Amr Elnady
University of Sharjah, Electrical and electronic engineering, Faculty Member
The master-slave control is an important scheme to control the microgrid in both islanded and grid-connected modes. It has been proved that it is competitive to the droop control schemes. This presented paper shows two techniques to... more
The master-slave control is an important scheme to control the microgrid in both islanded and grid-connected modes. It has been proved that it is competitive to the droop control schemes. This presented paper shows two techniques to control the current/power of the slave inverters to precisely adjust the injected output power of the slave inverters. The adopted microgrid contains two multilevel (five-level diode-clamped) inverters. One inverter is operated as a slave inverter and the remaining inverter is operated as a master inverter. The slave inverter can be operated using two techniques. The slave inverter is operated in a direct current control (DCC) mode using nested multiband hysteresis current control. While the second technique is the indirect current control (ICC) mode through the cascaded structure of power and current loops. Simulation results show a comparative analysis, which affirms that the DCC gives much better performance for current/power control, while the ICC gives a slightly better performance for voltage stabilization at loads.
Research Interests:
This paper presents an accurate tool for tracking the voltage unbalance in the microgrid. This accurate tracking depends on a new formulation of the adaptive linear neuron (ADALINE). This formulation has accurate estimation/extraction of... more
This paper presents an accurate tool for tracking the voltage unbalance in the microgrid. This accurate tracking depends on a new formulation of the adaptive linear neuron (ADALINE). This formulation has accurate estimation/extraction of positive-, negative-, and zero-sequence voltages. The paper introduces a control scheme that stabilizes the voltages at the loads side by adjusting the positive voltage around 1 pu and mitigating the negativesequence voltage. This voltage stabilization is done through the developed control scheme, which has a cascadedloop structure for voltage and current control. The control scheme along with the suggested estimation tool gives accurate results for stabilizing the voltage at the loads side for different loading conditions.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
The master-slave control/operational scheme proves to be very efficient for operating any microgrid in different modes: Islanded and grid-connected modes. The master-slave schemes prove to be competitive compared to the droop control... more
The master-slave control/operational scheme proves to be very efficient for operating any microgrid in different modes: Islanded and grid-connected modes. The master-slave schemes prove to be competitive compared to the droop control schemes because of their admirable characteristics for the control/operation of AC microgrids. This presented paper employs the master-slave scheme as a control scheme for the operation of the microgrid. The adopted microgrid contains three multilevel (five-level diode-clamped) inverters. Two of them are operated as slave units, and the remaining unit is employed as a master unit. The slave units are operated in a current-controlled mode using developed multiband hysteresis current control. At the same time, the master inverter is operated in a voltage-controlled mode, which is responsible for maintaining both frequency and voltage at a certain level. In addition, the redundancy of the slave units is checked in case one slave unit is disconnected. The simulation results prove that master control and hysteresis current control perform well at different operating conditions.
Research Interests:
This paper presents an improved Voltage Oriented Control (VOC) scheme to control a three-phase grid-connected 7-level diode clamped inverter, where this inverter is the Distributed Generation (DG) unit that is the core of the Distributed... more
This paper presents an improved Voltage Oriented Control (VOC) scheme to control a three-phase grid-connected 7-level diode clamped inverter, where this inverter is the Distributed Generation (DG) unit that is the core of the Distributed Generation System (DGS). An optimization method is used to recursively tune the parameters of the PID controller in the presented control scheme so as to achieve the optimal performance for the DG unit in a grid-connected mode. Simulation results are carried out to show the meritorious performance of the proposed control scheme while tracking the power references, which represent the required power to be injected by the DG unit to the distribution system.
