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Papers by Hussein Al-Majali

International Journal of Electrical and Computer Engineering, Apr 1, 2022

The conventional three-phase alternating current (AC) to direct current (DC) converter can be mod... more The conventional three-phase alternating current (AC) to direct current (DC) converter can be modified using two isolated-gate bipolar transistor (IGBT) as bypass switches connected to tapping points on the secondary side of the transformer. This scheme yields a reduction in both harmonic contents and reactive volt-ampere absorption. This modified converter possibly eliminates the need for an on-load tap-changer on the converter transformer. The modified AC/DC converter is fully analyzed and implemented under balanced conditions using MATLAB-Simulink. The expressions of the output DC voltage are derived for different cases. The supply current harmonic contents, the reactive power absorption and the power factor have been compared for three schemes; the conventional bridge, the modified bridge using one bypass IGBT valve and the modified bridge with two bypass IGBT valves.

Electric Power Systems Research, Mar 1, 1999

ABSTRACT Direct current (DC) links are finding increasing use throughout the world in the form of... more ABSTRACT Direct current (DC) links are finding increasing use throughout the world in the form of long distance transmission and a synchronous interconnections. The objective of this paper is to present a new method to control the HVDC converter by modified series-connected bridges with GTO thyristor by-pass valves to give more reduction in both harmonics generation and reactive volt–ampere absorption for the rectifier and inverter modes of operation. Fast and continuous control of the DC voltage are possible using the proposed scheme, which uses by-pass GTO thyristor valves connected to tapping points on the secondary windings of the transformer for one bridge and the other one is operating as a conventional bridge.

2021 IEEE Jordan International Joint Conference on Electrical Engineering and Information Technology (JEEIT), 2021

Islanding detection is an important component in an inverters-based distributed generation to pro... more Islanding detection is an important component in an inverters-based distributed generation to provide the necessary protection function and manpower safety. Various anti-islanding detection techniques are presented in the literature. Passive techniques mainly have a large non-detection zone (NDZ). Active techniques have lower NDZ compared with passive methods, but it affects the power quality such as total harmonic distortion (THD). This paper presents a performance analysis of the active frequency drift technique (AFD). Additionally, this paper proposed a modified active frequency drift (AFD) to improve the THD and increase its sensitivity. The proposed method is analyzed mathematically and verified by simulation results. A single-phase grid connected photovoltaic system is modeled in MATLAB/Simulink program to analyze the proposed technique. the simulation result demonstrates that the proposed method improves the NDZ and reduces THD injected into the system.

International Journal of Engineering Trends and Technology, 2021

2021 IEEE Jordan International Joint Conference on Electrical Engineering and Information Technology (JEEIT), 2021

Lately, the implementation of distributed energies generation has increased and developed quickly... more Lately, the implementation of distributed energies generation has increased and developed quickly. Intermittent generation leads to instability in the power grid, which creates variations in the power network voltage and frequency, and with the implementation of renewable sources, energy storage will play a crucial part in the Smart Grid. This technology has been shown to be capable of providing and improving the quality of the power system and to support valuable advantages in a variety of forms. Energy storage systems (ESSs) especially battery energy storage systems (BESSs), have recently attracted considerable activity in the electricity industry as an effective solution to alleviate the drawbacks of renewable energy systems. This paper addresses utilizing the Particle Swarm Optimization (PSO) algorithm to obtain the BESS operation in the integrated distribution network for the photovoltaic generation to mitigate the problem of voltage deviation. The efficacy of the proposed approach which is implemented in MATLAB/SIMULINK is verified by applying the PSO algorithm and power flow analysis to the modified IEEE 9-bus power system. The simulation results indicate that the PSO with power flow calculation is successful in determining the optimal BESS operation to minimize the voltage deviation.

