saeed abazari - Academia.edu (original) (raw)

Papers by saeed abazari

Research paper thumbnail of Modulation of Current Source Inverter

DOAJ (DOAJ: Directory of Open Access Journals), Apr 1, 2011

Research paper thumbnail of Direct torque and indirect flux control of brushless DC motor with non-sinusoidal back-EMF without position sensor

Iranian Conference on Electrical Engineering, May 17, 2011

In this paper, the position-sensorless direct torque and indirect flux control of brushless dc (B... more In this paper, the position-sensorless direct torque and indirect flux control of brushless dc (BLDC) motor with nonsinusoidal back electromotive force (EMF) has been extensively investigated. In the literature, several methods have been proposed for BLDC motor drives to obtain optimum current and torque control with minimum torque pulsations. Most methods are complicated and do not consider the stator flux linkage control, therefore, possible high-speed operations are not feasible. In this study, a novel and simple approach to achieve a low-frequency torque ripple-free direct torque control (DTC) with maximum efficiency based on dq reference frame is presented. The proposed sensorless method closely resembles the conventional DTC scheme used for sinusoidal ac motors such that it controls the torque directly and stator flux amplitude indirectly using d-axis current. This method does not require pulsewidth modulation and proportional plus integral regulators and also permits the regulation of varying signals. Furthermore, to eliminate the low-frequency torque oscillations, two actual and easily available line-to-line back EMF constants (k ba and k ca) according to electrical rotor position are obtained offline and converted to the dq frame equivalents using the new line-to-line park transformation. Then, they are set up in the look-up table for torque estimation. The validity and practical applications of the proposed sensorless three-phase conduction DTC of BLDC motor drive scheme are verified through simulations and experimental results. Index Terms-Brushless dc (BLDC) motor, direct torque control (DTC), fast torque response, low-frequency torque ripples, nonsinusoidal back electromotive force (EMF), position-sensorless control, stator flux control, torque pulsation. I. INTRODUCTION T HE permanent-magnet synchronous motor (PMSM) and brushless dc (BLDC) motor drives are used extensively in several high-performance applications, ranging from servos to traction drives, due to several distinct advantages such as high power density, high efficiency, large torque to inertia ratio, and simplicity in their control [1]-[3]. In many applications, obtaining a low-frequency ripple-free torque and instantaneous torque and even flux control are of primary concern for BLDC motors with nonsinusoidal back

Research paper thumbnail of Optimal Choice and Allocation of FACTS Devices to Decrease Power Network Loss's Using Genetic Algorithms

Majlesi Journal of Electrical Engineering, Mar 1, 2009

Page 1. ﻞﺼﻓ ﻲﻤﻠﻋ ﻪﻣﺎﻧ – ﻲﺸﻫوﮋﭘ ﻲﺴﻠﺠﻣ قﺮﺑ ﻲﺳﺪﻨﻬﻣ لﺎﺳ مﻮﺳ / هرﺎﻤﺷ لوا / رﺎﻬﺑ 1388 45 و بﺎﺨﺘﻧا تاودا... more Page 1. ﻞﺼﻓ ﻲﻤﻠﻋ ﻪﻣﺎﻧ – ﻲﺸﻫوﮋﭘ ﻲﺴﻠﺠﻣ قﺮﺑ ﻲﺳﺪﻨﻬﻣ لﺎﺳ مﻮﺳ / هرﺎﻤﺷ لوا / رﺎﻬﺑ 1388 45 و بﺎﺨﺘﻧا تاودا ﻪﻨﻴﻬﺑ ﻲﺑﺎﻳﺎﺟ FACTS ﻪﺑ ترﺪﻗ ﻪﻜﺒﺷ تﺎﻔﻠﺗ ﺶﻫﺎﻛرﻮﻈﻨﻣ ﻪﺑ ﻚﻴﺘﻧژ ﻢﺘﻳرﻮﮕﻟا ﻚﻤﻛ يرذﺎﺑا ﺪﻴﻌﺳ 1 ، نﺎﻴﻠﻘﻫﺎﺷ ﺮﻔﻨﻀﻏ 2 ، ﻲﺘﻋﺎﻨﻗ ﺪﻴﻣا 3 1-،رﺎﻳدﺎﺘﺳا دﺮﻛﺮﻬﺷ هﺎﮕﺸﻧاد ، com. yahoo @ saeedabazari ...

