ABSTRACT: This paper presents the automatic design method for a thyristor-controlled phase shifter (TCPS) controller based on quantitative feedback theory (QFT) to improve power system stability in spite of system uncertainties and various disturbances. A genetic algorithm (GA) in a loop shaping state of QFT design has been used to design the TCPS controller satisfying all QFT bounds without repetition of a manual try and error. The proposed performance index in GA has been composed of the QFT bounds and the damping ratio. To verify control performance of the proposed TCPS controller based on QFT using GA, the closed loop eigenvalue and the damping of power system have been analyzed and nonlinear simulations for a single machine infinite bus system have been performed under various disturbances for various operating conditions. The control characteristics of the proposed TCPS controller have been compared with that of the conventional power system stabilizer (PSS) and conventional TCPC controller. The simulation results show that the proposed TCPS controller provided better dynamic responses in comparison with the conventional PSS and TCPS controller.
This document describes a control strategy for a PWM voltage source converter (PWM-VSC) using fuzzy logic to provide variable DC voltage for controlling the speed of a DC motor. A fuzzy logic controller is proposed to minimize errors in the DC voltage and stabilize it by regulating the amplitude of the network current. Simulation results show the fuzzy logic controller produces a stable DC voltage without overshoot to drive the DC motor, with less than 5% total harmonic distortion in the network current and a power factor near unity. The DC motor speed is also stable without overshoot in response to variations in the controlled DC voltage.
Multi-Machine Stability Using Dynamic Inversion Technique IJECEIAES
Stability studies of multi machine system are a major concern to power system engineers due to the increasing complexity involved. This paper deals with the application of a nonlinear technique called Dynamic Inversion, to TCSC for the improvement of stability of multi-machine system. The transient stability studies for various cases: without any controller, with 75% line compensation and with Dynamic Inversion technique, are compared. The critical clearing time as well as the maximum loading ability is also discussed. The result for the nonlinear controller is found to be better than all the other cases.
Constant Frequency Torque Controller for DTC with Multilevel Inverter of Indu...IJPEDS-IAES
Direct Torque Control using multilevel inverter (DTC-MLI) with hysteresis
controller suffers from high torque and flux ripple and variable switching
frequency. In this paper, a constant frequency torque controller is proposed to
enhance the DTC-MLI performance. The operational concepts of the
constant switching frequency torque controller of a DTC-MLI system
followed by the simulation results and analysis are presented. The proposed
system significantly improves the DTC drive in terms of dynamic
performance, smaller torque and flux ripple, and retains a constant switching
frequency.
PID Controller Response to Set-Point Change in DC-DC Converter ControlIAES-IJPEDS
Power converter operations and efficiency is affected by variation in supply
voltage, loads current, circuit elements, ageing and temperature. To meet the
objective of tight voltage regulation, power converters circuit module and the
control unit must be robust to reject disturbances arising from supply, load
variation and changes in circuit elements. PID controller has been the most
widely used in power converter control. This paper presents studies of
robustness of PID controller tuning methods to step changes in the set point
and disturbance rejection in power converter control. A DC-DC boost
converter was modelled using averaged state-space mothod and PID
controllers were designed with five different tuning methods. The study
reveals the transient response and disturbance rejection capability of each
tuning methods for their suitability in power supply design applications.
ANN Based PID Controlled Brushless DC drive SystemIDES Editor
Brushless (BLDC) DC motors find many industrial
applications such as process control, robotics, automation,
aerospace etc. Wider usage of this system has demanded an
optimum position control for high efficiency, accuracy and
reliability. Hence for the effective position control, estimation
of dynamic load parameters i.e. moment of inertia and friction
coefficient is necessary. This paper incorporates the estimation
of mechanical parameters such as moment of inertia and
friction coefficient of BLDC motor and load at various load
settings by using simple procedure. To achieve the optimum
position control, PID controller is employed and tuned using
PARR method. ANN training is used for obtaining the
mechanical and PID controller parameters at different load
settings. Closed loop position control system of the BLDC
drive system is created using SIMULINK. Simulation results
of this system are obtained at different load settings. It is
evident from the results that the position control system
responds to the desired position with minimum rise time,
settling time and peak overshoot.
Comparative Performance Study for Closed Loop Operation of an Adjustable Spee...IJPEDS-IAES
In this paper an extensive comparative study is carried out between PI
and PID controlled closed loop model of an adjustable speed Permanent
Magnet Synchronous Motor (PMSM) drive. The incorporation of Sinusoidal
Pulse Width Modulation (SPWM) strategy establishes near sinusoidal
armature phase currents and comparatively less torque ripples without
sacrificing torque/weight ratio. In this closed loop model of PMSM drive, the
information about reference speed is provided to a speed controller, to ensure
that actual drive speed tracks the reference speed with ideally zero steady
state speed error. The entire model of PMSM closed loop drive is divided
into two loops, inner loop current and outer loop speed. By taking the
different combinations of two classical controllers (PI & PID) related with
two loop control structure, different approximations are carried out. Hence a
typical comparative study is introduced to familiar with the different
performance indices of the system corresponding to time domain and
frequency domain specifications. Therefore overall performance of closed
loop PMSM drive is tested and effectiveness of controllers will be
determined for different combinations.