Journal of Hunan University Natural Sciences, Feb 28, 2022

International Journal of Engineering Trends and Technology, 2021

International Journal of Electrical and Computer Engineering (IJECE), 2022

The conventional three-phase alternating current (AC) to direct current (DC) converter can be mod... more The conventional three-phase alternating current (AC) to direct current (DC) converter can be modified using two isolated-gate bipolar transistor (IGBT) as by-pass switches connected to tapping points on the secondary side of the transformer. This scheme yields a reduction in both harmonic contents and reactive volt-ampere absorption. This modified converter possibly eliminates the need for an on-load tap-changer on the converter transformer. The modified AC/DC converter is fully analyzed and implemented under balanced conditions using MATLAB-Simulink. The expressions of the output DC voltage are derived for different cases. The supply current harmonic contents, the reactive power absorption and the power factor have been compared for three schemes; the conventional bridge, the modified bridge using one by-pass IGBT valve and the modified bridge with two by-pass IGBT valves.

2019 IEEE Jordan International Joint Conference on Electrical Engineering and Information Technology (JEEIT), 2019

In this paper, three different current controllers that are tuned using different optimal tuning ... more In this paper, three different current controllers that are tuned using different optimal tuning criterion are applied and tested for the operation of the voltage-source converter (VSC) under weak AC grid connection. The implemented controllers include the PI controller in the dqdqdq frame, the PR controller in the alphabeta\alpha \betaalphabeta -frame, and the hysteresis controller in the abc-frame. The current controllers’ gains have been optimally tuned using both analytical and evolutionary stochastic algorithms. The simulation setup is carried on Matlab/Simulink platform, and the results are assessed based on five metrics criteria; these include the rising time, the settling time, the percentage overshoot, the steady-state fluctuation, and the stability during a three-phase symmetrical fault.

Unbalance in the operation of AC/DC converters gives rise to abnormal or uncharacteristic current... more Unbalance in the operation of AC/DC converters gives rise to abnormal or uncharacteristic current harmonics, in addition to the characteristic harmonics in the supply current waveforms. This paper concentrates on the analysis of uncharacteristic harmonics caused by unbalanced AC supply voltages. Attention is given to modified converter operation which uses thyristors connected to tapping points on the secondary windings of the transformer. Control of by-pass thyristor for reducing abnormal harmonic generation are discusses, and some experimental results supporting the theoretical calculations are also included.

WSEAS TRANSACTIONS ON SYSTEMS AND CONTROL, 2020

Control of a conventional converter station which uses a three-phase controlled bridge for conver... more Control of a conventional converter station which uses a three-phase controlled bridge for converting AC to DC and vice-versa is achieved by fast-acting control of the valve firing angles. Tap-changers which are fitted on the converter transformer provide a near constant AC voltage input to the bridge to correct relatively slow changes of AC voltage. This paper describe a modification of the conventional bridge circuit, using by-pass valves connected to tapping points on the secondary winding of the transformer. This scheme permits a wide range of voltage control with a reduction in both the harmonic generation and the reactive voltampere absorption, and possibly eliminates the need for an on-load tap-changer on the converter transformer. Experimental results on a laboratory model compare well with the predicted values.

Three-phase controlled rectifiers have a wide range of applications, from small rectifier to larg... more Three-phase controlled rectifiers have a wide range of applications, from small rectifier to large high voltage direct current (HVDC) transmission systems which are increasingly used throughout the world for long distance transmission and asynchronous interconnection. The transient performance of an HVDC power system is highly dependent on the parameters of the current/voltage regulators of the converter controls. This paper describes an alternative application of conventional bridge circuits using series connected bridges, of dissimilar rating, with different firing angles. Both steady-state and transient operations are presented. The experimental and analytically results are compared.

Unbalance in the AC/DC converters produce uncharacteristic current harmonics, in addition to the ... more Unbalance in the AC/DC converters produce uncharacteristic current harmonics, in addition to the characteristic harmonics in the AC waveform not expected from the balanced operation. In this paper a three-phase AC-DC converter is fully analyzed and the performance of the converter under balanced and unbalanced conditions is evaluated. Also, the relationship between unbalance factor (UBF) and the resultant harmonics is investigated. Method of reducing uncharacteristic harmonic generation through firing angle modulation is discussed. A digital trigger scheme control circuit for valves with individual control circuit for each device has been designed and built. A digital computer simulation program based on this method is developed, and some experimental results are also given.

