Hisham Soliman - Academia.edu (original) (raw)

Papers by Hisham Soliman

Sensors

System stability deterioration in microgrids commonly occurs due to unpredictable faults and equi... more System stability deterioration in microgrids commonly occurs due to unpredictable faults and equipment malfunctions. Recently, robust control techniques have been used in microgrid systems to address these difficulties. In this paper, for DC-islanded microgrids that have sensors faults, a new passive fault-tolerant control strategy is developed. The suggested approach can be used to maintain system stability in the presence of flaws, such as faulty actuators and sensors, as well as component failures. The suggested control is effective when the fault is never recognized (or when the fault is not being precisely known, and some ambiguity in the fault may be interpreted as uncertainty in the system’s dynamics following the fault). The design is built around a derived sufficient condition in the context of linear matrix inequalities (LMIs) and the attractive ellipsoid technique. The ellipsoidal stabilization idea is to bring the state trajectories into a small region including the orig...

Energies

A photovoltaic generator connected to a large network and supplying a nonlinear load (source of h... more A photovoltaic generator connected to a large network and supplying a nonlinear load (source of harmonics) injects distorted current into the grid. This manuscript presents an invariant-ellipsoid set design of a robust controlled active power filter to inject current into the large grid with minimum total harmonic distortion (THD). The nonlinear load current is considered an external disturbance to minimize its effect on the injected grid current. Moreover, the large grid is modeled as a fixed voltage source in a series with a Thevenin impedance whose value changes within an interval. Using the invariant-ellipsoid technique, the problem is cast as a robust disturbance-rejection tracking control. The volume of the ellipsoid is minimized, which results in minimizing the effect of disturbance on system performance and keeping the trajectories as close as possible to the origin. The design is cast into a set of nonlinear matrix inequalities that are linearized by fixing a scalar. The re...

This chapter deals with the problem of state feedback control for an active quarter-car suspensio... more This chapter deals with the problem of state feedback control for an active quarter-car suspension system with control input constraint. The dynamics of the suspension system is first formed in terms of the control objectives: ride comfort, suspension deflection, and maximum actuator control force. The control task is formulated as robustly placing the closed poles in a desired region against different passenger load. Since digital computers are widely used in the vehicle industry, a new saturated controller design method is presented for regional pole-placement of uncertain discrete time systems. The constraint of control input saturation is considered in the design phase. The desired dynamic performance for uncertain discrete-time systems is represented by the settling time and damping ratio. A sufficient condition is derived to place the poles in a desired region. The design is formulated in terms of linear matrix inequality optimization. The effectiveness of the proposed design is illustrated by applying it to a quarter-car active suspension system. Different road tests for the proposed controller are carried out: step and bump disturbances. The proposed design achieves the desired oscillation damping due to road disturbances in addition to passenger comfort. The results are compared with the passive suspension system.

IEEE Access, 2021

Recently the integration of renewable energy resources to direct-current microgrids has become a ... more Recently the integration of renewable energy resources to direct-current microgrids has become a hot research topic. The voltage stability problem is of paramount importance when the system is subject to external disturbances, parameters uncertainties, and plug-and-play regimes. This paper introduces a novel decentralized voltage tracking for a direct-current islanded microgrid. It consists of numerous Distributed Generation units. The decentralized controller of each distributed generator adjusts the voltage at the point of common coupling to track the desired reference. The proposed control copes with the plugand-play operation of the microgrid. This means that the possibility of connection /disconnection distributed generators without deteriorating the stability of the overall microgrid is done through the invariant ellipsoid set and the linear matrix inequality optimization. Another merit of the proposed control is that updating the rest of the controllers is not required when a distributed generator is plugged in or out. Moreover, the proposed decentralized controller just uses local states (information) of its distributed generator only. Many simulations and practical studies with different scenarios have been conducted in this paper to verify the performance of the proposed controllers. Comparison with the existing schemes is included. INDEX TERMS DC microgrid, disturbance attenuation, parametric uncertainty, state-feedback robust control, voltage tracker. FARAG ALI EL-SHEIKHI received the M.Sc. degree in the area of power system simulation from the University of Missouri, Columbia, USA, and the Ph.D. degree in the area of power systems reliability evaluation from the University of Saskatchewan, Canada. He was a Professor of electrical energy and power system reliability with the University of Benghazi, Libya. He is currently a Teaching Staff with the Electrical and Elec