Self-Tuning Fuzzy Based PI Controller for DFIM Powered by Two Matrix ConvertersIJPEDS-IAES
This paper presents a study of the Doubly Fed Induction Machine (DFIM) powered by two matrix converters; one connected to the stator windings and the other connected to the rotor windings. First, the mathematical model of DFIM and those of the matrix converters are developed. Then, the vector control technique is applied to the DFIM. Fuzzy logic is used in order to automatically adjust the parameters of the PI controller. The performance of this structure under different operating conditions is studied. Particular interest is given to the robustness of the fuzzy logic based control. The operation of the DFIM under overload conditions is also examined. Simulation results obtained in MATLAB/Simulink environment are presented and discussed.
This document describes a control strategy for a PWM voltage source converter (PWM-VSC) using fuzzy logic to provide variable DC voltage for controlling the speed of a DC motor. A fuzzy logic controller is proposed to minimize errors in the DC voltage and stabilize it by regulating the amplitude of the network current. Simulation results show the fuzzy logic controller produces a stable DC voltage without overshoot to drive the DC motor, with less than 5% total harmonic distortion in the network current and a power factor near unity. The DC motor speed is also stable without overshoot in response to variations in the controlled DC voltage.
Multi-Machine Stability Using Dynamic Inversion Technique IJECEIAES
Stability studies of multi machine system are a major concern to power system engineers due to the increasing complexity involved. This paper deals with the application of a nonlinear technique called Dynamic Inversion, to TCSC for the improvement of stability of multi-machine system. The transient stability studies for various cases: without any controller, with 75% line compensation and with Dynamic Inversion technique, are compared. The critical clearing time as well as the maximum loading ability is also discussed. The result for the nonlinear controller is found to be better than all the other cases.
Constant Frequency Torque Controller for DTC with Multilevel Inverter of Indu...IJPEDS-IAES
Direct Torque Control using multilevel inverter (DTC-MLI) with hysteresis
controller suffers from high torque and flux ripple and variable switching
frequency. In this paper, a constant frequency torque controller is proposed to
enhance the DTC-MLI performance. The operational concepts of the
constant switching frequency torque controller of a DTC-MLI system
followed by the simulation results and analysis are presented. The proposed
system significantly improves the DTC drive in terms of dynamic
performance, smaller torque and flux ripple, and retains a constant switching
frequency.
PID Controller Response to Set-Point Change in DC-DC Converter ControlIAES-IJPEDS
Power converter operations and efficiency is affected by variation in supply
voltage, loads current, circuit elements, ageing and temperature. To meet the
objective of tight voltage regulation, power converters circuit module and the
control unit must be robust to reject disturbances arising from supply, load
variation and changes in circuit elements. PID controller has been the most
widely used in power converter control. This paper presents studies of
robustness of PID controller tuning methods to step changes in the set point
and disturbance rejection in power converter control. A DC-DC boost
converter was modelled using averaged state-space mothod and PID
controllers were designed with five different tuning methods. The study
reveals the transient response and disturbance rejection capability of each
tuning methods for their suitability in power supply design applications.
ANN Based PID Controlled Brushless DC drive SystemIDES Editor
Brushless (BLDC) DC motors find many industrial
applications such as process control, robotics, automation,
aerospace etc. Wider usage of this system has demanded an
optimum position control for high efficiency, accuracy and
reliability. Hence for the effective position control, estimation
of dynamic load parameters i.e. moment of inertia and friction
coefficient is necessary. This paper incorporates the estimation
of mechanical parameters such as moment of inertia and
friction coefficient of BLDC motor and load at various load
settings by using simple procedure. To achieve the optimum
position control, PID controller is employed and tuned using
PARR method. ANN training is used for obtaining the
mechanical and PID controller parameters at different load
settings. Closed loop position control system of the BLDC
drive system is created using SIMULINK. Simulation results
of this system are obtained at different load settings. It is
evident from the results that the position control system
responds to the desired position with minimum rise time,
settling time and peak overshoot.
Comparative Performance Study for Closed Loop Operation of an Adjustable Spee...IJPEDS-IAES
In this paper an extensive comparative study is carried out between PI
and PID controlled closed loop model of an adjustable speed Permanent
Magnet Synchronous Motor (PMSM) drive. The incorporation of Sinusoidal
Pulse Width Modulation (SPWM) strategy establishes near sinusoidal
armature phase currents and comparatively less torque ripples without
sacrificing torque/weight ratio. In this closed loop model of PMSM drive, the
information about reference speed is provided to a speed controller, to ensure
that actual drive speed tracks the reference speed with ideally zero steady
state speed error. The entire model of PMSM closed loop drive is divided
into two loops, inner loop current and outer loop speed. By taking the
different combinations of two classical controllers (PI & PID) related with
two loop control structure, different approximations are carried out. Hence a
typical comparative study is introduced to familiar with the different
performance indices of the system corresponding to time domain and
frequency domain specifications. Therefore overall performance of closed
loop PMSM drive is tested and effectiveness of controllers will be
determined for different combinations.