Research paper thumbnail of Computer Games and Violence

Research paper thumbnail of Dynamic stability improvement of power system with DFIG using multi-input backstepping control

Electrical Engineering, Sep 7, 2022

The paper investigates the application of Static Synchronous Compensator (STATCOM) with synchronv... more The paper investigates the application of Static Synchronous Compensator (STATCOM) with synchronverter control to enhance dynamic stability. Synchronverter is a control strategy for voltage source converters that emulates a synchronous generator, therefore providing virtual inertia. A thorough analysis of system stability with STATCOM controlled using synchronverter is presented. Furthermore, a comparison to vector control is provided. The analysis was conducted for a commonly known Single Machine Infinite Bus (SMIB) test case. The authors also compare the synchronverter and vector control performance using different mathematical tools such as eigenvalue analysis, numerical simulation, and lyapunov theory. Synchronverter algorithm improves the damping of the system, as small-signal analysis shows. The results of numerical simulations demonstrate the improvement of dynamic stability. Besides, the stability region also improves in the case of synchronverter. Finally, the paper demonstrates on the IEEE 39 bus system that the operation of STATCOM with a synchronverter control strategy is feasible and improves dynamic stability. Synchronverter brings the advantages of artificially adding inertia to the system, an essential issue in modern power systems.

Research paper thumbnail of Optimal Load Shedding in Deregulated System and Consideration of Effective Factors by Using a Predictor-Corrector Interior-Point Method (IPM)

DOAJ (DOAJ: Directory of Open Access Journals), Jul 1, 2010

Research paper thumbnail of Discourse analysis of texts on Iraq-Iran War: A case study of Persian to English narrations

Forum for Linguistic Studies

While critical discourse analysis has gained solid ground in war literature and narratives, few s... more While critical discourse analysis has gained solid ground in war literature and narratives, few studies have used this analytical tool to scrutinize the translation of ideology in the literature relating to war. This study aimed to analyze how ideology was (re)produced and translated in the Iraq-Iran War narrations. To this end, a sample from a corpus of such narrations was selected and analyzed based on Farahzad’s (2012) CDA model. The results showed that ideologies produced in the proto-texts were rendered in the meta-texts with a few alterations at the textual level and with no change at the semiotic level. The findings indicated the role of ideology in shaping the translated text and revealed how language can be manipulated as a social practice to support ideologies, maintain power, and serve the interests of powerful groups in society. Such materials could also shape the reader’s mind about war. Parallel studies would shed more light on the function of ideology in war literatur...

Research paper thumbnail of Design of Wide Area SVC Robust Controller for Damping Inter-Area Oscillations of a Ppower System

Research paper thumbnail of Transient stability constrained optimal power flow using independent dynamic simulation

IET Generation, Transmission & Distribution, 2013

This paper proposes a new approach able to maximize the interface flow limits in power systems an... more This paper proposes a new approach able to maximize the interface flow limits in power systems and to find a new operating state that is secure with respect to both, dynamic (transient stability) and static security constraints. It combines the Maximum Allowable Transfer (MAT) method, recently developed for the simultaneous control of a set of contingencies, and an Optimal Power Flow (OPF) method for maximizing the interface power flow. The approach and its performances are illustrated by means of simulations carried out on a real world power system.

Research paper thumbnail of Transient Stability Improvement by Using Advanced Static VAR Compensators

Electric Power Components and Systems, 2003

... 321 Page 2. 322 S. Abazari et al. of a power system to maintain the electric machines synchro... more ... 321 Page 2. 322 S. Abazari et al. of a power system to maintain the electric machines synchronized when there is a severe disturbance in the system. Response of the system to a severe disturbance involves large excursions of the rotor angles of the generators. ...

Research paper thumbnail of A Rule-Based Advanced Static Var Compensator Control Scheme for Transient Stability Improvement

Scientia Iranica

The paper presents the application of a rule-based control scheme for an Advanced Static Var Comp... more The paper presents the application of a rule-based control scheme for an Advanced Static Var Compensator (ASVC) to improve power system transient stability. The proposed method uses a current reference, based on the Transient Energy Function (TEF) approach. The proposed scheme provides, also, a continuous control of the reactive power ow. The performance of the proposed approach is compared with that of a system using a conventional control method and of a system without ASVC. A single-machine system and an IEEE three machine system are used to verify the performance of the proposed method.

