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This study elaborates upon a new modular split‐tooth permanent magnet‐assisted switched reluctance motor (MSTPM‐SRM). In the proposed topology, the stator comprises six modular E‐cores in which the middle poles are split into two teeth. Two permanent magnets (PMs) are placed between each module's middle and side poles. Primarily, the proposed topology is introduced. Next, the principle of operation of the proposed topology are elucidated, and the magnetic equivalent circuit analysis is adopted in order to validate the operational basics. It is proved that the embedded PMs significantly increase the air‐gap's flux density and adjusts the poles' flux density. The flux density distributions, static, and steady‐state characteristics of the proposed MSTPM‐SRM motor and its PMless counterpart are extracted by utilising 2‐D finite element analysis. It is illustrated that the average torque of the proposed MSTPM‐SRM is dramatically increased compared to its PMless counterpart, especially at high excitation currents. Furthermore, the cogging torque analysis is done and it is shown that the proposed structure has approximately zero cogging torque. Finally, a prototyping version of the proposed motor is fabricated, and the experimental results are elicited. It is shown that the experimental results endorse the simulation results. [ABSTRACT FROM AUTHOR]

This paper introduces a new high step‐up multi‐input multi‐output (MIMO) DC–DC converter control‐based pole placement suitable for photovoltaic system applications. The suggested topology has a high stability current control. Low element number, high voltage conversion ratio, and low ripple input current are the main advantages of the proposed converter. The capability to use several energy resources with different voltage/current characteristics, increase the number of inputs and outputs arbitrary without duty‐cycle limitation, and control each input unit power switch independently are other advantages. The operation principle of the suggested topology, steady‐state analysis in continuous condition mode (CCM), and parameter design are analyzed. A comparison between the suggested topology and other converters is applied. Two‐input two‐output version of the suggested topology in 200 W at an operating 50 kHz switching frequency is analyzed. Finally, the Typhoon HiL‐404 emulating setup is applied to verify the performance and efficiency of the suggested high‐step‐up MIMO DC–DC power converter. [ABSTRACT FROM AUTHOR]

This work proposes a novel topology of two‐output high voltage rate DC‐DC converter based on coupled inductor and voltage multiplier cells (VMCs) techniques for renewable energy usages like photovoltaic (PV) systems. The proposed structure has two independent output ports with two voltage gains (M1 and M2). Low voltage stress across the power switch and diodes, common ground between input and output ports, high efficiency, and reduced number of elements are the advantages of the suggested converter. The used diodes are switched at zero current switching (ZCS) and zero voltage switching (ZVS) conditions, which reduce the losses of diodes and subsequently increase the power efficiency. Due to the usage of the coupled inductor, there is no need to a high value of the power switch's duty cycle. Therefore, a low conduction loss and higher efficiency can be obtained. On the other hand, because of the reduced voltage stresses, low rated semiconductors can be used for operation of the presented converter, which decrease the cost and the volume. To demonstrate the performance and effectiveness of the proposed topology, operation principles, steady‐state and efficiency analysis, and also the comparison assessment are provided. Finally, a 200 W experimental development with 50 kHz operation frequency, 20 V input voltage, and 200 and 100 V loads voltages has been implemented in the lab to prove the mathematical surveys. [ABSTRACT FROM AUTHOR]

Summary: In this study, a novel method is proposed for current control (CC) of an active power filter (APF) of the aircraft power system, which is based on a fuzzy inference system (FIS). The control system is designed according to the instantaneous power theory. Two other conventional CC methods consisting of the hysteresis current control method (HCCM) and adaptive hysteresis current control method (AHCCM) are utilized in the study and their results are compared with the proposed fuzzy current control method (PFCCM). It is shown that the proposed method is more successful in eliminating harmonics without drawbacks of conventional methods such as high and variable switching frequency which hardens system design and utilization. The study is carried out in MATLAB\Simulink environment to prove the applicability of the proposed method. [ABSTRACT FROM AUTHOR]