Research Interests:
Research Interests:
This paper presents an improved Direct Power Control (DPC) scheme applied to the multilevel inverter that forms a Distributed Generation Unit (DGU). This paper demonstrates the performance of active and reactive power injected by the DGU... more
This paper presents an improved Direct Power Control (DPC) scheme applied to the multilevel inverter that forms a Distributed Generation Unit (DGU). This paper demonstrates the performance of active and reactive power injected by the DGU to the smart grid. The DPC is traditionally operated by the hysteresis controller with the Space Vector Modulation (SVM) which is applied on the 2-level inverters or 3-level inverters. In this paper, the DPC is operated by the PI controller with the Phase-Disposition Pulse Width Modulation (PD-PWM) applied to the 5-level diode clamped inverter. The new combination of the DPC, PI controller, PD-PWM and multilevel inverter proves that its performance is much better than the conventional hysteresis-SVM based DPC. Simulations results have been presented to validate the performance of the suggested control scheme in the grid-connected mode.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT This paper exhibits new recursive implementation of the root-MUSIC algorithm in power system applications in order to extract the instantaneous power disturbances, which emanate from the arc furnace. The MUSIC algorithm is... more
ABSTRACT This paper exhibits new recursive implementation of the root-MUSIC algorithm in power system applications in order to extract the instantaneous power disturbances, which emanate from the arc furnace. The MUSIC algorithm is selected because it has an outstanding capability to estimate and track the frequencies of all types of distortion such as harmonics and interharmonics. The utilized algorithm has been newly developed so as to recursively track the instantaneous disturbances in the arc furnace current and consequently mitigate them. The suggested development of the recursive root-MUSIC is compared with the ESPRIT in order to prove that the adopted technique outperforms the high-resolution common techniques in a noisy or non-noisy environment. The instantaneous disturbance is formed by an innovative formulation of the recursive notch filter. Moreover, the experimental results are given to prove the practicality of the proposed concepts and techniques.
Research Interests:
This paper introduces an efficient formulation of synergetic control that is based on an integral macro-variable function. This suggested integral synergetic control is integrated with the direct power control scheme to precisely adjust... more
This paper introduces an efficient formulation of synergetic control that is based on an integral macro-variable function. This suggested integral synergetic control is integrated with the direct power control scheme to precisely adjust the injected power of the distributed generation units to the main power grid. To prove the advantageous performance of the suggested control scheme, the propounded control scheme is compared to the adaptive sliding mode control and PI controller based control scheme. The practicality of the suggested synergetic control is validated by some experimental results using rapid control prototyping through the dSpace SCALEXIO platform.
Research Interests:
Research Interests:
Research Interests:
This paper deals with controlling DC motor speed and/or torque through the multilevel Chopper circuit. The proposed switching circuit consists of four cascaded switching elements with three clamping diodes and four equal or different... more
This paper deals with controlling DC motor speed and/or torque through the multilevel Chopper circuit. The proposed switching circuit consists of four cascaded switching elements with three clamping diodes and four equal or different voltage sources connected in series. The configuration provides a constant five levels of voltage and has the ability to generate and track any reference input voltage within the source voltage range. The generated voltage has relatively very small harmonic and ripples compared to the traditional step down chopper. The profile of the generated voltage positively affects the performance of the motor armature current, the generated dynamic torque and the rotor. The simulation results show adequate voltage reference tracking, smooth speed response and reduced current and torque ripples, which normally reflect in smaller mechanical vibration and acoustic noise.
Research Interests:
This paper presents a robust control algorithm for voltage disturbance extraction and mitigation. The proposed mitigating device is the dynamic voltage restorer (DVR). The proposed DVR can compensate the voltage unbalance and mitigate... more
This paper presents a robust control algorithm for voltage disturbance extraction and mitigation. The proposed mitigating device is the dynamic voltage restorer (DVR). The proposed DVR can compensate the voltage unbalance and mitigate voltage harmonics in the time of normal operation in addition to its basic functions for mitigating different voltage sags. The suggested control algorithm employs the adaptive perceptron
Research Interests:
This paper presents an efficient utilization of Kalman filter for estimating the disturbance signal of the voltage flicker. The proposed method is able to extract the instantaneous flicker disturbance using a single extended Kalman... more
This paper presents an efficient utilization of Kalman filter for estimating the disturbance signal of the voltage flicker. The proposed method is able to extract the instantaneous flicker disturbance using a single extended Kalman filter. In this paper, the disturbance signal is modeled in a complex form to facilitate the performance of the estimation and tacking for the Instantaneous Flicker Level (IFL) of the voltage flicker compared to the conventional models that require two versions of the Kalman filter to do the same extraction process. The estimated disturbance is employed for mitigating the cyclic voltage flicker using the Unified Power Quality Conditioner (UPQC), which restores the voltage level at the load terminal to its nominal accepted value. Simulation results using MATLAB/Simulink are provided to prove the validity of the proposed method.