Research paper thumbnail of A robust transient energy function‐based controller for enhancing transient stability of virtual power system

IET Generation, Transmission & Distribution

This paper offers non‐linear control for enhancing the transient stability in power systems conta... more This paper offers non‐linear control for enhancing the transient stability in power systems containing a photovoltaic (PV) and doubly fed induction generator (DFIG) by transient energy function (TEF) method and finite‐time observers. At first, the TEF method is utilized to enhance the transient stability in a power system containing a PV, DFIG, and synchronous generator (SG) by constructing a hybrid Lyapunov function. Then, the derivative terms in control are estimated with finite‐time observers. The main contribution of the research is the application of the TEF technique in the transient stability evaluation of a power system consisting of PV, SG, and DFIG. Another innovation of the research is the simultaneous control of DFIG and PV, whose uncertain parameters are estimated with the use of finite‐time observer. The proposed non‐linear control scheme is robust against changes in the configuration of the power system. In order to show the capability of this control scheme, time dom...

Research paper thumbnail of A Novel Control to Improve Dynamic Stability of Power Systems Including DFIG and SSSC

DOAJ (DOAJ: Directory of Open Access Journals), Dec 1, 2022

This study is concerned with the design of multi-input Dynamic Surface Control (DSC) to dynamic s... more This study is concerned with the design of multi-input Dynamic Surface Control (DSC) to dynamic stability improvement of power systems which include both Doubly Feed Induction Generator (DFIG) and Static Synchronous Series Compensator (SSSC). The presented control method has a multi-input feature which acts on synchronous generators. To improve dynamic stability, the control law is developed by applying a suitable Lyapunov function. The coefficients of the proposed controller are determined by use of metaheuristic optimization algorithms. This optimal control law leads to a significantly improved performance in comparison with linear control. A particular low-pass filter is also introduced and applied to cancel the effects of additional undesired terms in the design method, leading to a simplified control form compared to the other available approaches in the literature. Implementing an adaptive parameter estimation scheme will result in the robustness of the proposed method. The effectiveness of the presented approach is investigated on a standard 39-Bus power system which includes DFIG and SSSC.

Research paper thumbnail of Improving the Mitigation of Voltage Flicker by Usage of Fuzzy Control in a Distribution Static Synchronous Compensator (DSTATCOM)

This paper presents a study about of a fuzzy Controlled STATCOM, which can be applied for mitiga... more This paper presents a study about of a fuzzy Controlled STATCOM, which can be applied for mitigation of the voltage flicker in a distribution system. The voltage flicker is produced by a large variable load absorbing continuously changing currents such as an arc furnace. The DSTATCOM includes a voltage-sourced PWM inverter and its control system. The control strategy of the DSTATCOM plays an important role in maintaining the voltage flicker. Here, the DSTATCOM controller is designed with two types of controllers, linear proportional-integral (PI) and nonlinear fuzzy logic. The simulation of the DSTATCOM with 3MVar reactive power on a 25 KV distribution network is carried out in MATLAB/SIMULINK software. Finaly, fuzzy controllers were evaluated by comparing its performance with the PI controllers. It is observed that the fuzzy controllers are very superior in mitigating the voltage flicker.

Research paper thumbnail of Direct Torque and Indirect Flux Control of Brushless DC Motor

IEEE/ASME Transactions on Mechatronics, 2011

In this paper, the position-sensorless direct torque and indirect flux control of brushless dc (B... more In this paper, the position-sensorless direct torque and indirect flux control of brushless dc (BLDC) motor with nonsinusoidal back electromotive force (EMF) has been extensively investigated. In the literature, several methods have been proposed for BLDC motor drives to obtain optimum current and torque control with minimum torque pulsations. Most methods are complicated and do not consider the stator flux linkage control, therefore, possible high-speed operations are not feasible. In this study, a novel and simple approach to achieve a low-frequency torque ripple-free direct torque control (DTC) with maximum efficiency based on dq reference frame is presented. The proposed sensorless method closely resembles the conventional DTC scheme used for sinusoidal ac motors such that it controls the torque directly and stator flux amplitude indirectly using d-axis current. This method does not require pulsewidth modulation and proportional plus integral regulators and also permits the regulation of varying signals. Furthermore, to eliminate the low-frequency torque oscillations, two actual and easily available line-to-line back EMF constants (k ba and k ca) according to electrical rotor position are obtained offline and converted to the dq frame equivalents using the new line-to-line park transformation. Then, they are set up in the look-up table for torque estimation. The validity and practical applications of the proposed sensorless three-phase conduction DTC of BLDC motor drive scheme are verified through simulations and experimental results. Index Terms-Brushless dc (BLDC) motor, direct torque control (DTC), fast torque response, low-frequency torque ripples, nonsinusoidal back electromotive force (EMF), position-sensorless control, stator flux control, torque pulsation. I. INTRODUCTION T HE permanent-magnet synchronous motor (PMSM) and brushless dc (BLDC) motor drives are used extensively in several high-performance applications, ranging from servos to traction drives, due to several distinct advantages such as high power density, high efficiency, large torque to inertia ratio, and simplicity in their control [1]-[3]. In many applications, obtaining a low-frequency ripple-free torque and instantaneous torque and even flux control are of primary concern for BLDC motors with nonsinusoidal back