Self-Tuning Fuzzy Based PI Controller for DFIM Powered by Two Matrix ConvertersIJPEDS-IAES
This paper presents a study of the Doubly Fed Induction Machine (DFIM) powered by two matrix converters; one connected to the stator windings and the other connected to the rotor windings. First, the mathematical model of DFIM and those of the matrix converters are developed. Then, the vector control technique is applied to the DFIM. Fuzzy logic is used in order to automatically adjust the parameters of the PI controller. The performance of this structure under different operating conditions is studied. Particular interest is given to the robustness of the fuzzy logic based control. The operation of the DFIM under overload conditions is also examined. Simulation results obtained in MATLAB/Simulink environment are presented and discussed.
Improved Transient Compensation using PI-SRF Control Scheme Based UHVDC for O...IRJET Journal
This document presents a PI controller-based unified high voltage direct current (UHVDC) system for offshore wind power plants to improve transient compensation. The proposed UHVDC system includes both series and shunt compensators to provide symmetrical and asymmetrical fault handling, smooth power transfer, regulated DC link voltage, and improved reliability. A PI controller using synchronous reference frame (SRF) control is proposed to achieve fast transient management. Simulation results in MATLAB/Simulink show the PI-SRF control technique regulates the DC link voltage and reduces transients during faults compared to conventional control schemes. The control strategy independently controls the shunt and series compensators to maintain power flow and voltage stability under normal and fault conditions.
Joint State and Parameter Estimation by Extended Kalman Filter (EKF) techniqueIJERD Editor
In order to increase power system stability and reliability during and after disturbances, power grid
global and local controllers must be developed. SCADA system provides steady and low sampling density. To
remove these limitation PMUs are being rapidly adopted worldwide. Dynamic states of power system can be
estimated using EKF. This requires field excitation as input which may not available. As a result, the EKF with
unknown inputs proposed for identifying and estimating the states and the unknown inputs of the synchronous
machine.
This document proposes a digital state feedback control method for current control of parallel DC-DC converters. It derives the digital state feedback controller structures for both continuous and discrete time domains using a pole placement technique. This allows precise current sharing among converter modules while meeting performance specifications. It provides examples applying this control scheme to a bidirectional converter for a 42V/14V automotive system in continuous time and a parallel buck converter in discrete time. Both examples are implemented on a DSP to verify the proposed control method.
onlinear Compensation Empyoing Matrix Converter with DTC Controller Yayah Zakaria
This document describes a nonlinear compensation method using a matrix converter with direct torque control (DTC) for an induction motor. The matrix converter combined with DTC aims to reduce torque ripples and minimize steady state error. The simulation results show that the proposed technique of a matrix converter with a fixed switching frequency DTC scheme is effective at reducing torque noise and suppressing steady state error in the motor's input torque. Key aspects of the direct torque control, matrix converter, and their combination are discussed, along with simulation results analyzing the induction motor drive performance.
Performance Analysis of a DTC and SVM Based Field- Orientation Control Induct...IJPEDS-IAES
This study presents a performance analysis of two most popular control strategies for Induction Motor (IM) drives: direct torque control (DTC) and space vector modulation (SVM) strategies. The performance analysis is done by applying field-orientation control (FOC) technique because of its good dynamic response. The theoretical principle, simulation results are discussed to study the dynamic performances of the drive system for individual control strategies using actual parameters of induction motor. A closed loop PI controller scheme has been used. The main purpose of this study is to minimize ripple in torque response curve and to achieve quick speed response as well as to investigate the condition for optimum performance of induction motor drive. Depending on the simulation results this study also presents a detailed comparison between direct torque control and space vector modulation based field-orientation control method for the induction motor drive.
Experiment based comparative analysis of stator current controllers using pre...journalBEEI
The stator current control loop plays an important role in ensuring the quality of electric drives interm of producing fast and adequate required torque. When the current controller provides ideal responses, speed control design subsequently is in charge of improving the system performances. Classical PID control is commonly used in current loop design, this paper presents the comparative analysis of current stator controller using proportional integral control and predictive current control (PCC) in field-oriented control-based induction motor drives, with rigidly coupled loads. The experimental results show system responses with PID and PCC. Informative experiment-based analysis provides primary guidance in selection between the two controls.