The Journal of Engineering Research [TJER], 2019

The use of power system stabilizers (PSSs) to damp power system swing mode oscillations is of ext... more The use of power system stabilizers (PSSs) to damp power system swing mode oscillations is of extreme practical importance. This manuscript presents an approach to the stabilization of a single machine infinite bus system (SMIB). The proposed control is based on the notch-filter approach to cancel the poles near to the imaginary axes. The approach is based on the root locus method. Application to Barka II power station connected to the main interconnected system of Oman is presented. The peak load at summer is considered as the system is near to instability. The Barka SMIB is modeled as a fourth order non-linear system. A linearized model is then obtained using MATLAB/Simulink. The simulation results validate the proposed design for the PSS.

The question of loyalty in autocratic regimes has drawn a sustained scholarly interest, especiall... more The question of loyalty in autocratic regimes has drawn a sustained scholarly interest, especially with the resilience of many of these regimes over most of world history and over the past few decades in particular. Autocratic leaders need to secure the support of their militaries to survive in office and to minimize the risk of a coup. Among the commonly employed mechanisms in this regard is the extension of extra-budgetary financial rewards, including ‘Military-Owned Businesses (MOBs).’ Nevertheless, under the increasingly significant threat of an uprising from below, military defection remains the key for the success of the revolution. The question then becomes: under what conditions would a military defect from an autocratic ruling alliance? Although many answers have been proposed to solve this puzzle, an increasing number of cases are proving them insufficient. Alternatively, this project presents one novel answer to this question, which is: militaries are “defection-proofed” ...

Arabian Journal for Science and Engineering, 2020

This manuscript introduces a new robust control design of car active suspension systems using ell... more This manuscript introduces a new robust control design of car active suspension systems using ellipsoidal techniques. The impact of road irregularities is regarded as an external disturbance. The suggested controller meets the following objectives: optimal passenger comfort, actuator control force limit satisfaction, effective disturbance rejection, and robustness against changes in passengers' load. The passenger load variations cause system uncertainty that is modeled as norm-bounded. A new sufficient condition is established based on the invariant ellipsoid method and the linear matrix inequalities optimization to guarantee robust stability and performance for the system. Time-domain model of road roughness based on trigonometric functions is studied. The performance of the proposed controller is tested using a quarter-car model with an active suspension system. Comparative simulation with other techniques, e.g., H ∞ and regional pole placement, is given. Actuator dynamics and system nonlinearities are modeled and included in the design at the end.

This study addresses the issue of photovoltaic (PV) systems optimal allocation in electric distri... more This study addresses the issue of photovoltaic (PV) systems optimal allocation in electric distribution network. A case study of using particle swarm optimization (PSO) and genetic algorithms (GA) is presented. The objective function of the problem is to minimize system losses while improving voltage profile. The study considers the network of Masirah Island, Oman, as a case study system. The study includes two stages. In the first stage, the test system is modeled and simulated using the MATLAB load flow toolbox. In the second stage, both PSO and GA optimization tools are used to find the optimal allocation of PV systems. Both algorithms resulted in similar values for both the objective function value and decision variables. Simulation results shows that technical real power losses represent 2.1% of the total load. However, the optimal allocation of PV systems at five buses can reduce losses by 50%.

