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42 results on '"Teguar, Madjid"'

3. Canay Inductance Impact Characterization on Dynamic Behaviour of Synchronous Machines.

Author

Leguebedj, Farid, Boukhetala, Djamel, and Teguar, Madjid

Subjects
ELECTRIC inductance, STATORS, SYNCHRONOUS generators, MACHINERY, ROTORS, VOLTAGE
Abstract

The conventional synchronous generator model accurately represents only the stator circuit. However, when considering transient effects on rotor quantities such as rotor voltage and current, accurate predictions can be achieved by properly incorporating the field and damper considerations with the stator circuits in an equivalent model. Besides, it has been observed that simulated responses obtained using the conventional model with calculated machine parameters frequently do not align well with the actual measured responses, especially for the rotor winding. This paper analyzes the effect of the d and q axis parameters of synchronous machines, focusing on accurately determining these parameters, particularly the Canay inductance. It investigates the impact of precise determination of these parameters from the time constants of the direct axis operational inductance on transient response and stability. Through simulation studies on a high order model synchronous generator system, the paper compares transient performances with and without considering Canay inductance, shedding light on its effects. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Corona Ring Improvement to Surface Electric Field Stress Mitigation of 400 kV Composite Insulator

Author

Salhi, Rabie, Mekhaldi, Abdelouahab, Teguar, Madjid, and Kherif, Omar

Abstract

This articles aims to enhance the performance of a 400 kV composite insulator by minimizing electric field stress along its surface using COMSOL Multiphysics. The study employs optimization techniques for the corona ring, initially targeting key parameters such as the ring tube radius, corona ring radius, and corona ring height. Recently used optimization algorithms for engineering applications, namely constrained optimization by linear approximation (COBYLA), coordinate search (CS), and Nelder–Mead (NM), are utilized to determine the most effective one for the optimization purpose. The results indicate that the three algorithms converge around similar values, with COBYLA exhibiting a lower iteration number. Furthermore, our research confirms that increasing the corona tube radius results in a reduction of electric field when considering the other optimized parameters; however, this leads to an increase in the corona ring weight. To resolve this concern, we conduct a reoptimization of the ring shape by targeting eight specific points that form a polynomial interface replacing the original ring. The obtained results demonstrate that the reoptimized shape effectively reduces surface electric field, although it leads to an increase in the ring weight. Nonetheless, this approach aids in identifying critical regions of surface deformation that interact with the electric field. In light of this, we explore an alternative approach that involves replacing the new shape with multiple corona rings positioned in the most deformed regions and then optimizing their positions. This approach helps to achieve better results of surface electric field and overall weight, under clean and polluted surfaces.

Published
2024
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13. Quantifying time-dependent structural and mechanical properties of UV-aged LDPE power cables insulations.

Author

HEDIR, Abdallah, SLIMANI, Ferhat, MOUDOUD, Mustapha, LAMROUS, Omar, TOUAM, Tahar, TEGUAR, Madjid, HADDAD, Abderrahmane, and DURMUS, Ali

Subjects
CHAIN scission, FOURIER transform infrared spectroscopy, ATOMIC force microscopy, LOW density polyethylene, DIELECTRIC strength
Abstract

This paper reports effects of ultraviolet (UV) light radiation on the physicochemical, electrical and mechanical properties of low-density polyethylene (LDPE) cable insulating materials. Changes in structural and morphological properties of UV-aged samples were characterized by various analytical methods such as attenuated total reflection Fourier transform infrared spectroscopy (ATRFTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Additionally, elongation at break, tensile strength, dielectric strength, and optical properties were also evaluated. Changes in some physical properties of LDPE after exposing to UV irradiation clearly highlighted that the polymer underwent the structural degradation. In addition, it was also found that such degradation yielded both crosslinking and chain scission as two competing processes during UV aging. [ABSTRACT FROM AUTHOR]

Published
2022
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40. On the performance of a 21-level asymmetrical multilevel voltage inverter

Author

Kherif, Omar, Zebbadji, Tahar, Chiheb, Sofiane, Benmahamed, Youcef, Teguar, Madjid, Kherif, Omar, Zebbadji, Tahar, Chiheb, Sofiane, Benmahamed, Youcef, and Teguar, Madjid

Abstract

This paper deals with a 21-level asymmetrical voltage inverter with a reduced number of switching components and isolated DC sources. A brief description of the used multilevel inverter is provided, including the circuit configuration and control signals. A pre-calculated switching technique is implemented where the inverter performance is achieved throughout a parametric analysis (THD and fundamental component amplitude). Therewith, selected simulation results are shown to discuss the output voltage and current for different RL-loads and modulation index. The computed current and load voltage signals show a reduced THD that is varying in the permissible limits.

41. Cap-pin glass insulator simulation and leakage current waveform extraction

Author

Salhi, Rabie, Mekhaldi, Abdelouahab, Teguar, Madjid, Kherif, Omar, El Amine Slama, Mohamed, Salhi, Rabie, Mekhaldi, Abdelouahab, Teguar, Madjid, Kherif, Omar, and El Amine Slama, Mohamed

Abstract

This paper presents a simulation of a HV glass insulator and a methodology to extract leakage current signal. Using 3D profiles, COMSOL-based simulations are conducted at a 50 Hz voltage waveform of different magnitudes. The 1512L cap and pin glass insulator is employed since it is widely used in Algerian desert regions. Potential and electric field distributions, along with the temperature rising, are presented and discussed. The current density is extracted and used to compute the leakage current signal. The obtained results are presented and discussed.

42. Optimizing corona ring design for 400 kV cap-pin string insulator to minimize surface electric field under various surface conditions

Author

Salhi, Rabie, Mekhaldi, Abdelouahab, Teguar, Madjid, Kherif, Omar, Salhi, Rabie, Mekhaldi, Abdelouahab, Teguar, Madjid, and Kherif, Omar

Abstract

The objective of this paper is to reduce the electric field stress along the surface of the 400 kV cap-pin string insulator by optimizing its corona ring design. The cap-pin string insulator, composed of glass material and consisting of 1512 L units, is designed and investigated within a 2D-axisymmetric environment using COMSOL software. Firstly, we optimize the corona ring’s radius, tube radius, and height. Secondly, the corona ring shape is optimized to more effectively decrease the surface electric field, despite the resulting increase in its weight. Finally, the optimized shape is replaced by multiple corona rings, each with a small radius, positioned in the most deformed area, to enhance the insulator’s performance in terms of both surface electric field and corona ring weight. The COBYLA algorithm is utilized as the optimization method throughout the study. This research examines clean, uniformly polluted, and Room Temperature Vulcanizing (RTV) silicon rubber-coated surface conditions. The obtained results are presented and discussed.

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