Development of a low cost test rig for standalone wecs subject to electrical ...ISA Interchange
This document describes the development of a low-cost test rig for evaluating fault diagnosis techniques for wind turbine generators (WTGs). The test rig uses a DC motor coupled to a self-excited induction generator (SEIG) and interfaced with a wind turbine model in LabVIEW. It is able to simulate the varying wind conditions seen by real WTGs. The document presents the modeling of the wind turbine, DC motor control strategy, SEIG modeling, and integration of the system instrumentation. It is shown that the test rig can effectively test fault diagnosis methods for the SEIG under non-stationary conditions like those experienced by WTGs. In particular, the paper evaluates the use of wavelet transform analysis for detecting
The document discusses power system stabilizers (PSS) and provides context for the thesis. It summarizes that the thesis will investigate modifying the input signal of a specific type of PSS and apply it to a power system to damp low frequency oscillations, without providing an exhaustive literature review. Details of the PSS structure, tuning methods, and considered input signals are given in later chapters.
This document discusses using a STATCOM to damp power system oscillations in a single machine infinite bus system modeled in MATLAB. It presents a Phillips-Heffron model of the system connected to a STATCOM. The linearized model is developed and a POD controller is designed for the STATCOM to improve damping. Simulations are run in MATLAB at different load levels, and the eigenvalues and machine angular frequency responses are presented, showing the STATCOM with POD controller significantly improves damping compared to without the controller.
The document presents two modified control schemes for grid-connected doubly fed induction generators (DFIG) under unbalanced voltage dips. The proposed schemes use PI controllers with anti-windup to determine the commanded rotor currents for active and reactive power control. Notch filters are used to eliminate current harmonics and improve torque stability. One scheme uses PWM current control while the other uses hysteresis current control. Simulations show the proposed methods enhance torque response stability and improve current waveforms compared to traditional control methods under unbalanced voltage dips.
A Lyapunov Based Approach to Enchance Wind Turbine Stabilityijeei-iaes
This paper introduces a nonlinear control of a wind turbine based on a Double Feed Induction Generator. The Rotor Side converter is controlled by using field oriented control and Backstepping strategy to enhance the dynamic stability response. The Grid Side converter is controlled by a sliding mode. These methods aim to increase dynamic system stability for variable wind speed. Hence, The Doubly Fed Induction Generator (DFIG) is studied in order to illustrate its behavior in case of severe disturbance, and its dynamic response in grid connected mode for variable speed wind operation. The model is presented and simulated under Matlab/ Simulink.
Real time simulation of nonlinear generalized predictive control for wind ene...ISA Interchange
In order to make a wind power generation truly cost-effective and reliable, an advanced control techniques must be used. In this paper, we develop a new control strategy, using nonlinear generalized predictive control (NGPC) approach, for DFIG-based wind turbine. The proposed control law is based on two points: NGPC-based torque-current control loop generating the rotor reference voltage and NGPC-based speed control loop that provides the torque reference. In order to enhance the robustness of the controller, a disturbance observer is designed to estimate the aerodynamic torque which is considered as an unknown perturbation. Finally, a real-time simulation is carried out to illustrate the performance of the proposed controller.
Modeling and Simulation of power system using SMIB with GA based TCSC controllerIOSR Journals
This document summarizes a study that uses genetic algorithms to tune a thyristor-controlled series compensator (TCSC) controller to improve the stability of a single-machine infinite-bus (SMIB) power system model. The study models the SMIB system and implements a TCSC to damp oscillations. Genetic algorithms are used to optimize the TCSC controller parameters. Simulation results show that the genetically-tuned TCSC controller more effectively damps oscillations compared to the system without a TCSC controller.
OPTIMAL TORQUE RIPPLE CONTROL OF ASYNCHRONOUS DRIVE USING INTELLIGENT CONTROL...elelijjournal
This document summarizes a research paper on optimizing torque ripple in an asynchronous drive using intelligent controllers. It describes using a hybrid controller combining PI and fuzzy logic control with direct torque control and space vector modulation of a three-level cascaded inverter to power an induction motor drive. Simulation results showed the hybrid controller approach minimized torque ripple compared to using just PI or fuzzy logic control alone under no-load and loaded conditions. The optimized torque control method provides benefits for general purpose induction motor applications.
Development of Predictive Current Controller for Multi-Port DC/DC ConverterIJPEDS-IAES
This paper investigates the utilization of a predictive current control for a four port DC/DC
power electronic converter with an input port, two storage ports and a load port suitable
for a Hybrid Electric Vehicle. Being a power converter with multiple ports, it has different
operating modes. While the Stateflow controller is employed to handle mode selection,
the predictive current controller is used to control the inductor current . The control laws
governing each operating mode is derived out for valley current control. By making the
inductor current in the upcoming switching cycle equivalent to the reference, the duty cycle
is predicted. Simulation and experimental results show improvements in current ripple
minimization, faster dynamic performance and comparable to traditional PI control method.
