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Multifunctional Distributed MPPT Controller for 3P4W Grid-Connected PV systems in Distribution Network with Unbalanced Loads زياد محمد محمد محمد
The integration of photovoltaic (PV) systems with three-phase four-wire (3P4W) distribution networks has imposed several challenges related to existing unbalanced loads, reactive power generation and harmonics content. In this paper, a multifunctional distributed maximum power point (MPPT) controller for grid integration of PV systems is proposed. The proposed distributed MPPT controller is developed based on employing a four-leg three-level T-type multilevel inverter. The proposed inverter performs multifunctionalities, including distributed MPPT, neutral current compensation for the unbalanced loads, supplying reactive power into the grid and the grid integration. Moreover, the proposed inverter overcomes the stochastic behavior of both the PV generation with partial shading problems and its operation with unbalanced loads as well. Furthermore, the new proposed controller injects sinusoidal output currents with decreased levels of total harmonic distortion (THD) into the grid. The tested case study is investigated for the various operating scenarios of PV generation and load demands. The results and tabulated performance comparisons have proven the superior performance of the proposed multifunctional PV generation system. The results show the ability of the proposed controller to efficiently extract distributed MPPT for all PV modules at all the tested scenarios. Additional improvement of the energy efficiency is achieved through the elimination of the neutral current due to existing unbalanced loads. ...
Enhancing the performance of directional relay using a positive-sequence superimposed component زياد محمد محمد محمد
In this article, we propose a fault directional identification scheme that depends on the positive-sequence components of current based on an investigation of pre-fault and fault phase angles. The proposed protection scheme is developed for both distribution and transmission systems. However, as the current-only approach depends on the pre-fault current direction as the polarizing quantity, if the pre-fault current direction changes during normal conditions, the direction definitions would be swapped. This will cause a problem for the current-only approach. Therefore, a signal processing-based solution is presented, leveraging the fact that a change in direction in the pre-fault condition is associated with a phase angle change of 180°. The proposed protection scheme is examined with two different power system configurations (distribution and transmission systems). Simulation experiments conducted using ATP/EMTP software verified the feasibility of the proposed protection scheme. Moreover, the validity of the proposed protection scheme is compared with that of other directional schemes. The results confirmed the accurate operation of the proposed scheme. ...
PUBLICATIONS : Conference medien zeghid

Performance Evaluation and Design Considerations of Lightweight Block Cipher for Low-Cost Embedded Devices

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RESEARCH INTEREST medien zeghid

Cryptography, Architectural Synthesis for the Crypto-systems, System Modeling, Synthesis of communications for the SOC, Image & Video Coding, Adequacy Algorithm Architecture, High-level synthesis.

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FPGA Implementation of Multi-User Detection Genetic Algorithm Tool for SDMA-OFDM Systems Mohammed Ahmed Alansi

Robust multi-user detection (MUD) methods based on space division multiple access (SDMA) techniques are essential to efficiently exploit the electromagnetic spectrum. In this paper, an adaptive Genetic Algorithm-based tool for SDMA-OFDM Systems (GASOS) is developed to improve the performance and computational complexity in cases of fully-loaded and overloaded multi-user scenarios. The data flow in GASOS is appropriate in pipelining and parallelization to reduce operational time. A new GASOS-based MUD hardware design for SDMA-OFDM systems is proposed using FPGA architecture.

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MC-OFDMA for multi-user detection schemes in powerline communication Mohammed Ahmed Alansi

Support of multiple users in wideband powerline communication (PLC) is essential to enhance the dependence on such emerging systems. This paper presents novel adaptations of the space division multiple access (SDMA) techniques to PLC. Multicarrier data transmission and orthogonal frequency division multiple access (OFDMA) techniques are invoked to mitigate the technical challenges of PLC channel impairments and enhance the spectral e±ciency. Performance is enhanced using orthogonal Walsh–Hadamard codes. Linear and nonlinear multi-user detection (MUD) schemes are investigated, including the optimal maximum likelihood (ML) methods and the near-optimal sphere detectors(SDs). Presented results indicate the potential of the proposed scheme to enhance wideband PLC systems.

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Multi-User Detection for Radar and Communication Multifunction System Mohammed Ahmed Alansi

A multifunctional system that performs synthetic aperture radar (SAR) and communication tasks is presented. The system depends on orthogonal frequency division multiplexing (OFDM) waveform shaping and multiple input multiple output (MIMO) configuration to achieve enhancement in the spectral efficiency of communication operation and provide interference rejection in SAR imaging. The SAR interval idle time is utilized to enhance the communication signal through diversity. Adaptive system features are introduced to achieve multi-user detection and improve the communication reliability, by means of space division multiple access (SDMA) and space-time block coding (STBC). Investigations of linear and nonlinear multi-user detection (MUD) techniques are provided. Moreover, a genetic algorithm-based system is developed to optimize the MUD problem and to provide near-optimal performance even for overloaded scenarios. A gain of more than 4 dB is achieved at bit error rate of 10(-2).

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