Research paper thumbnail of Transient stability increase of multi-machine power system by using SSSC and DFIG control with TEF technique and super twisting differentiator

Research paper thumbnail of Novel non‐linear control of DFIG and UPFC for transient stability increment of power system

IET Generation, Transmission & Distribution

Research paper thumbnail of ‫مجله‬ ،‫تبريز‬ ‫دانشگاه‬ ‫برق‬ ‫مهندسي‬ ‫جلد‬ 54 ، ‫شماره‬ 2 ‫پياپي‬ ‫شماره‬ 22 ‫سيستم‬ ‫در‬ ‫فازی‬ ‫کنترل‬ ‫روش‬ ‫به‬ ‫ديناميکي‬ ‫پايداری‬ ‫بهبود‬ ‫قدرت‬ ‫های‬ ‫چند‬ ‫کاربرد‬ ‫با‬ ‫ماشينه‬ TCSC ‫اباذری‬ ‫سعيد‬ Improvement of Dynamic Stability of Multi-Machine Power Systems using TCSC and Fuzzy ...

When an error occurs in a power system, stability and damping of fluctuations is an important fac... more When an error occurs in a power system, stability and damping of fluctuations is an important factor on which needs to pay attention during the system design. The use of the Power System Stabilizer (PSS) can damp the fluctuations due to small disturbances. Also Flexible AC transmission Systems (FACTS) in a power system, can be effective in improvement of the dynamic stability and in damping of low-frequency fluctuations. One of the FACTS elements is TCSC that can help rapid damping of the oscillation by changing the reactance of the line. In this paper, a TCSC with properly designed fuzzy controller is used to improve the dynamic stability. The proposed method does not need to set the parameters and the on-line controller can help damping of the fluctuations. Simulation results show that the fuzzy based TCSC controller can damp the fluctuations effectively in a power system connected to a single machine infinite bus (SMIB) and also in a multi-machine system (9 BUS IEEE).

Research paper thumbnail of Controllers for Transient Stability Improvement

This paper presents the comparative performance of neuro-Fuzzy controlled Voltage Source Converte... more This paper presents the comparative performance of neuro-Fuzzy controlled Voltage Source Converters (VSC) based Flexible AC Transmission System (FACTS) devices, such as Static Synchronous Series Compensator (SSSC), Static Synchronous Compensator (STATCOM), and Unified Power Flow Controller (UPFC) in terms of improvement in transient stability. In neuro-fuzzy control method the simplicity of fuzzy systems and the ability of training in neural networks have been combined. The training data set the parameters of membership functions in fuzzy controller. This Adaptive Network Fuzzy Inference System (ANFIS) can track the given input-output data in order to conform to the desired controller. The maximization of energy function of UPFC is used as an objective function to generate the training data. Proposed method is tested on a single machine infinitive bus system to confirm its performance through simulation. The results prove the noticeable influence of ANFIS controlled UPFC on increasing Critical Clearing Time (CCT) of system.

Research paper thumbnail of A New Fuzzy-Neural Statcom Controller for Transient Stability Improvement in Power Systems

In this paper a neuro-fuzzy controller is proposed to enhance transient stability and increase cr... more In this paper a neuro-fuzzy controller is proposed to enhance transient stability and increase critical clearing time (CCT) in the static synchronous compensator (STATCOM). For achieving this idea, first the controller is designed based on the Lyapunov energy function. In order to avoid complexity of computation and overcome system uncertainty a neuro-fuzzy controller is proposed. In this controller, neural network determines the system rules and membership functions. In order to design a neural network and its training patterns, the energy function controller is used under various system conditions. This controller has learning abilities due to its robust fuzzy controller and neural network. Simulation results on the single-machine infinite-bus (SMIB) show that the neuro-fuzzy controller damps electromechanical oscillations and increases the critical clearing time.