IEEE Transactions on Power Electronics, 1998

A three-phase bridge for a high-voltage direct-current (HVDC) converter which uses auxiliary (byp... more A three-phase bridge for a high-voltage direct-current (HVDC) converter which uses auxiliary (bypass) thyristor valves connected to tapping points on the transformer secondary windings has been previously described. The performance is enhanced by using self- or force-commutated devices for these valves, and three different schemes are examined. Experimental tests on a laboratory model validate the theoretical results. Fast and continuous

Electric Power Systems Research, 2007

The bridge circuit used in high voltage direct current (HVDC) converters may be modified by inclu... more The bridge circuit used in high voltage direct current (HVDC) converters may be modified by including bypass thyristor valves connected to tapping points on the secondary windings of the transformer to give a reduction in both harmonic generation and reactive volt-ampere absorption for the rectifier and inverter modes of operation. In this paper, control strategies for the transient response of the HVDC converter with either thyristor or GTO thyristor bypass valves are investigated using several types of firing angle control logic. Fast and continuous control of the DC voltage is possible using the proposed scheme without the conventional on load tap-changer on the converter transformer. Experimental results on a laboratory model compare well with the predicted values.

Electric Power Systems Research, 1997

High voltage direct current (HVDC) power transmission systems constitute an important application... more High voltage direct current (HVDC) power transmission systems constitute an important application of power electronics technology. This article presents a new method to control the HVDC converters by modified series-connected bridges to give a reduction in both harmonic generation and reactive volt-ampere absorption for the rectifier and inverter modes of operation. Moreover. a voltage control scheme is proposed which uses bypass thyristor valves connected to tapping points on the secondary windings of the transformer for one bridge with the other one operating as a conventional bridge. Fast and continuous control of the DC voltage are possible using the proposed scheme without the conventional on load-tap changer on the converter transformer.

International Journal of Electrical and Computer Engineering, Apr 1, 2022

The conventional three-phase alternating current (AC) to direct current (DC) converter can be mod... more The conventional three-phase alternating current (AC) to direct current (DC) converter can be modified using two isolated-gate bipolar transistor (IGBT) as bypass switches connected to tapping points on the secondary side of the transformer. This scheme yields a reduction in both harmonic contents and reactive volt-ampere absorption. This modified converter possibly eliminates the need for an on-load tap-changer on the converter transformer. The modified AC/DC converter is fully analyzed and implemented under balanced conditions using MATLAB-Simulink. The expressions of the output DC voltage are derived for different cases. The supply current harmonic contents, the reactive power absorption and the power factor have been compared for three schemes; the conventional bridge, the modified bridge using one bypass IGBT valve and the modified bridge with two bypass IGBT valves.

Electric Power Systems Research, Mar 1, 1999

ABSTRACT Direct current (DC) links are finding increasing use throughout the world in the form of... more ABSTRACT Direct current (DC) links are finding increasing use throughout the world in the form of long distance transmission and a synchronous interconnections. The objective of this paper is to present a new method to control the HVDC converter by modified series-connected bridges with GTO thyristor by-pass valves to give more reduction in both harmonics generation and reactive volt–ampere absorption for the rectifier and inverter modes of operation. Fast and continuous control of the DC voltage are possible using the proposed scheme, which uses by-pass GTO thyristor valves connected to tapping points on the secondary windings of the transformer for one bridge and the other one is operating as a conventional bridge.