World Journal of Social Science Research, 2021

The question of loyalty in autocratic regimes has drawn a sustained scholarly interest, especiall... more The question of loyalty in autocratic regimes has drawn a sustained scholarly interest, especially as autocratic leaders need to secure the support of their militaries to survive in office and to minimize the risk of a coup. Among the commonly employed mechanisms in this regard is the extension of extra-budgetary financial rewards, including “Military-Owned Businesses (MOBs)”. Nevertheless, under the increasingly significant threat of an uprising from below, military defection remains the key for the success of the revolution. The question then becomes: under what conditions would a military defect from an autocratic ruling alliance? This paper presents one novel answer to this question, which is: militaries are “defection-proofed” in the face of mass uprisings when they develop financial dependency on the regime. This hypothesis is tested comparatively against the cases of mass protests in China (1989), Indonesia (1998), Thailand (2006), and Iran (2009).

Saudi Medical Journal, Mar 1, 2007

To evaluate the prevalence of refluxing pelvic veins among female patients with lower extremity v... more To evaluate the prevalence of refluxing pelvic veins among female patients with lower extremity varicose veins and the role of embolization treatment in these cases. Of 158 female patients suffering from primary varicose veins of the lower extremities presented to the Venous Disease Clinic at Dhahran Health Center between January 2002 and December 2004, 25 patients (15.8%) were noted to have vulvar or postero-medial thigh varices or both. Those were referred for trans-jugular descending pelvic venography with or without subsequent embolization of the contributing refluxing veins. Venous reflux contributing to the vulvoperineal or posterior thigh varices was detected in 23 patients (92%) on catheter venography. Left ovarian venous reflux was responsible for 60% of all cases. Embolization, using multiple coils, was successful in 18 patients with positive reflux (78.3%). One patient had primary vulvar venous malformation that required additional percutaneous sclerotherapy using dehydrated ethanol. Four patients had femoro-saphenous reflux contributing to the varices and required subsequent surgical ligation excision. All treated cases showed significant improvement of their symptoms without any procedure related complications. In patients with vulvar or postero-medial thigh varicose veins, radiological study of ovarian and hypogastric venous reflux should be considered. Trans-jugular descending venography and embolization is a feasible, effective and safe diagnostic and therapeutic modality.

Electric Power Components and Systems, 2009

ABSTRACT This article presents the design technique of an adaptive power system stabilizer using ... more ABSTRACT This article presents the design technique of an adaptive power system stabilizer using adaptive neuro-fuzzy inference systems trained via data obtained from genetic algorithms. The parameters of a standard power system stabilizer are tuned using adaptive neuro-fuzzy inference systems to achieve a certain damping ratio and settling time at all load points within a wide region of operation. The overall transfer function of the system is derived in terms of the power system stabilizer parameters. A genetic algorithm is used to minimize a multi-objective optimization function that forces the damping ratio and settling time of the system to desired values. The optimization process is separately conducted at selected operating points to yield power system stabilizer parameters that change with load variations. Results of genetic algorithm optimization are used to form a training dataset of an adaptive neuro-fuzzy inference systems agent, which could give the power system stabilizer parameters at any load within the specified region of operation. Results of power system stabilizer testing show that the desired performance indices could be fulfilled from light load to over load under both lagging and leading power factor conditions. System performance shows a remarkable improvement of dynamic stability by obtaining a well-damped time response.

Computers & Electrical Engineering, 1984

This paper considers the problem of stabilizing the dynamics of a large electric power system, re... more This paper considers the problem of stabilizing the dynamics of a large electric power system, represented by a linear time invariant system of equations, by using several decentralized (or local) state feedback control laws. The stabilization problem is formulated into a functional minimization problem which implicitly controls the closed-loop eigenvalues of the controlled system. The constraint of decentralization is tackled in the minimization algorithm by using the method of feasible directions. To illustrate the application of the algorithm, it is used to stabilize a three machine electric power system.