Research paper thumbnail of Modulation of Current Source Inverter

DOAJ (DOAJ: Directory of Open Access Journals), Apr 1, 2011

Research paper thumbnail of Direct torque and indirect flux control of brushless DC motor with non-sinusoidal back-EMF without position sensor

Iranian Conference on Electrical Engineering, May 17, 2011

In this paper, the position-sensorless direct torque and indirect flux control of brushless dc (B... more In this paper, the position-sensorless direct torque and indirect flux control of brushless dc (BLDC) motor with nonsinusoidal back electromotive force (EMF) has been extensively investigated. In the literature, several methods have been proposed for BLDC motor drives to obtain optimum current and torque control with minimum torque pulsations. Most methods are complicated and do not consider the stator flux linkage control, therefore, possible high-speed operations are not feasible. In this study, a novel and simple approach to achieve a low-frequency torque ripple-free direct torque control (DTC) with maximum efficiency based on dq reference frame is presented. The proposed sensorless method closely resembles the conventional DTC scheme used for sinusoidal ac motors such that it controls the torque directly and stator flux amplitude indirectly using d-axis current. This method does not require pulsewidth modulation and proportional plus integral regulators and also permits the regulation of varying signals. Furthermore, to eliminate the low-frequency torque oscillations, two actual and easily available line-to-line back EMF constants (k ba and k ca) according to electrical rotor position are obtained offline and converted to the dq frame equivalents using the new line-to-line park transformation. Then, they are set up in the look-up table for torque estimation. The validity and practical applications of the proposed sensorless three-phase conduction DTC of BLDC motor drive scheme are verified through simulations and experimental results. Index Terms-Brushless dc (BLDC) motor, direct torque control (DTC), fast torque response, low-frequency torque ripples, nonsinusoidal back electromotive force (EMF), position-sensorless control, stator flux control, torque pulsation. I. INTRODUCTION T HE permanent-magnet synchronous motor (PMSM) and brushless dc (BLDC) motor drives are used extensively in several high-performance applications, ranging from servos to traction drives, due to several distinct advantages such as high power density, high efficiency, large torque to inertia ratio, and simplicity in their control [1]-[3]. In many applications, obtaining a low-frequency ripple-free torque and instantaneous torque and even flux control are of primary concern for BLDC motors with nonsinusoidal back

Research paper thumbnail of Optimal Choice and Allocation of FACTS Devices to Decrease Power Network Loss's Using Genetic Algorithms

Majlesi Journal of Electrical Engineering, Mar 1, 2009

Page 1. ﻞﺼﻓ ﻲﻤﻠﻋ ﻪﻣﺎﻧ – ﻲﺸﻫوﮋﭘ ﻲﺴﻠﺠﻣ قﺮﺑ ﻲﺳﺪﻨﻬﻣ لﺎﺳ مﻮﺳ / هرﺎﻤﺷ لوا / رﺎﻬﺑ 1388 45 و بﺎﺨﺘﻧا تاودا... more Page 1. ﻞﺼﻓ ﻲﻤﻠﻋ ﻪﻣﺎﻧ – ﻲﺸﻫوﮋﭘ ﻲﺴﻠﺠﻣ قﺮﺑ ﻲﺳﺪﻨﻬﻣ لﺎﺳ مﻮﺳ / هرﺎﻤﺷ لوا / رﺎﻬﺑ 1388 45 و بﺎﺨﺘﻧا تاودا ﻪﻨﻴﻬﺑ ﻲﺑﺎﻳﺎﺟ FACTS ﻪﺑ ترﺪﻗ ﻪﻜﺒﺷ تﺎﻔﻠﺗ ﺶﻫﺎﻛرﻮﻈﻨﻣ ﻪﺑ ﻚﻴﺘﻧژ ﻢﺘﻳرﻮﮕﻟا ﻚﻤﻛ يرذﺎﺑا ﺪﻴﻌﺳ 1 ، نﺎﻴﻠﻘﻫﺎﺷ ﺮﻔﻨﻀﻏ 2 ، ﻲﺘﻋﺎﻨﻗ ﺪﻴﻣا 3 1-،رﺎﻳدﺎﺘﺳا دﺮﻛﺮﻬﺷ هﺎﮕﺸﻧاد ، com. yahoo @ saeedabazari ...

