Wyniki 1-4 spośród 4 dla zapytania: authorDesc:"Abdelber BENDAOUD"

Common mode conducted electromagnetic interference in inverter fed-AC motor

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The increase of switching speed and frequency in power electronics converters has greatly improved their performances and characteristics. These advantages are accompanied with the increased level of interference, so that EMI consideration is a major task for circuit designers nowadays. In Adjustable Speed Drives (ASD), the (dv/dt) leading to conducted emissions at high frequencies which are propagated both through Common Mode (CM) and Differential Mode (DM) in the system. The circulation of high frequency parasitic currents causes several unexpected problems, such as premature deterioration of motor winding insulation and ball bearings. In this paper an inverter-fed AC motor drive is analyzed in order to predict the path of conducted emissions into Common Mode (CM) configuration, showing that both propagation modes may interfere. The equivalent circuit allows frequency-domain analysis to be performed with standard circuit simulators. The proposed circuit model allows the prediction of the main common-mode HF current components. Abstract. Zwiększanie szybkości przełączania i częstotliwości w przekształtnikach energoelektronicznych pozwala na znaczącą poprawę ich parametrów. Tym korzyściom towarzyszy zwiększony poziom zakłóceń. W napędach o regulowanej szybkości ASD sygnał dv/dt powoduje zwiększoną emisję zakłóceń wysokoczęstotliwościowych w obu - w niesymetrycznych i różnicowych systemach. Obieg prądów pasożytniczych powoduje wiele nieoczekiwanych problemów, takich jak uszkodzenia izolacji uzwojeń i łożysk. W artykule przedstawiono analizę silnika zasilanego za pośrednictwem przekształtnika w celu oceny e misji zakłóceń w trybie niesymetrycznym. Schemat zastępczy pozwala na analizę w dziedzinie częstotliwości. Proponowany model pozwala na symulację i przewidywanie składowych prądów wysokoczęstotliwościowych. (Zakłócenia elektromagnetyczne w silniku AC zasilanym za pośrednictwem przekształtnika) Keywords: EMI, EMC, Common Mode, high frequency[...]

Calculation of induced current in the objects placed in the vicinity of the high voltage transmission lines

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This paper gives a method of equivalent charge for calculate and represent the electric field around the three-phase lines and the current which will be induced in the objects near the high voltage transmission lines. In this present work, we establish a calculation program based on MATLAB in order to calculate and trace the induced current by the electric field under the lines. We can make simulation for several cases in order to establish some criteria which must be studied to evaluate safety and to make the provisions necessary to minimize the influence of electric field on the human body. Abstract. W artykule zaprezentowano metodę obliczeń pola elektrycznego w pobliżu linii trójfazowej oraz prądów indukowanych w obiektach w pobliżu linii przesyłowych wysokiego napięcia. W pracy wykorzystano oprogramowanie Matlab do obliczeń pola elektrycznego pod linią. Przeprowadzono symulację dla kilku typowych przypadków w celu ustalenia kryteriów umożliwiających ochronę człowieka przed generowanym polem elektrycznym. (Obliczenia prądów indukowanych w obiektach umieszczonych w pobliżu linii przesyłowej wysokiego napięcia). Keywords: Equivalent charge, Induced current, electric field, transmission lines, simulation. Słowa kluczowe: prądy indukowane, linie przesyłowe, pole elektryczne. Introduction For the design of High voltage lines, it is necessary to dimension these installations according to the high electric fields. The electric field at the industrial frequency is a phenomenon which exists around the electric power lines. It is increasingly high used which results in taking the consequences of this phenomenon in consideration. This subject proposes to the owner of these lines the replies to the problems raised by this constraint. It’s necessary to know the determination of electric fields, their calculation and their measurement, as well as the determination of the induced currents in the objects, including in living organisms by el[...]

Dynamic Economic Dispatch Solution with Practical Constraints Using a Recurrent neural network

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This paper proposes a solution to the dynamic economic dispatch (DED) with practical constraints using a Hopfield neural network (HNN). The constrained DED which will be solved in this paper must satisfy (i) the system load demand (ii) the spinning reserve capacity (iii) ramp rate limits and (iv) prohibited operating zone. The feasibility of the proposed HNN method is demonstrated using two power systems, and it is compared with the other methods in terms of solution quality and computation efficiency. Streszczenie. Artykuł proponuje rozwiązanie dynamicznej gospodarki przesyłem energii z uwzględnieniem ograniczeń przy wykorzystaniu sieci neuronowych Hopfield (HNN). Zaproponowana metoda została sprawdzona w dwóch systemach elektroenergetycznych i porównana z innymi metodami pod względem jakości i efektywności rozwiązań obliczeniowych. (Dynamiczne rozwiązanie gospodarki przesyłem energii przy wykorzystaniu sieci neuronowych) Keywords: dynamic economic dispatch, Hopfield Neural Network, prohibited operating zone, ramping rate limits. Słowa kluczowe: sieci neronowe Hoipfielda, gospodarka przesyłem energii. Introduction DED is used to determine the optimal schedule of generating outputs on-line so as to meet the load demand at the minimum operating cost under various system and operating constraints over the entire dispatch periods. DED is an extension of the conventional economic dispatch (ED) problem that takes into consideration the limits on the ramp rate of generating units to maintain the life of generation equipment [1, 2]. In general, the DED is solved by discretization of the entire dispatch period into a number of small time periods. Therefore, the static ED in each dispatch period is solved subject to the power balance constraints and generator operating limits. Previous efforts on solving static ED problems have employed various mathematical programming methods and optimization techniques ( lambda-iteration method, the base [...]

Solution of Inverse Problems in Electromagnetic NDT Using Neural Networks

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This paper presents a technique for solving inverse problems in electromagnetic nondestructive testing (NDT), using neural networks (NN). They are trained to approximate the mapping from the signal to the defect space. A crucial problem is signal inversion, wherein the defects profiles must be recovered from calculated signals by using finite element method (FEM), this method give good results by using the refinement mesh but in very long time. The idea of this paper is the exploitation of the FEM but with a middle mesh where the results are approached in short time. This signal was exploited in the inversion problem, where the maps represent the defects in the plate. The inversion results obtained with the NN are presented. The presented approach has permitted to realize good maps in a very reasonable training time with respect to others approaches. Streszczenie. Przedstawiono metodę rozwiązania odwrotnego z wykorzystaniem sieci neuronowych stosowanego w defektoskopii. Sieć jest trenowana na podstawie próbek z defektami. Pozwala to na stosowanie metody FEM ze znacznie mniejszą liczbą oczek. (Rozwiązanie problemu odwrotnego w defektoskopii elektromagnetycznej przy wykorzystaniu sieci neuronowych) Keywords: Eddy current, Finite element method, Defect characterization, Neural networks, Inverse problems. Słowa kluczowe: metoda prądów wirowych, defektoskopia, sieci neuronowe. Introduction In recent years the artificial neural network was to use in the nondestructive testing (NDT) where it’s interviewee to inverse problem. But, the NDT requires the use of the numerical analysis methods, among these methods, the finite element method (FEM). It appears to be very powerful because of its large flexibility which allows taking into consideration complex configurations [1]. Their application is widely used to detect cracks in metallic structures by using the Eddy currents [2]. This paper describes the inversion problem by using the neural[...]

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