Energies

This paper deals with a discrete-time stochastic control model design for random failure prone an... more This paper deals with a discrete-time stochastic control model design for random failure prone and maintenance in a single machine infinite bus (SMIB) system. This model includes the practical values of failure/repair rate of transmission lines and transformers. The probability matrix is, therefore, calculated accordingly. The model considers two extreme modes of operations: the most reliable mode and the least reliable contingency case. This allows the control design which stochastically stabilizes the system under jump Markov disturbances. For adequate transient response, the proposed state feedback power system stabilizer (PSS) achieves a desired settling time and damping ratio by placing the closed-loop poles in a desired region. The control target should also be satisfied for load variations in either mode of operation. A sufficient condition is developed to achieve the control objectives via solving a set of linear matrix inequalities (LMI). Using simulation, the performance o...

MEJ. Mansoura Engineering Journal, 2021

Particulate Science and Technology, 2018

A nominal calcium silicate was prepared through wet route and investigated as sorbent for the rem... more A nominal calcium silicate was prepared through wet route and investigated as sorbent for the removal of long-lived radionuclides 134 Cs and 152 þ 154 Eu from aqueous solutions. The physicochemical properties of the prepared nonmaterial such as FT-IR, SEM, XRD and TEM were examined. Sorption of both 134 Cs and 152 þ 154 Eu onto the nanomaterial from aqueous solutions was evaluated in a consignment technique with regard to the temperature, pH and contact time. The kinetics of adsorption of 134 Cs and 152 þ 154 Eu have been discussed using three kinetic models namely, pseudo-first-order, pseudo-second-order and Elovich models. The results designated that the second-order model could describe the sorption kinetics for the two metal ions. The present work launches a new trend of research by considering the nano-calcium silicate as an engineered barrier around the disposal facilities at the nuclear activity centers.

TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES, 2016

Steam valve control is usually discarded in power system stability due to belief in its slow resp... more Steam valve control is usually discarded in power system stability due to belief in its slow response. The present manuscript makes use of it as a backup control in the case of failure of the main fast excitation control. The model describing system dynamics as a function of the two controllers, with wide range loading conditions, is derived in a norm-bounded format. Linear matrix inequalities are derived as a sufficient condition to obtain reliable controllers that provide good oscillation damping when both controllers are sound or even in the case of failure of either one. The design scheme is robust in the sense that it keeps reliable stability against wide load changes as well. A single machine infinite bus system is presented to illustrate the proposed design procedure and exhibit its performance. Results of excitation and governor controller testing show that the desired performance could be fulfilled from light load to heavy load conditions. System performance shows a remarkable improvement of dynamic stability by obtaining a well-damped oscillation time response even in the case of failure of either controller. Extension of the proposed controller to multiarea load-frequency control with time delay is also presented.

International Journal of Electrical Power & Energy Systems, 2015

In this paper, a new saturated control design for uncertain power systems is proposed. The develo... more In this paper, a new saturated control design for uncertain power systems is proposed. The developed saturated control scheme is based on linear matrix inequality (LMI) optimization to achieve prescribed dynamic performance measures, e.g., settling time and damping ratio. In this design, the closed-loop poles are forced to lie within a desired region. The proposed design provides robustness against system uncertainties. The simulation results of both a single machine infinite bus and a multi-machine power systems are given to validate the effectiveness of the proposed controller.

IEEE Transactions on Smart Grid, 2014

We study the demand side management (DSM) problem when customers are equipped with energy storage... more We study the demand side management (DSM) problem when customers are equipped with energy storage devices. Two games are discussed: the first is a non-cooperative one played between the residential energy consumers, while the second is a Stackelberg game played between the utility provider and the energy consumers. We introduce a new cost function applicable to the case of users selling back stored energy. The non-cooperative energy consumption game is played between users who schedule their energy use to minimize energy cost. The game is shown to have a unique Nash equilibrium, that is also the global system optimal point. In the Stackelberg game, the utility provider sets the prices to maximize its profit knowing that users will respond by minimizing their cost. We provide existence and uniqueness results for the Stackelberg equilibrium. The Stackelberg game is shown to be the general case of the minimum Peak-to-Average power ratio (PAR) problem. Two algorithms, centralized and distributed, are presented to solve the Stackelberg game. We present results that elucidate the interplay between storage capacity, energy requirements, number of users and system performance measured in total cost and peak-to-average power ratio (PAR).