DTC Scheme for a Four-Switch Inverter-Fed PMBLDC Motor Emulating the Six-Swit...IJRST Journal
The paper deals with the direct torque control (DTC) of brushless DC (BLDC) motor drives fed by four-switch three phase inverters (FSTPI) rather than six-switch inverters (SSTPI) in conventional drives. For any three phase inverter require six switches, but these switches are reduced to four. This reduction of power switches from six to four improves the reliability of the inverter, size of the inverter is reduced and cost of the inverter is also reduces. The FSTPI could be regarded as a reconfigured topology of the SSTPI in case of a switch/leg failure which represents a crucial reliability benefit for many applications especially in electric and hybrid propulsion systems. The DTC of FSTPI-fed BLDC motor drives is treated considering two strategies, such as: 1) DTC-1: a strategy inspired from the one intended to SSTPI-fed BLDC motor drives; 2) DTC-2: a strategy that considers a dedicated vector selection subtable in order to independently control the torques developed by the phases connected to the FSTPI legs during their simultaneous conduction. The operational principle of the four-switch BLDC motor drive and the developed control scheme are theoretically analyzed and the performance is demonstrated by simulation.
A Three-to-Five-Phase Matrix Converter BasedFive- Phase Induction Motor Drive...idescitation
This paper presents a five-phase induction motor drive
system fed from a three-to-five-phase matrix converter. This
is a new concept of generating variable voltage and variable
frequency five-phase output using a special matrix converter.
This matrix converter is proposed recently which transform
the available three-phase supply to five-phase supply. Simple
carrier-based PWM scheme with enhanced approach is
employed to control the output of the matrix converter.
Enhanced approach is utilized so as to increase the output
voltage magnitude of the three-to-five-phase matrix converter.
The motor is controlled in constant v/f mode. Simulation study
is carried out for excitation, acceleration, loadingand reversing
transients. High quality dynamics are observed.
Study of PID Controllers to Load Frequency Control Systems with Various Turbi...IJERA Editor
This document discusses the use of PID controllers for load frequency control (LFC) systems with various turbine models. It first provides background on LFC and the objectives of maintaining constant system frequency. It then describes using PID controllers with different tuning methods, including Ziegler-Nichols and Integral Model Controller, for LFC systems with non-reheat, reheat, and hydro turbines. The document presents the transfer functions for these various turbine models. It also discusses designing PID controllers both with and without the droop characteristic to improve damping. The goal is to study PID controller design methods and tuning to improve the performance of LFC systems with different turbine types.
This document summarizes research into improving transient stability in power transmission systems using a Static VAR Compensator (SVC) with a hybrid PI-Fuzzy Logic controller. It begins with an introduction to Flexible AC Transmission Systems (FACTS) and the role of SVC devices in voltage control and reactive power compensation. It then describes modeling an SVC and the operating principles of conventional PI control. The limitations of PI control for nonlinear systems are discussed. The document proposes a hybrid PI-Fuzzy Logic controller to combine the advantages of both. Simulation results using MATLAB on a 2-machine 3-bus test system show the hybrid controller improves performance during disturbances over PI or Fuzzy Logic control alone.
Design Of Sub Synchronous Damping Controller (SSDC) For TCSC To Improve Power...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
This paper proposes using a genetic algorithm to determine the optimal location of a thyristor controlled series capacitor (TCSC) device to enhance available transfer capability (ATC) between source and sink areas in a deregulated power system. The paper simulates placing a TCSC in the IEEE 14-bus test system and uses repeated power flow calculations to compute the ATC with and without the TCSC to determine how much it can enhance transmission capacity.
Optimization of the Thyristor Controlled Phase Shifting Transformer Using PSO...IJECEIAES
This document summarizes an article that investigates optimizing the placement and sizing of a Thyristor Controlled Phase Shifting Transformer (TCPST) and Thyristor Controlled Series Capacitor (TCSC) combination on a 30-bus power system using a Particle Swarm Optimization (PSO) algorithm. The PSO algorithm was used to determine the optimal location and ratings of the TCPST-TCSC devices to minimize power losses. Implementing the optimized TCPST-TCSC combination resulted in a 46.47% reduction in power losses, outperforming the use of capacitor banks alone which achieved a 42.03% reduction. The TCPST-TCSC solution found with PSO also performed
Improved Transient Compensation using PI-SRF Control Scheme Based UHVDC for O...IRJET Journal
This document presents a PI controller-based unified high voltage direct current (UHVDC) system for offshore wind power plants to improve transient compensation. The proposed UHVDC system includes both series and shunt compensators to provide symmetrical and asymmetrical fault handling, smooth power transfer, regulated DC link voltage, and improved reliability. A PI controller using synchronous reference frame (SRF) control is proposed to achieve fast transient management. Simulation results in MATLAB/Simulink show the PI-SRF control technique regulates the DC link voltage and reduces transients during faults compared to conventional control schemes. The control strategy independently controls the shunt and series compensators to maintain power flow and voltage stability under normal and fault conditions.
Joint State and Parameter Estimation by Extended Kalman Filter (EKF) techniqueIJERD Editor
In order to increase power system stability and reliability during and after disturbances, power grid
global and local controllers must be developed. SCADA system provides steady and low sampling density. To
remove these limitation PMUs are being rapidly adopted worldwide. Dynamic states of power system can be
estimated using EKF. This requires field excitation as input which may not available. As a result, the EKF with
unknown inputs proposed for identifying and estimating the states and the unknown inputs of the synchronous
machine.