Research Interests:
This paper presents an innovative control scheme for the operation of parallel three multilevel diode clamped inverters to supply some loads in a microgrid. The distributed energy resources are the PV panels connected to batteries at the... more
This paper presents an innovative control scheme for the operation of parallel three multilevel diode clamped inverters to supply some loads in a microgrid. The distributed energy resources are the PV panels connected to batteries at the DC side of these inverters. The presented control scheme depends on PI controllers, which operate two cascaded control loops to stabilize the voltages and frequency at the load side. The adopted scheme coordinates the operation of the parallel inverters such that the instantaneous loads’ currents are equally shared among the inverters. Also, the presented scheme accommodates the modular structure of parallel inverters and it is robust in the case any one of the parallel inverters is disconnected/reconnected. The performance of the proposed scheme is validated using simulation results.
Research Interests:
Voltage sag is the most severe power quality (PQ) problem while current harmonics are the most common PQ problem. In this paper, a unified power quality conditioner (UPQC) mechanism is presented that mitigates these power quality... more
Voltage sag is the most severe power quality (PQ) problem while current harmonics are the most common PQ problem. In this paper, a unified power quality conditioner (UPQC) mechanism is presented that mitigates these power quality problems. This UPQC is the custom power device for mitigating the PQ problems. It combines both a series part that mitigates voltage related PQ problems and a shunt part that mitigates current related PQ problems. An improved extraction technique is introduced to extract voltage and current disturbances to help operate the UPQC that mitigates these disturbances simultaneously to enhance the PQ in the distribution system. Simulation results using MATLAB/Simulink are provided to illustrate the meritorious performance of the presented extraction technique.
Research Interests:
Received Dec 18, 2020 Revised Feb 4, 2021 Accepted Mar 10, 2021 In this paper, a non-isolated multi-level DC-DC (MLDC-DC) smooth buck converter with the LC filter is designed and analyzed. The presented topology can be used in low or... more
Received Dec 18, 2020 Revised Feb 4, 2021 Accepted Mar 10, 2021 In this paper, a non-isolated multi-level DC-DC (MLDC-DC) smooth buck converter with the LC filter is designed and analyzed. The presented topology can be used in low or medium voltage levels in several applications that use DC storage elements. The use of the proposed multilevel converter topology reduces the voltage stress across the power converter switching elements and facilitates the voltage rating of the switches. The designed LC filter for the multilevel converter is characterized by a small inductor size, which reduces the traditional bulky inductor used in the output of the traditional DC-DC converter. The reduction in the filter size is proportional to the number of the connected voltage sources, it works effectively to reduce ripple in the load currents, and it increases the voltage gain. The intensive analysis of the converter system and the experimental results show a stable operation of the proposed conve...
Research Interests:
Research Interests:
This paper presents an innovative control scheme for the multilevel inverter that is connected to the power grid as a Distributed Generation unit, DG. The paper demonstrates novel application for the voltage orientation control, also... more
This paper presents an innovative control scheme for the multilevel inverter that is connected to the power grid as a Distributed Generation unit, DG. The paper demonstrates novel application for the voltage orientation control, also called voltage vector control, so as to precisely control active and reactive power injected by the distributed generation units in a normal operation of the system, (grid-connected mode), and it works as a voltage source in an islanding mode. The adopted topology for the DG is the diode clamped multilevel inverter structure in order to minimize the injected harmonics and get rid of a sophisticated passive filter. The utilization of the voltage vector control scheme is optimized so that the DG unit can precisely control the instantaneous power injected to the power grid. The presented simulation results verify the capability of the suggested control to precisely adjust the active and reactive power based on set-values.
Research Interests:
Research Interests:
This paper investigates the performance of the multilevel, (5-level), diode clamped inverter in terms of the magnitude of the output voltage and harmonic spectrum of its output. This paper presents simulation results for the output... more
This paper investigates the performance of the multilevel, (5-level), diode clamped inverter in terms of the magnitude of the output voltage and harmonic spectrum of its output. This paper presents simulation results for the output voltage and how it can be controlled to get variable output voltage. Moreover, it introduces the harmonic content of the output voltage. In addition, the experimental results are also provided to prove and validate the simulation results. Finally, the correlation between the simulation results and experimental results are also presented.