Sensors

System stability deterioration in microgrids commonly occurs due to unpredictable faults and equi... more System stability deterioration in microgrids commonly occurs due to unpredictable faults and equipment malfunctions. Recently, robust control techniques have been used in microgrid systems to address these difficulties. In this paper, for DC-islanded microgrids that have sensors faults, a new passive fault-tolerant control strategy is developed. The suggested approach can be used to maintain system stability in the presence of flaws, such as faulty actuators and sensors, as well as component failures. The suggested control is effective when the fault is never recognized (or when the fault is not being precisely known, and some ambiguity in the fault may be interpreted as uncertainty in the system’s dynamics following the fault). The design is built around a derived sufficient condition in the context of linear matrix inequalities (LMIs) and the attractive ellipsoid technique. The ellipsoidal stabilization idea is to bring the state trajectories into a small region including the orig...

Energies

A photovoltaic generator connected to a large network and supplying a nonlinear load (source of h... more A photovoltaic generator connected to a large network and supplying a nonlinear load (source of harmonics) injects distorted current into the grid. This manuscript presents an invariant-ellipsoid set design of a robust controlled active power filter to inject current into the large grid with minimum total harmonic distortion (THD). The nonlinear load current is considered an external disturbance to minimize its effect on the injected grid current. Moreover, the large grid is modeled as a fixed voltage source in a series with a Thevenin impedance whose value changes within an interval. Using the invariant-ellipsoid technique, the problem is cast as a robust disturbance-rejection tracking control. The volume of the ellipsoid is minimized, which results in minimizing the effect of disturbance on system performance and keeping the trajectories as close as possible to the origin. The design is cast into a set of nonlinear matrix inequalities that are linearized by fixing a scalar. The re...

This chapter deals with the problem of state feedback control for an active quarter-car suspensio... more This chapter deals with the problem of state feedback control for an active quarter-car suspension system with control input constraint. The dynamics of the suspension system is first formed in terms of the control objectives: ride comfort, suspension deflection, and maximum actuator control force. The control task is formulated as robustly placing the closed poles in a desired region against different passenger load. Since digital computers are widely used in the vehicle industry, a new saturated controller design method is presented for regional pole-placement of uncertain discrete time systems. The constraint of control input saturation is considered in the design phase. The desired dynamic performance for uncertain discrete-time systems is represented by the settling time and damping ratio. A sufficient condition is derived to place the poles in a desired region. The design is formulated in terms of linear matrix inequality optimization. The effectiveness of the proposed design is illustrated by applying it to a quarter-car active suspension system. Different road tests for the proposed controller are carried out: step and bump disturbances. The proposed design achieves the desired oscillation damping due to road disturbances in addition to passenger comfort. The results are compared with the passive suspension system.

IEEE Access, 2021

Recently the integration of renewable energy resources to direct-current microgrids has become a ... more Recently the integration of renewable energy resources to direct-current microgrids has become a hot research topic. The voltage stability problem is of paramount importance when the system is subject to external disturbances, parameters uncertainties, and plug-and-play regimes. This paper introduces a novel decentralized voltage tracking for a direct-current islanded microgrid. It consists of numerous Distributed Generation units. The decentralized controller of each distributed generator adjusts the voltage at the point of common coupling to track the desired reference. The proposed control copes with the plugand-play operation of the microgrid. This means that the possibility of connection /disconnection distributed generators without deteriorating the stability of the overall microgrid is done through the invariant ellipsoid set and the linear matrix inequality optimization. Another merit of the proposed control is that updating the rest of the controllers is not required when a distributed generator is plugged in or out. Moreover, the proposed decentralized controller just uses local states (information) of its distributed generator only. Many simulations and practical studies with different scenarios have been conducted in this paper to verify the performance of the proposed controllers. Comparison with the existing schemes is included. INDEX TERMS DC microgrid, disturbance attenuation, parametric uncertainty, state-feedback robust control, voltage tracker. FARAG ALI EL-SHEIKHI received the M.Sc. degree in the area of power system simulation from the University of Missouri, Columbia, USA, and the Ph.D. degree in the area of power systems reliability evaluation from the University of Saskatchewan, Canada. He was a Professor of electrical energy and power system reliability with the University of Benghazi, Libya. He is currently a Teaching Staff with the Electrical and Elec