This document proposes a digital state feedback control method for current control of parallel DC-DC converters. It derives the digital state feedback controller structures for both continuous and discrete time domains using a pole placement technique. This allows precise current sharing among converter modules while meeting performance specifications. It provides examples applying this control scheme to a bidirectional converter for a 42V/14V automotive system in continuous time and a parallel buck converter in discrete time. Both examples are implemented on a DSP to verify the proposed control method.
onlinear Compensation Empyoing Matrix Converter with DTC Controller Yayah Zakaria
This document describes a nonlinear compensation method using a matrix converter with direct torque control (DTC) for an induction motor. The matrix converter combined with DTC aims to reduce torque ripples and minimize steady state error. The simulation results show that the proposed technique of a matrix converter with a fixed switching frequency DTC scheme is effective at reducing torque noise and suppressing steady state error in the motor's input torque. Key aspects of the direct torque control, matrix converter, and their combination are discussed, along with simulation results analyzing the induction motor drive performance.
Performance Analysis of a DTC and SVM Based Field- Orientation Control Induct...IJPEDS-IAES
This study presents a performance analysis of two most popular control strategies for Induction Motor (IM) drives: direct torque control (DTC) and space vector modulation (SVM) strategies. The performance analysis is done by applying field-orientation control (FOC) technique because of its good dynamic response. The theoretical principle, simulation results are discussed to study the dynamic performances of the drive system for individual control strategies using actual parameters of induction motor. A closed loop PI controller scheme has been used. The main purpose of this study is to minimize ripple in torque response curve and to achieve quick speed response as well as to investigate the condition for optimum performance of induction motor drive. Depending on the simulation results this study also presents a detailed comparison between direct torque control and space vector modulation based field-orientation control method for the induction motor drive.
Experiment based comparative analysis of stator current controllers using pre...journalBEEI
The stator current control loop plays an important role in ensuring the quality of electric drives interm of producing fast and adequate required torque. When the current controller provides ideal responses, speed control design subsequently is in charge of improving the system performances. Classical PID control is commonly used in current loop design, this paper presents the comparative analysis of current stator controller using proportional integral control and predictive current control (PCC) in field-oriented control-based induction motor drives, with rigidly coupled loads. The experimental results show system responses with PID and PCC. Informative experiment-based analysis provides primary guidance in selection between the two controls.
Development of a low cost test rig for standalone wecs subject to electrical ...ISA Interchange
This document describes the development of a low-cost test rig for evaluating fault diagnosis techniques for wind turbine generators (WTGs). The test rig uses a DC motor coupled to a self-excited induction generator (SEIG) and interfaced with a wind turbine model in LabVIEW. It is able to simulate the varying wind conditions seen by real WTGs. The document presents the modeling of the wind turbine, DC motor control strategy, SEIG modeling, and integration of the system instrumentation. It is shown that the test rig can effectively test fault diagnosis methods for the SEIG under non-stationary conditions like those experienced by WTGs. In particular, the paper evaluates the use of wavelet transform analysis for detecting
The document discusses power system stabilizers (PSS) and provides context for the thesis. It summarizes that the thesis will investigate modifying the input signal of a specific type of PSS and apply it to a power system to damp low frequency oscillations, without providing an exhaustive literature review. Details of the PSS structure, tuning methods, and considered input signals are given in later chapters.
This document discusses using a STATCOM to damp power system oscillations in a single machine infinite bus system modeled in MATLAB. It presents a Phillips-Heffron model of the system connected to a STATCOM. The linearized model is developed and a POD controller is designed for the STATCOM to improve damping. Simulations are run in MATLAB at different load levels, and the eigenvalues and machine angular frequency responses are presented, showing the STATCOM with POD controller significantly improves damping compared to without the controller.
The document presents two modified control schemes for grid-connected doubly fed induction generators (DFIG) under unbalanced voltage dips. The proposed schemes use PI controllers with anti-windup to determine the commanded rotor currents for active and reactive power control. Notch filters are used to eliminate current harmonics and improve torque stability. One scheme uses PWM current control while the other uses hysteresis current control. Simulations show the proposed methods enhance torque response stability and improve current waveforms compared to traditional control methods under unbalanced voltage dips.
A Lyapunov Based Approach to Enchance Wind Turbine Stabilityijeei-iaes
This paper introduces a nonlinear control of a wind turbine based on a Double Feed Induction Generator. The Rotor Side converter is controlled by using field oriented control and Backstepping strategy to enhance the dynamic stability response. The Grid Side converter is controlled by a sliding mode. These methods aim to increase dynamic system stability for variable wind speed. Hence, The Doubly Fed Induction Generator (DFIG) is studied in order to illustrate its behavior in case of severe disturbance, and its dynamic response in grid connected mode for variable speed wind operation. The model is presented and simulated under Matlab/ Simulink.