Research Interests:
This paper shows the operation of the microgrid using a new adaptive PI controller based operational (control) scheme. The core of the proposed control scheme is the suggested adaptive PI controller. The parameters of the PI controller... more
This paper shows the operation of the microgrid using a new adaptive PI controller based operational (control) scheme. The core of the proposed control scheme is the suggested adaptive PI controller. The parameters of the PI controller are adaptively tuned using a variable step-size least mean fourth algorithm with no need for any system model to operate this adaptive controller. The main merit of the proposed scheme is that it stabilizes the magnitude and frequency of the voltage at any loading condition such as variable balanced loads, variable unbalanced loads, and nonlinear loads. The proposed scheme has a simple structure and accurate performance. In addition, the structure of proposed scheme provides a seamless transition toward any loss or reconnection of any inverter in the microgrid. Furthermore, the suggested operational scheme is flexible enough to enable the microgrid to be operative in a grid-connected mode and to transfer from the voltage control mode to power control ...
Research Interests:
This paper introduces a novel control scheme for the operation of multilevel inverters forming a microgrid. The core of the suggested control scheme is an advanced (power-rate) exponential sliding mode controller. This developed... more
This paper introduces a novel control scheme for the operation of multilevel inverters forming a microgrid. The core of the suggested control scheme is an advanced (power-rate) exponential sliding mode controller. This developed controller is robust toward any variation of the system’s parameters and loads in addition to its fast and accurate performance. The presented control scheme provides advantageous characteristics to the microgrid operation in an autonomous mode (microgrid mode) and grid-connected mode. In the microgrid mode, the voltages and frequency are stable at any variable balanced and unbalanced load. In the grid-connected mode, an effective procedure for connecting the microgrid to the main grid is proposed to guarantee a seamless and fast transition to the grid-connected mode. The performance of the presented control scheme along with its proposed controller is validated by comparing its results to another linear and non-linear controllers for the same microgrid load...
Research Interests:
This paper shows the operation of the distributed generation system using an innovative control scheme. The core of this distributed generation system is the distributed generator, which is based on the 5-level diode clamped inverter.... more
This paper shows the operation of the distributed generation system using an innovative control scheme. The core of this distributed generation system is the distributed generator, which is based on the 5-level diode clamped inverter. This distributed generator is operated by an improved version of the exponential sliding mode control. This developed sliding mode control perfectly fits the power electronics based distributed generator to control the output injected power, and it gives the shortest reaching time with much less chattering at its output power. The performance of the whole suggested control scheme along with the improved sliding mode controller is verified using simulation results.
Research Interests:
Research Interests:
This paper presents an improved application of Kalman Filter (KF) for estimating both symmetrical components of unbalanced voltage and current harmonics at the same time. In the proposed method, multi-output KF is developed instead of... more
This paper presents an improved application of Kalman Filter (KF) for estimating both symmetrical components of unbalanced voltage and current harmonics at the same time. In the proposed method, multi-output KF is developed instead of conventional single-output KF for each voltage and current phase. For the voltage, one multi-output KF is used rather than three separate KF to obtain the magnitude and the phase-shift for all the three phases together in one step and one term. Then, the instantaneous three phase voltages are represented in complex from which are required to obtain the symmetrical components. Meanwhile for the current, the current harmonics of the load are extracted for the three phases using also one multi-output KF. Both extracted disturbances are mitigated using Unified Power Quality Conditioner (UPQC). The performance of the proposed method is discussed and verified using simulation results by MATLAB/Simulink.
Research Interests:
This paper introduces the direct power control (DPC) scheme controlled by a new version of the 1st order sliding mode control to operate a distributed generator. This distributed generator is a core of the distributed generation system... more
This paper introduces the direct power control (DPC) scheme controlled by a new version of the 1st order sliding mode control to operate a distributed generator. This distributed generator is a core of the distributed generation system (DGS), which injects active and reactive power to the distribution system in a grid-connected mode. The presented 1st order sliding mode control based direct power scheme is very efficient in terms of chattering at steady-state and its dynamic performance. The superior performance of the presented control scheme results from a novel combination of an integral form for the sliding surface along with an innovative power-rate reaching law. The feedback power of the direct power scheme is estimated using an accurate developed formulation of the sliding mode observer. The distributed generator is based on the 5-level diode clamped inverter to minimize the injected harmonics. To prove the accurate performance of this new combination of the sliding mode cont...
