (TBSSFCL) for radial distribution network applications. The proposed TBSSFCL is capable of controlling the magnitude of fault current. In order to control the fault current, primary winding of an isolating transformer is connected in series with the line and the secondary side is connected to a reactor, paralleled with a bypass switch which is made of anti-parallel insulated gate bipolar transistors. By controlling the magnitude of ac reactor current, the fault current is reduced and voltage of the point of common coupling is kept at an acceptable level. Also, by this TBSSFCL, switching overvoltage is reduced significantly. The proposed TBSSFCL can improve the power quality factors and also, due to its simple structure, the cost is relatively low. Laboratory results are also presented to verify the simulation and theoretical studies. It is shown that this TBSSFCL can limit the fault current with negligible delay, smooth the fault current waveform, and improve the power quality. [ABSTRACT FROM PUBLISHER]