Research paper thumbnail of Computer Games and Violence

Research paper thumbnail of Dynamic stability improvement of power system with DFIG using multi-input backstepping control

Electrical Engineering, Sep 7, 2022

The paper investigates the application of Static Synchronous Compensator (STATCOM) with synchronv... more The paper investigates the application of Static Synchronous Compensator (STATCOM) with synchronverter control to enhance dynamic stability. Synchronverter is a control strategy for voltage source converters that emulates a synchronous generator, therefore providing virtual inertia. A thorough analysis of system stability with STATCOM controlled using synchronverter is presented. Furthermore, a comparison to vector control is provided. The analysis was conducted for a commonly known Single Machine Infinite Bus (SMIB) test case. The authors also compare the synchronverter and vector control performance using different mathematical tools such as eigenvalue analysis, numerical simulation, and lyapunov theory. Synchronverter algorithm improves the damping of the system, as small-signal analysis shows. The results of numerical simulations demonstrate the improvement of dynamic stability. Besides, the stability region also improves in the case of synchronverter. Finally, the paper demonstrates on the IEEE 39 bus system that the operation of STATCOM with a synchronverter control strategy is feasible and improves dynamic stability. Synchronverter brings the advantages of artificially adding inertia to the system, an essential issue in modern power systems.

Research paper thumbnail of Optimal Load Shedding in Deregulated System and Consideration of Effective Factors by Using a Predictor-Corrector Interior-Point Method (IPM)

DOAJ (DOAJ: Directory of Open Access Journals), Jul 1, 2010

Research paper thumbnail of Discourse analysis of texts on Iraq-Iran War: A case study of Persian to English narrations

Forum for Linguistic Studies

While critical discourse analysis has gained solid ground in war literature and narratives, few s... more While critical discourse analysis has gained solid ground in war literature and narratives, few studies have used this analytical tool to scrutinize the translation of ideology in the literature relating to war. This study aimed to analyze how ideology was (re)produced and translated in the Iraq-Iran War narrations. To this end, a sample from a corpus of such narrations was selected and analyzed based on Farahzad’s (2012) CDA model. The results showed that ideologies produced in the proto-texts were rendered in the meta-texts with a few alterations at the textual level and with no change at the semiotic level. The findings indicated the role of ideology in shaping the translated text and revealed how language can be manipulated as a social practice to support ideologies, maintain power, and serve the interests of powerful groups in society. Such materials could also shape the reader’s mind about war. Parallel studies would shed more light on the function of ideology in war literatur...

Research paper thumbnail of Design of Wide Area SVC Robust Controller for Damping Inter-Area Oscillations of a Ppower System

Research paper thumbnail of Transient stability constrained optimal power flow using independent dynamic simulation

IET Generation, Transmission & Distribution, 2013

This paper proposes a new approach able to maximize the interface flow limits in power systems an... more This paper proposes a new approach able to maximize the interface flow limits in power systems and to find a new operating state that is secure with respect to both, dynamic (transient stability) and static security constraints. It combines the Maximum Allowable Transfer (MAT) method, recently developed for the simultaneous control of a set of contingencies, and an Optimal Power Flow (OPF) method for maximizing the interface power flow. The approach and its performances are illustrated by means of simulations carried out on a real world power system.

Research paper thumbnail of Transient Stability Improvement by Using Advanced Static VAR Compensators

Electric Power Components and Systems, 2003

... 321 Page 2. 322 S. Abazari et al. of a power system to maintain the electric machines synchro... more ... 321 Page 2. 322 S. Abazari et al. of a power system to maintain the electric machines synchronized when there is a severe disturbance in the system. Response of the system to a severe disturbance involves large excursions of the rotor angles of the generators. ...

Research paper thumbnail of A Rule-Based Advanced Static Var Compensator Control Scheme for Transient Stability Improvement

Scientia Iranica

The paper presents the application of a rule-based control scheme for an Advanced Static Var Comp... more The paper presents the application of a rule-based control scheme for an Advanced Static Var Compensator (ASVC) to improve power system transient stability. The proposed method uses a current reference, based on the Transient Energy Function (TEF) approach. The proposed scheme provides, also, a continuous control of the reactive power ow. The performance of the proposed approach is compared with that of a system using a conventional control method and of a system without ASVC. A single-machine system and an IEEE three machine system are used to verify the performance of the proposed method.