Real time simulation of nonlinear generalized predictive control for wind ene...ISA Interchange
In order to make a wind power generation truly cost-effective and reliable, an advanced control techniques must be used. In this paper, we develop a new control strategy, using nonlinear generalized predictive control (NGPC) approach, for DFIG-based wind turbine. The proposed control law is based on two points: NGPC-based torque-current control loop generating the rotor reference voltage and NGPC-based speed control loop that provides the torque reference. In order to enhance the robustness of the controller, a disturbance observer is designed to estimate the aerodynamic torque which is considered as an unknown perturbation. Finally, a real-time simulation is carried out to illustrate the performance of the proposed controller.
Modeling and Simulation of power system using SMIB with GA based TCSC controllerIOSR Journals
This document summarizes a study that uses genetic algorithms to tune a thyristor-controlled series compensator (TCSC) controller to improve the stability of a single-machine infinite-bus (SMIB) power system model. The study models the SMIB system and implements a TCSC to damp oscillations. Genetic algorithms are used to optimize the TCSC controller parameters. Simulation results show that the genetically-tuned TCSC controller more effectively damps oscillations compared to the system without a TCSC controller.
OPTIMAL TORQUE RIPPLE CONTROL OF ASYNCHRONOUS DRIVE USING INTELLIGENT CONTROL...elelijjournal
This document summarizes a research paper on optimizing torque ripple in an asynchronous drive using intelligent controllers. It describes using a hybrid controller combining PI and fuzzy logic control with direct torque control and space vector modulation of a three-level cascaded inverter to power an induction motor drive. Simulation results showed the hybrid controller approach minimized torque ripple compared to using just PI or fuzzy logic control alone under no-load and loaded conditions. The optimized torque control method provides benefits for general purpose induction motor applications.
Development of Predictive Current Controller for Multi-Port DC/DC ConverterIJPEDS-IAES
This paper investigates the utilization of a predictive current control for a four port DC/DC
power electronic converter with an input port, two storage ports and a load port suitable
for a Hybrid Electric Vehicle. Being a power converter with multiple ports, it has different
operating modes. While the Stateflow controller is employed to handle mode selection,
the predictive current controller is used to control the inductor current . The control laws
governing each operating mode is derived out for valley current control. By making the
inductor current in the upcoming switching cycle equivalent to the reference, the duty cycle
is predicted. Simulation and experimental results show improvements in current ripple
minimization, faster dynamic performance and comparable to traditional PI control method.
DTC Scheme for a Four-Switch Inverter-Fed PMBLDC Motor Emulating the Six-Swit...IJRST Journal
The paper deals with the direct torque control (DTC) of brushless DC (BLDC) motor drives fed by four-switch three phase inverters (FSTPI) rather than six-switch inverters (SSTPI) in conventional drives. For any three phase inverter require six switches, but these switches are reduced to four. This reduction of power switches from six to four improves the reliability of the inverter, size of the inverter is reduced and cost of the inverter is also reduces. The FSTPI could be regarded as a reconfigured topology of the SSTPI in case of a switch/leg failure which represents a crucial reliability benefit for many applications especially in electric and hybrid propulsion systems. The DTC of FSTPI-fed BLDC motor drives is treated considering two strategies, such as: 1) DTC-1: a strategy inspired from the one intended to SSTPI-fed BLDC motor drives; 2) DTC-2: a strategy that considers a dedicated vector selection subtable in order to independently control the torques developed by the phases connected to the FSTPI legs during their simultaneous conduction. The operational principle of the four-switch BLDC motor drive and the developed control scheme are theoretically analyzed and the performance is demonstrated by simulation.
A Three-to-Five-Phase Matrix Converter BasedFive- Phase Induction Motor Drive...idescitation
This paper presents a five-phase induction motor drive
system fed from a three-to-five-phase matrix converter. This
is a new concept of generating variable voltage and variable
frequency five-phase output using a special matrix converter.
This matrix converter is proposed recently which transform
the available three-phase supply to five-phase supply. Simple
carrier-based PWM scheme with enhanced approach is
employed to control the output of the matrix converter.
Enhanced approach is utilized so as to increase the output
voltage magnitude of the three-to-five-phase matrix converter.
The motor is controlled in constant v/f mode. Simulation study
is carried out for excitation, acceleration, loadingand reversing
transients. High quality dynamics are observed.
Study of PID Controllers to Load Frequency Control Systems with Various Turbi...IJERA Editor
This document discusses the use of PID controllers for load frequency control (LFC) systems with various turbine models. It first provides background on LFC and the objectives of maintaining constant system frequency. It then describes using PID controllers with different tuning methods, including Ziegler-Nichols and Integral Model Controller, for LFC systems with non-reheat, reheat, and hydro turbines. The document presents the transfer functions for these various turbine models. It also discusses designing PID controllers both with and without the droop characteristic to improve damping. The goal is to study PID controller design methods and tuning to improve the performance of LFC systems with different turbine types.