2021 IEEE Jordan International Joint Conference on Electrical Engineering and Information Technology (JEEIT), 2021

Islanding detection is an important component in an inverters-based distributed generation to pro... more Islanding detection is an important component in an inverters-based distributed generation to provide the necessary protection function and manpower safety. Various anti-islanding detection techniques are presented in the literature. Passive techniques mainly have a large non-detection zone (NDZ). Active techniques have lower NDZ compared with passive methods, but it affects the power quality such as total harmonic distortion (THD). This paper presents a performance analysis of the active frequency drift technique (AFD). Additionally, this paper proposed a modified active frequency drift (AFD) to improve the THD and increase its sensitivity. The proposed method is analyzed mathematically and verified by simulation results. A single-phase grid connected photovoltaic system is modeled in MATLAB/Simulink program to analyze the proposed technique. the simulation result demonstrates that the proposed method improves the NDZ and reduces THD injected into the system.

International Journal of Engineering Trends and Technology, 2021

2021 IEEE Jordan International Joint Conference on Electrical Engineering and Information Technology (JEEIT), 2021

Lately, the implementation of distributed energies generation has increased and developed quickly... more Lately, the implementation of distributed energies generation has increased and developed quickly. Intermittent generation leads to instability in the power grid, which creates variations in the power network voltage and frequency, and with the implementation of renewable sources, energy storage will play a crucial part in the Smart Grid. This technology has been shown to be capable of providing and improving the quality of the power system and to support valuable advantages in a variety of forms. Energy storage systems (ESSs) especially battery energy storage systems (BESSs), have recently attracted considerable activity in the electricity industry as an effective solution to alleviate the drawbacks of renewable energy systems. This paper addresses utilizing the Particle Swarm Optimization (PSO) algorithm to obtain the BESS operation in the integrated distribution network for the photovoltaic generation to mitigate the problem of voltage deviation. The efficacy of the proposed approach which is implemented in MATLAB/SIMULINK is verified by applying the PSO algorithm and power flow analysis to the modified IEEE 9-bus power system. The simulation results indicate that the PSO with power flow calculation is successful in determining the optimal BESS operation to minimize the voltage deviation.

Journal of Hunan University Natural Sciences, Feb 28, 2022

International Journal of Engineering Trends and Technology, 2021

International Journal of Electrical and Computer Engineering (IJECE), 2022

The conventional three-phase alternating current (AC) to direct current (DC) converter can be mod... more The conventional three-phase alternating current (AC) to direct current (DC) converter can be modified using two isolated-gate bipolar transistor (IGBT) as by-pass switches connected to tapping points on the secondary side of the transformer. This scheme yields a reduction in both harmonic contents and reactive volt-ampere absorption. This modified converter possibly eliminates the need for an on-load tap-changer on the converter transformer. The modified AC/DC converter is fully analyzed and implemented under balanced conditions using MATLAB-Simulink. The expressions of the output DC voltage are derived for different cases. The supply current harmonic contents, the reactive power absorption and the power factor have been compared for three schemes; the conventional bridge, the modified bridge using one by-pass IGBT valve and the modified bridge with two by-pass IGBT valves.

2019 IEEE Jordan International Joint Conference on Electrical Engineering and Information Technology (JEEIT), 2019

In this paper, three different current controllers that are tuned using different optimal tuning ... more In this paper, three different current controllers that are tuned using different optimal tuning criterion are applied and tested for the operation of the voltage-source converter (VSC) under weak AC grid connection. The implemented controllers include the PI controller in the dqdqdq frame, the PR controller in the alphabeta\alpha \betaalphabeta -frame, and the hysteresis controller in the abc-frame. The current controllers’ gains have been optimally tuned using both analytical and evolutionary stochastic algorithms. The simulation setup is carried on Matlab/Simulink platform, and the results are assessed based on five metrics criteria; these include the rising time, the settling time, the percentage overshoot, the steady-state fluctuation, and the stability during a three-phase symmetrical fault.

Unbalance in the operation of AC/DC converters gives rise to abnormal or uncharacteristic current... more Unbalance in the operation of AC/DC converters gives rise to abnormal or uncharacteristic current harmonics, in addition to the characteristic harmonics in the supply current waveforms. This paper concentrates on the analysis of uncharacteristic harmonics caused by unbalanced AC supply voltages. Attention is given to modified converter operation which uses thyristors connected to tapping points on the secondary windings of the transformer. Control of by-pass thyristor for reducing abnormal harmonic generation are discusses, and some experimental results supporting the theoretical calculations are also included.