Research paper thumbnail of A robust transient energy function‐based controller for enhancing transient stability of virtual power system

IET Generation, Transmission & Distribution

This paper offers non‐linear control for enhancing the transient stability in power systems conta... more This paper offers non‐linear control for enhancing the transient stability in power systems containing a photovoltaic (PV) and doubly fed induction generator (DFIG) by transient energy function (TEF) method and finite‐time observers. At first, the TEF method is utilized to enhance the transient stability in a power system containing a PV, DFIG, and synchronous generator (SG) by constructing a hybrid Lyapunov function. Then, the derivative terms in control are estimated with finite‐time observers. The main contribution of the research is the application of the TEF technique in the transient stability evaluation of a power system consisting of PV, SG, and DFIG. Another innovation of the research is the simultaneous control of DFIG and PV, whose uncertain parameters are estimated with the use of finite‐time observer. The proposed non‐linear control scheme is robust against changes in the configuration of the power system. In order to show the capability of this control scheme, time dom...

Research paper thumbnail of A Novel Control to Improve Dynamic Stability of Power Systems Including DFIG and SSSC

DOAJ (DOAJ: Directory of Open Access Journals), Dec 1, 2022

This study is concerned with the design of multi-input Dynamic Surface Control (DSC) to dynamic s... more This study is concerned with the design of multi-input Dynamic Surface Control (DSC) to dynamic stability improvement of power systems which include both Doubly Feed Induction Generator (DFIG) and Static Synchronous Series Compensator (SSSC). The presented control method has a multi-input feature which acts on synchronous generators. To improve dynamic stability, the control law is developed by applying a suitable Lyapunov function. The coefficients of the proposed controller are determined by use of metaheuristic optimization algorithms. This optimal control law leads to a significantly improved performance in comparison with linear control. A particular low-pass filter is also introduced and applied to cancel the effects of additional undesired terms in the design method, leading to a simplified control form compared to the other available approaches in the literature. Implementing an adaptive parameter estimation scheme will result in the robustness of the proposed method. The effectiveness of the presented approach is investigated on a standard 39-Bus power system which includes DFIG and SSSC.

Research paper thumbnail of Improving the Mitigation of Voltage Flicker by Usage of Fuzzy Control in a Distribution Static Synchronous Compensator (DSTATCOM)

This paper presents a study about of a fuzzy Controlled STATCOM, which can be applied for mitiga... more This paper presents a study about of a fuzzy Controlled STATCOM, which can be applied for mitigation of the voltage flicker in a distribution system. The voltage flicker is produced by a large variable load absorbing continuously changing currents such as an arc furnace. The DSTATCOM includes a voltage-sourced PWM inverter and its control system. The control strategy of the DSTATCOM plays an important role in maintaining the voltage flicker. Here, the DSTATCOM controller is designed with two types of controllers, linear proportional-integral (PI) and nonlinear fuzzy logic. The simulation of the DSTATCOM with 3MVar reactive power on a 25 KV distribution network is carried out in MATLAB/SIMULINK software. Finaly, fuzzy controllers were evaluated by comparing its performance with the PI controllers. It is observed that the fuzzy controllers are very superior in mitigating the voltage flicker.

Research paper thumbnail of Direct Torque and Indirect Flux Control of Brushless DC Motor

IEEE/ASME Transactions on Mechatronics, 2011

In this paper, the position-sensorless direct torque and indirect flux control of brushless dc (B... more In this paper, the position-sensorless direct torque and indirect flux control of brushless dc (BLDC) motor with nonsinusoidal back electromotive force (EMF) has been extensively investigated. In the literature, several methods have been proposed for BLDC motor drives to obtain optimum current and torque control with minimum torque pulsations. Most methods are complicated and do not consider the stator flux linkage control, therefore, possible high-speed operations are not feasible. In this study, a novel and simple approach to achieve a low-frequency torque ripple-free direct torque control (DTC) with maximum efficiency based on dq reference frame is presented. The proposed sensorless method closely resembles the conventional DTC scheme used for sinusoidal ac motors such that it controls the torque directly and stator flux amplitude indirectly using d-axis current. This method does not require pulsewidth modulation and proportional plus integral regulators and also permits the regulation of varying signals. Furthermore, to eliminate the low-frequency torque oscillations, two actual and easily available line-to-line back EMF constants (k ba and k ca) according to electrical rotor position are obtained offline and converted to the dq frame equivalents using the new line-to-line park transformation. Then, they are set up in the look-up table for torque estimation. The validity and practical applications of the proposed sensorless three-phase conduction DTC of BLDC motor drive scheme are verified through simulations and experimental results. Index Terms-Brushless dc (BLDC) motor, direct torque control (DTC), fast torque response, low-frequency torque ripples, nonsinusoidal back electromotive force (EMF), position-sensorless control, stator flux control, torque pulsation. I. INTRODUCTION T HE permanent-magnet synchronous motor (PMSM) and brushless dc (BLDC) motor drives are used extensively in several high-performance applications, ranging from servos to traction drives, due to several distinct advantages such as high power density, high efficiency, large torque to inertia ratio, and simplicity in their control [1]-[3]. In many applications, obtaining a low-frequency ripple-free torque and instantaneous torque and even flux control are of primary concern for BLDC motors with nonsinusoidal back