Summary: A single‐switch ultra‐high voltage DC‐DC converter is proposed in this paper. In the introduced structure, a voltage multiplier cell (VMC) and three‐winding coupled inductor (CL) are integrated to obtain an ultra‐large voltage gain. The input current ripple of the presented configuration is very low due to utilizing an inductor in the input part of the converter which is a very important factor in clean energy applications. The CL leakage inductance energy is successfully recovered, and the main power switch voltage stress is clamped because of using a passive clamp circuit. Therefore, a switch with low os‐state resistance can be applied, which declines the conduction losses as well as the cost of the suggested topology. Moreover, the common ground between the input and output of the proposed configuration makes it suitable for many applications such as photovoltaic systems. Some important merits include ultra‐high voltage gain, operating in low duty cycles, reduced voltage stress of semiconductors, continuous input current, and high efficiency, which make the introduced converter very suitable for clean energy applications. The operation principle, steady‐state analysis, design considerations, and theoretical efficiency analysis of the suggested converter are discussed completely in the paper. Also, the superiority of the proposed converter over recently suggested similar most important DC‐DC converters is demonstrated in the comparison study. Finally, the performance and theoretical analysis of the converter are validated with the experimental results at an output voltage of 450 V and an output power of 250 W. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study presents a novel DC reactor‐based ferroresonance and fault current limiter (DRFFCL) for stabilising ferroresonance oscillations of potential transformer (PT) in 33 kV distribution network and decreasing the amplitude of the fault current to an acceptable level. At first, the ferroresonance overvoltage is introduced and various types of overvoltage in the PT are studied. Then, the effects of the suggested DRFFCL on these oscillations are investigated. It is shown that the proposed DRFFCL not only can control the ferroresonance oscillations, but also can decrease the fault current amplitude in the case of short‐circuit faults occurrence. The DRFFCL performance is simulated using MATLAB software and a scaled‐down laboratory prototype is implemented and tested for the simulation results validation. The measured results are in agreement with the simulation results and clearly show the ability of the DRFFCL for controlling both the ferroresonance overvoltage and fault current. [ABSTRACT FROM AUTHOR]

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 presents a novel structure for DC reactor type fault current limiter (DRFCL), which can suppress the fault current in distribution networks. The proposed DRFCL is composed of a DC reactor, a bridge rectifier, and anti-paralleled IGBTs power electronic (PE) switch. The DC reactor contains main and supplementary windings. The main winding has a high inductance and acts as a DC reactor. The supplementary winding is used as a control means for fast FCL operation. The fast response allows the cost, weight and volume of the DC reactor to be reduced. The proposed DRFCL reduces the overvoltages on the devices and it has lower number of components, therefore, it can be economic. Analytical solutions, to describe the performance of the proposed DRFCL are presented and the proposed model is simulated via MATLAB software. Finally, a one-phase prototype structure is built and experimental results are studied to show the capability of the proposed DRFCL. [ABSTRACT FROM AUTHOR]

Abstract: The main goal of this paper is the determination of the effect of the metal oxide varistor (MOV) on various ferroresonance modes including fundamental resonance, subharmonic and chaos mode which are generated in electrical power systems. Chaos theory is used for analyzing this effect. Also, the bifurcation, phase plan diagram and time domain simulation are used for this purpose. The proposed power system contains a no-load or lightly loaded power transformer. The magnetization curve of the transformer core is modeled by a single-value two-term polynomial. The core loss is modeled based on the flux of the transformer. The MOV modeled as a nonlinear voltage dependent resistance. The suppression effect of MOV on chaotic ferroresonance in power transformer is studied in this paper. The simulation results confirm that connecting the MOV to the transformer has a considerable suppression effect on ferroresonance phenomena. [Copyright &y& Elsevier]

In this article, a simple case of ferroresonance in a three-phase transformer is used to study the effect of a metal oxide surge arrester on the control of chaotic ferroresonance and duration of chaotic transient in a power transformer including non-linear core losses. The time-domain simulations are derived using MATLAB (The MathWorks, Natick, Massachusetts, USA) for a three-phase 50-MVA, 635.1-kV power transformers while one of its phases is opened. The magnetization characteristic of the power transformer is modeled by a single-value two-term polynomial. The non-linear core losses are modeled by a third-order power series in terms of voltage, and the core losses non-linearities are considered as well. The simulation results show that connecting the metal oxide surge arrester to the transformer exhibits a great suppressing effect on occurred ferroresonance over-voltage. [ABSTRACT FROM PUBLISHER]

Abstract: Based on the concept of the external power system dynamic equivalent obtained for the study system, in this paper a reduced-order artificial neural network is proposed, to construct a model for the external part. The mastermind behind the proposed method is to identify the external part as a dynamic–algebraic ANN, and this separation between dynamic equations in the state space and algebraic equations is useful to solve the prediction problem. Moreover, using similarity transformations, the state space model can be simplified, such that all the nonlinearities are embedded in the algebraic part. Since usually the study system equations are available in the continuous time domain, the external part is converted to the continuous time domain by a novel method. To obtain this model, the system should be excited first by a sort of random disturbances, and then data measured on the boundary nodes is used to identify the model. Identification process is accomplished by training the proposed network which can be used to predict behavior of the external system with a high degree of accuracy. Such an equivalent has wide applications for dynamic stability studies. [Copyright &y& Elsevier]

• A brief review is given on fault current limiter placement and its function in power system. • Reviewing of the magnetic structure and magnetic equivalent circuit of inductive fault current limiter. • Analysis of the imposed inductance of inductive fault current limiters during the normal and fault condition. • Extracting main features of inductive fault current limiters based on review and classification of inductive fault current limiters. • Presenting practical comparison among inductive fault current limiters. 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. [ABSTRACT FROM AUTHOR]

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]