Research Interests:
This paper presents a quantitative comparison between the multilevel inverters and conventional inverters. This paper manifests a descriptive comparison between the most widely used type of multilevel inverters and the most common type of... more
This paper presents a quantitative comparison between the multilevel inverters and conventional inverters. This paper manifests a descriptive comparison between the most widely used type of multilevel inverters and the most common type of conventional inverters are presented for this comparison. The 5-level diode clamped inverter is considered as a representative for multilevel inverters, and the 2-level unipolar inverter is a candidate for conventional inverters. Aforementioned inverters are compared with each other with respect to some characteristics: The output voltage, controllability of the output and its harmonic content. Simulation results are provided to show and verify the superior performance of the multilevel inverters to conventional inverters for the same operating condition. Moreover, one multilevel inverter and one conventional inverter are built in the lab. for a rating of 0.5 kVA to verify the findings given by simulation results.
Research Interests:
The purpose of this paper is to investigate the operation of single-phase induction generator as a standalone voltage source driven by variable speed turbine. The operation of the single-phase generator is studied under auxiliary applied... more
The purpose of this paper is to investigate the operation of single-phase induction generator as a standalone voltage source driven by variable speed turbine. The operation of the single-phase generator is studied under auxiliary applied AC voltage with and without series capacitor connected to this auxiliary winding as well as under self-excitation with initially charged capacitor. The paper presents a new model of the single-phase induction generator in the stationary reference frame fixed to the stator as well, the internal generated voltages in the main and auxiliary windings are modeled as voltage sources. The problem of harmonic voltages generation at most of the speed has been ensured; also, the resonance voltage problems due to existence of the series capacitor in the auxiliary winding circuit as well as the dc offset voltage in the generated voltage with self-excitation has been reported.
Abstract This article presents a new development for the decoupled state-feedback control to operate the distribution generation unit (DGU) within an efficient distribution generation system (DGS). The developed decoupled state-feedback... more
Abstract This article presents a new development for the decoupled state-feedback control to operate the distribution generation unit (DGU) within an efficient distribution generation system (DGS). The developed decoupled state-feedback is better than the conventional voltage vector control and sliding mode control for dealing with active and reactive power. Therefore, it is embraced to form a new control scheme, which is employed to effectively decouple and precisely control the injected active and reactive power to the distribution system. A five-level diode-clamped inverter is adopted to build the DGU in order to minimize the injected harmonics, facilitate the operation of the proposed control scheme, and ease the design of its passive filter. The proposed control scheme enables the DGS to be functional in several operational modes such as grid-connected, intentional islanding, unintentional islanding, anti-islanding, and ride-through modes. The effectiveness of the proposed control scheme is proved through the simulation results for all foregoing modes. Experimental results are provided to show how the proposed concepts are practically implemented to control the voltage of the DGU so that the active power and reactive power are exchanged between the power grid and the DGS in the grid-connected mode.
Research Interests:
This paper presents an innovative driver circuit for a new current regulator of the multilevel inverters. The proposed regulator has a PI controller to guarantee the optimum tracking for the reference current. This proposed regulator has... more
This paper presents an innovative driver circuit for a new current regulator of the multilevel inverters. The proposed regulator has a PI controller to guarantee the optimum tracking for the reference current. This proposed regulator has the advantage of integration between the PI controller and the multicarrier switching operation. This regulator fits the operation of multilevel and cascaded converters. The suggested current regulator is compared with several existing current regulators of the multilevel and cascaded converters. The performance of the proposed regulator is verified using simulation results in comparison with the performance of the common existing current regulators for the multilevel inverter. Moreover, this paper shows the performance of the new regulator in power system applications.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
This paper introduces an efficient technique for extracting the disturbance signal of the voltage flicker. The proposed technique, which depends on a novel modification of the adaptive perceptron technique, is controlled by the... more
This paper introduces an efficient technique for extracting the disturbance signal of the voltage flicker. The proposed technique, which depends on a novel modification of the adaptive perceptron technique, is controlled by the Widrow-Hoff delta rule. The extracted disturbance signal is employed for mitigating the cyclic voltage flicker by using series and parallel mitigating devices. The speed and accuracy of
Research Interests:
The growing interest in power quality has led to a variety of devices for mitigating power quality problems. This paper introduces a new integration between adaptive shunt active filter (ASAF) and three-phase dynamic voltage restorer... more
The growing interest in power quality has led to a variety of devices for mitigating power quality problems. This paper introduces a new integration between adaptive shunt active filter (ASAF) and three-phase dynamic voltage restorer (DVR), this integration is considered as a new power quality controller. This paper proposes a new control algorithm which takes care of all the current