Research paper thumbnail of Transient stability increase of multi-machine power system by using SSSC and DFIG control with TEF technique and super twisting differentiator

Research paper thumbnail of Novel non‐linear control of DFIG and UPFC for transient stability increment of power system

IET Generation, Transmission & Distribution

Research paper thumbnail of ‫مجله‬ ،‫تبريز‬ ‫دانشگاه‬ ‫برق‬ ‫مهندسي‬ ‫جلد‬ 54 ، ‫شماره‬ 2 ‫پياپي‬ ‫شماره‬ 22 ‫سيستم‬ ‫در‬ ‫فازی‬ ‫کنترل‬ ‫روش‬ ‫به‬ ‫ديناميکي‬ ‫پايداری‬ ‫بهبود‬ ‫قدرت‬ ‫های‬ ‫چند‬ ‫کاربرد‬ ‫با‬ ‫ماشينه‬ TCSC ‫اباذری‬ ‫سعيد‬ Improvement of Dynamic Stability of Multi-Machine Power Systems using TCSC and Fuzzy ...

When an error occurs in a power system, stability and damping of fluctuations is an important fac... more When an error occurs in a power system, stability and damping of fluctuations is an important factor on which needs to pay attention during the system design. The use of the Power System Stabilizer (PSS) can damp the fluctuations due to small disturbances. Also Flexible AC transmission Systems (FACTS) in a power system, can be effective in improvement of the dynamic stability and in damping of low-frequency fluctuations. One of the FACTS elements is TCSC that can help rapid damping of the oscillation by changing the reactance of the line. In this paper, a TCSC with properly designed fuzzy controller is used to improve the dynamic stability. The proposed method does not need to set the parameters and the on-line controller can help damping of the fluctuations. Simulation results show that the fuzzy based TCSC controller can damp the fluctuations effectively in a power system connected to a single machine infinite bus (SMIB) and also in a multi-machine system (9 BUS IEEE).

Research paper thumbnail of Controllers for Transient Stability Improvement

This paper presents the comparative performance of neuro-Fuzzy controlled Voltage Source Converte... more This paper presents the comparative performance of neuro-Fuzzy controlled Voltage Source Converters (VSC) based Flexible AC Transmission System (FACTS) devices, such as Static Synchronous Series Compensator (SSSC), Static Synchronous Compensator (STATCOM), and Unified Power Flow Controller (UPFC) in terms of improvement in transient stability. In neuro-fuzzy control method the simplicity of fuzzy systems and the ability of training in neural networks have been combined. The training data set the parameters of membership functions in fuzzy controller. This Adaptive Network Fuzzy Inference System (ANFIS) can track the given input-output data in order to conform to the desired controller. The maximization of energy function of UPFC is used as an objective function to generate the training data. Proposed method is tested on a single machine infinitive bus system to confirm its performance through simulation. The results prove the noticeable influence of ANFIS controlled UPFC on increasing Critical Clearing Time (CCT) of system.

Research paper thumbnail of A New Fuzzy-Neural Statcom Controller for Transient Stability Improvement in Power Systems

In this paper a neuro-fuzzy controller is proposed to enhance transient stability and increase cr... more In this paper a neuro-fuzzy controller is proposed to enhance transient stability and increase critical clearing time (CCT) in the static synchronous compensator (STATCOM). For achieving this idea, first the controller is designed based on the Lyapunov energy function. In order to avoid complexity of computation and overcome system uncertainty a neuro-fuzzy controller is proposed. In this controller, neural network determines the system rules and membership functions. In order to design a neural network and its training patterns, the energy function controller is used under various system conditions. This controller has learning abilities due to its robust fuzzy controller and neural network. Simulation results on the single-machine infinite-bus (SMIB) show that the neuro-fuzzy controller damps electromechanical oscillations and increases the critical clearing time.