The Journal of Engineering Research [TJER], 2019

The use of power system stabilizers (PSSs) to damp power system swing mode oscillations is of ext... more The use of power system stabilizers (PSSs) to damp power system swing mode oscillations is of extreme practical importance. This manuscript presents an approach to the stabilization of a single machine infinite bus system (SMIB). The proposed control is based on the notch-filter approach to cancel the poles near to the imaginary axes. The approach is based on the root locus method. Application to Barka II power station connected to the main interconnected system of Oman is presented. The peak load at summer is considered as the system is near to instability. The Barka SMIB is modeled as a fourth order non-linear system. A linearized model is then obtained using MATLAB/Simulink. The simulation results validate the proposed design for the PSS.

The question of loyalty in autocratic regimes has drawn a sustained scholarly interest, especiall... more The question of loyalty in autocratic regimes has drawn a sustained scholarly interest, especially with the resilience of many of these regimes over most of world history and over the past few decades in particular. Autocratic leaders need to secure the support of their militaries to survive in office and to minimize the risk of a coup. Among the commonly employed mechanisms in this regard is the extension of extra-budgetary financial rewards, including ‘Military-Owned Businesses (MOBs).’ Nevertheless, under the increasingly significant threat of an uprising from below, military defection remains the key for the success of the revolution. The question then becomes: under what conditions would a military defect from an autocratic ruling alliance? Although many answers have been proposed to solve this puzzle, an increasing number of cases are proving them insufficient. Alternatively, this project presents one novel answer to this question, which is: militaries are “defection-proofed” ...

Arabian Journal for Science and Engineering, 2020

This manuscript introduces a new robust control design of car active suspension systems using ell... more This manuscript introduces a new robust control design of car active suspension systems using ellipsoidal techniques. The impact of road irregularities is regarded as an external disturbance. The suggested controller meets the following objectives: optimal passenger comfort, actuator control force limit satisfaction, effective disturbance rejection, and robustness against changes in passengers' load. The passenger load variations cause system uncertainty that is modeled as norm-bounded. A new sufficient condition is established based on the invariant ellipsoid method and the linear matrix inequalities optimization to guarantee robust stability and performance for the system. Time-domain model of road roughness based on trigonometric functions is studied. The performance of the proposed controller is tested using a quarter-car model with an active suspension system. Comparative simulation with other techniques, e.g., H ∞ and regional pole placement, is given. Actuator dynamics and system nonlinearities are modeled and included in the design at the end.

This study addresses the issue of photovoltaic (PV) systems optimal allocation in electric distri... more This study addresses the issue of photovoltaic (PV) systems optimal allocation in electric distribution network. A case study of using particle swarm optimization (PSO) and genetic algorithms (GA) is presented. The objective function of the problem is to minimize system losses while improving voltage profile. The study considers the network of Masirah Island, Oman, as a case study system. The study includes two stages. In the first stage, the test system is modeled and simulated using the MATLAB load flow toolbox. In the second stage, both PSO and GA optimization tools are used to find the optimal allocation of PV systems. Both algorithms resulted in similar values for both the objective function value and decision variables. Simulation results shows that technical real power losses represent 2.1% of the total load. However, the optimal allocation of PV systems at five buses can reduce losses by 50%.