WSEAS TRANSACTIONS ON SYSTEMS AND CONTROL, 2020

Control of a conventional converter station which uses a three-phase controlled bridge for conver... more Control of a conventional converter station which uses a three-phase controlled bridge for converting AC to DC and vice-versa is achieved by fast-acting control of the valve firing angles. Tap-changers which are fitted on the converter transformer provide a near constant AC voltage input to the bridge to correct relatively slow changes of AC voltage. This paper describe a modification of the conventional bridge circuit, using by-pass valves connected to tapping points on the secondary winding of the transformer. This scheme permits a wide range of voltage control with a reduction in both the harmonic generation and the reactive voltampere absorption, and possibly eliminates the need for an on-load tap-changer on the converter transformer. Experimental results on a laboratory model compare well with the predicted values.

Three-phase controlled rectifiers have a wide range of applications, from small rectifier to larg... more Three-phase controlled rectifiers have a wide range of applications, from small rectifier to large high voltage direct current (HVDC) transmission systems which are increasingly used throughout the world for long distance transmission and asynchronous interconnection. The transient performance of an HVDC power system is highly dependent on the parameters of the current/voltage regulators of the converter controls. This paper describes an alternative application of conventional bridge circuits using series connected bridges, of dissimilar rating, with different firing angles. Both steady-state and transient operations are presented. The experimental and analytically results are compared.

Unbalance in the AC/DC converters produce uncharacteristic current harmonics, in addition to the ... more Unbalance in the AC/DC converters produce uncharacteristic current harmonics, in addition to the characteristic harmonics in the AC waveform not expected from the balanced operation. In this paper a three-phase AC-DC converter is fully analyzed and the performance of the converter under balanced and unbalanced conditions is evaluated. Also, the relationship between unbalance factor (UBF) and the resultant harmonics is investigated. Method of reducing uncharacteristic harmonic generation through firing angle modulation is discussed. A digital trigger scheme control circuit for valves with individual control circuit for each device has been designed and built. A digital computer simulation program based on this method is developed, and some experimental results are also given.

IEEE Transactions on Power Electronics, 1998

A three-phase bridge for a high-voltage direct-current (HVDC) converter which uses auxiliary (byp... more A three-phase bridge for a high-voltage direct-current (HVDC) converter which uses auxiliary (bypass) thyristor valves connected to tapping points on the transformer secondary windings has been previously described. The performance is enhanced by using self- or force-commutated devices for these valves, and three different schemes are examined. Experimental tests on a laboratory model validate the theoretical results. Fast and continuous

Electric Power Systems Research, 2007

The bridge circuit used in high voltage direct current (HVDC) converters may be modified by inclu... more The bridge circuit used in high voltage direct current (HVDC) converters may be modified by including bypass thyristor valves connected to tapping points on the secondary windings of the transformer to give a reduction in both harmonic generation and reactive volt-ampere absorption for the rectifier and inverter modes of operation. In this paper, control strategies for the transient response of the HVDC converter with either thyristor or GTO thyristor bypass valves are investigated using several types of firing angle control logic. Fast and continuous control of the DC voltage is possible using the proposed scheme without the conventional on load tap-changer on the converter transformer. Experimental results on a laboratory model compare well with the predicted values.

Electric Power Systems Research, 1997

High voltage direct current (HVDC) power transmission systems constitute an important application... more High voltage direct current (HVDC) power transmission systems constitute an important application of power electronics technology. This article presents a new method to control the HVDC converters by modified series-connected bridges to give a reduction in both harmonic generation and reactive volt-ampere absorption for the rectifier and inverter modes of operation. Moreover. a voltage control scheme is proposed which uses bypass thyristor valves connected to tapping points on the secondary windings of the transformer for one bridge with the other one operating as a conventional bridge. Fast and continuous control of the DC voltage are possible using the proposed scheme without the conventional on load-tap changer on the converter transformer.