World Journal of Social Science Research, 2021

The question of loyalty in autocratic regimes has drawn a sustained scholarly interest, especiall... more The question of loyalty in autocratic regimes has drawn a sustained scholarly interest, especially as autocratic leaders need to secure the support of their militaries to survive in office and to minimize the risk of a coup. Among the commonly employed mechanisms in this regard is the extension of extra-budgetary financial rewards, including “Military-Owned Businesses (MOBs)”. Nevertheless, under the increasingly significant threat of an uprising from below, military defection remains the key for the success of the revolution. The question then becomes: under what conditions would a military defect from an autocratic ruling alliance? This paper presents one novel answer to this question, which is: militaries are “defection-proofed” in the face of mass uprisings when they develop financial dependency on the regime. This hypothesis is tested comparatively against the cases of mass protests in China (1989), Indonesia (1998), Thailand (2006), and Iran (2009).

Saudi Medical Journal, Mar 1, 2007

To evaluate the prevalence of refluxing pelvic veins among female patients with lower extremity v... more To evaluate the prevalence of refluxing pelvic veins among female patients with lower extremity varicose veins and the role of embolization treatment in these cases. Of 158 female patients suffering from primary varicose veins of the lower extremities presented to the Venous Disease Clinic at Dhahran Health Center between January 2002 and December 2004, 25 patients (15.8%) were noted to have vulvar or postero-medial thigh varices or both. Those were referred for trans-jugular descending pelvic venography with or without subsequent embolization of the contributing refluxing veins. Venous reflux contributing to the vulvoperineal or posterior thigh varices was detected in 23 patients (92%) on catheter venography. Left ovarian venous reflux was responsible for 60% of all cases. Embolization, using multiple coils, was successful in 18 patients with positive reflux (78.3%). One patient had primary vulvar venous malformation that required additional percutaneous sclerotherapy using dehydrated ethanol. Four patients had femoro-saphenous reflux contributing to the varices and required subsequent surgical ligation excision. All treated cases showed significant improvement of their symptoms without any procedure related complications. In patients with vulvar or postero-medial thigh varicose veins, radiological study of ovarian and hypogastric venous reflux should be considered. Trans-jugular descending venography and embolization is a feasible, effective and safe diagnostic and therapeutic modality.

Electric Power Components and Systems, 2009

ABSTRACT This article presents the design technique of an adaptive power system stabilizer using ... more ABSTRACT This article presents the design technique of an adaptive power system stabilizer using adaptive neuro-fuzzy inference systems trained via data obtained from genetic algorithms. The parameters of a standard power system stabilizer are tuned using adaptive neuro-fuzzy inference systems to achieve a certain damping ratio and settling time at all load points within a wide region of operation. The overall transfer function of the system is derived in terms of the power system stabilizer parameters. A genetic algorithm is used to minimize a multi-objective optimization function that forces the damping ratio and settling time of the system to desired values. The optimization process is separately conducted at selected operating points to yield power system stabilizer parameters that change with load variations. Results of genetic algorithm optimization are used to form a training dataset of an adaptive neuro-fuzzy inference systems agent, which could give the power system stabilizer parameters at any load within the specified region of operation. Results of power system stabilizer testing show that the desired performance indices could be fulfilled from light load to over load under both lagging and leading power factor conditions. System performance shows a remarkable improvement of dynamic stability by obtaining a well-damped time response.

Computers & Electrical Engineering, 1984

This paper considers the problem of stabilizing the dynamics of a large electric power system, re... more This paper considers the problem of stabilizing the dynamics of a large electric power system, represented by a linear time invariant system of equations, by using several decentralized (or local) state feedback control laws. The stabilization problem is formulated into a functional minimization problem which implicitly controls the closed-loop eigenvalues of the controlled system. The constraint of decentralization is tackled in the minimization algorithm by using the method of feasible directions. To illustrate the application of the algorithm, it is used to stabilize a three machine electric power system.

Energies

This paper deals with a discrete-time stochastic control model design for random failure prone an... more This paper deals with a discrete-time stochastic control model design for random failure prone and maintenance in a single machine infinite bus (SMIB) system. This model includes the practical values of failure/repair rate of transmission lines and transformers. The probability matrix is, therefore, calculated accordingly. The model considers two extreme modes of operations: the most reliable mode and the least reliable contingency case. This allows the control design which stochastically stabilizes the system under jump Markov disturbances. For adequate transient response, the proposed state feedback power system stabilizer (PSS) achieves a desired settling time and damping ratio by placing the closed-loop poles in a desired region. The control target should also be satisfied for load variations in either mode of operation. A sufficient condition is developed to achieve the control objectives via solving a set of linear matrix inequalities (LMI). Using simulation, the performance o...

MEJ. Mansoura Engineering Journal, 2021

Particulate Science and Technology, 2018

A nominal calcium silicate was prepared through wet route and investigated as sorbent for the rem... more A nominal calcium silicate was prepared through wet route and investigated as sorbent for the removal of long-lived radionuclides 134 Cs and 152 þ 154 Eu from aqueous solutions. The physicochemical properties of the prepared nonmaterial such as FT-IR, SEM, XRD and TEM were examined. Sorption of both 134 Cs and 152 þ 154 Eu onto the nanomaterial from aqueous solutions was evaluated in a consignment technique with regard to the temperature, pH and contact time. The kinetics of adsorption of 134 Cs and 152 þ 154 Eu have been discussed using three kinetic models namely, pseudo-first-order, pseudo-second-order and Elovich models. The results designated that the second-order model could describe the sorption kinetics for the two metal ions. The present work launches a new trend of research by considering the nano-calcium silicate as an engineered barrier around the disposal facilities at the nuclear activity centers.

TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES, 2016

Steam valve control is usually discarded in power system stability due to belief in its slow resp... more Steam valve control is usually discarded in power system stability due to belief in its slow response. The present manuscript makes use of it as a backup control in the case of failure of the main fast excitation control. The model describing system dynamics as a function of the two controllers, with wide range loading conditions, is derived in a norm-bounded format. Linear matrix inequalities are derived as a sufficient condition to obtain reliable controllers that provide good oscillation damping when both controllers are sound or even in the case of failure of either one. The design scheme is robust in the sense that it keeps reliable stability against wide load changes as well. A single machine infinite bus system is presented to illustrate the proposed design procedure and exhibit its performance. Results of excitation and governor controller testing show that the desired performance could be fulfilled from light load to heavy load conditions. System performance shows a remarkable improvement of dynamic stability by obtaining a well-damped oscillation time response even in the case of failure of either controller. Extension of the proposed controller to multiarea load-frequency control with time delay is also presented.

International Journal of Electrical Power & Energy Systems, 2015

In this paper, a new saturated control design for uncertain power systems is proposed. The develo... more In this paper, a new saturated control design for uncertain power systems is proposed. The developed saturated control scheme is based on linear matrix inequality (LMI) optimization to achieve prescribed dynamic performance measures, e.g., settling time and damping ratio. In this design, the closed-loop poles are forced to lie within a desired region. The proposed design provides robustness against system uncertainties. The simulation results of both a single machine infinite bus and a multi-machine power systems are given to validate the effectiveness of the proposed controller.

IEEE Transactions on Smart Grid, 2014

We study the demand side management (DSM) problem when customers are equipped with energy storage... more We study the demand side management (DSM) problem when customers are equipped with energy storage devices. Two games are discussed: the first is a non-cooperative one played between the residential energy consumers, while the second is a Stackelberg game played between the utility provider and the energy consumers. We introduce a new cost function applicable to the case of users selling back stored energy. The non-cooperative energy consumption game is played between users who schedule their energy use to minimize energy cost. The game is shown to have a unique Nash equilibrium, that is also the global system optimal point. In the Stackelberg game, the utility provider sets the prices to maximize its profit knowing that users will respond by minimizing their cost. We provide existence and uniqueness results for the Stackelberg equilibrium. The Stackelberg game is shown to be the general case of the minimum Peak-to-Average power ratio (PAR) problem. Two algorithms, centralized and distributed, are presented to solve the Stackelberg game. We present results that elucidate the interplay between storage capacity, energy requirements, number of users and system performance measured in total cost and peak-to-average power ratio (PAR).