This document summarizes research into improving transient stability in power transmission systems using a Static VAR Compensator (SVC) with a hybrid PI-Fuzzy Logic controller. It begins with an introduction to Flexible AC Transmission Systems (FACTS) and the role of SVC devices in voltage control and reactive power compensation. It then describes modeling an SVC and the operating principles of conventional PI control. The limitations of PI control for nonlinear systems are discussed. The document proposes a hybrid PI-Fuzzy Logic controller to combine the advantages of both. Simulation results using MATLAB on a 2-machine 3-bus test system show the hybrid controller improves performance during disturbances over PI or Fuzzy Logic control alone.
Design Of Sub Synchronous Damping Controller (SSDC) For TCSC To Improve Power...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
This paper proposes using a genetic algorithm to determine the optimal location of a thyristor controlled series capacitor (TCSC) device to enhance available transfer capability (ATC) between source and sink areas in a deregulated power system. The paper simulates placing a TCSC in the IEEE 14-bus test system and uses repeated power flow calculations to compute the ATC with and without the TCSC to determine how much it can enhance transmission capacity.
Optimization of the Thyristor Controlled Phase Shifting Transformer Using PSO...IJECEIAES
This document summarizes an article that investigates optimizing the placement and sizing of a Thyristor Controlled Phase Shifting Transformer (TCPST) and Thyristor Controlled Series Capacitor (TCSC) combination on a 30-bus power system using a Particle Swarm Optimization (PSO) algorithm. The PSO algorithm was used to determine the optimal location and ratings of the TCPST-TCSC devices to minimize power losses. Implementing the optimized TCPST-TCSC combination resulted in a 46.47% reduction in power losses, outperforming the use of capacitor banks alone which achieved a 42.03% reduction. The TCPST-TCSC solution found with PSO also performed
The induction motors are indispensable motor types for industrial applications due to its wellknown advantages. Therefore, many kind of control scheme are proposed for induction motors over the past years and direct torque control has gained great importance inside of them due to fast dynamic torque response behavior and simple control structure. This paper suggests a new approach on the direct torque controlled induction motors, Fuzzy logic based space vector
modulation, to overcome disadvantages of conventional direct torque control like high torque ripple. In the proposed approach, optimum switching states are calculated by fuzzy logic
controller and applied by space vector pulse width modulator to voltage source inverter. In order to test and compare the proposed DTC scheme with conventional DTC scheme
simulations, in Matlab/Simulink, have been carried out in different speed and load conditions. The simulation results showed that a significant improvement in the dynamic torque and speed responses when compared to the conventional DTC scheme.
This document presents a comparative study of using a thyristor controlled series capacitor (TCSC) and an induction machine damping unit (IMDU) to dampen subsynchronous resonance (SSR) oscillations in a series compensated power transmission system. The study develops linearized mathematical models of the system components including the generator, transmission line, TCSC, and IMDU. Eigenvalue analysis is performed on the models with and without the TCSC and IMDU to evaluate their effectiveness in damping torsional vibration modes. Time domain simulations under large disturbances also show that the IMDU provides better damping than the TCSC, though the TCSC is also effective and has the added capability of controlling active power flow.
This document presents an optimal supplementary damping controller design for Thyristor Controlled Series Compensator (TCSC) using Real-Coded Genetic Algorithm (RCGA). TCSC is capable of improving power system stability by modulating reactance during disturbances. The document proposes using a multi-objective fitness function consisting of damping factors and real parts of eigenvalues to optimize the parameters of a TCSC-based supplementary damping controller using RCGA. Simulation results presented show the effectiveness of the proposed controller over a wide range of operating conditions and disturbances.
Direct Torque Control (DTC) is widely applied for ac motor drives as it offers high performance torque control with a simple control strategy. However, conventional DTC poses some disadvantages especially in term of variable switching frequency and large torque ripple due to the utilization of torque hysteresis controller. Other than that, performance of conventional DTC fed by two-level inverter is also restricted by the limited numbers of voltage vectors which lead to inappropriate selection of voltage vectors for different speed operations. This research aims to propose a Constant Switching Frequency (CSF) torque controller for DTC of induction motor (IM) fed by three-level Neutral-Point Clamped (NPC) inverter. The proposed torque controller utilizes PI controller which apply different gain for different speed operation. Besides, the utilization of NPC inverter provides greater number of voltage vectors which allow appropriate selection of voltage vectors for different operating condition. Using the proposed method, the improvement of DTC drives in term of producing a constant switching operation and minimizing torque ripple are achieved and validated via experimental results.
1) The document proposes a new inverter design for Flexible AC Transmission System (FACTS) applications to improve efficiency.
2) The proposed inverter uses fewer switches than conventional cascaded H-bridge multilevel inverters, reducing switching losses. It produces 7 voltage levels using only 8 switches and 4 DC sources, whereas conventional designs require 12 switches and 3 DC sources.
3) Simulation results show that the proposed inverter produces voltage waveforms with lower harmonic content when used in a Static Synchronous Series Compensator (SSSC) FACTS controller, demonstrating its potential to improve FACTS system performance with reduced complexity.
A NEW FUZZY LOGIC BASED SPACE VECTOR MODULATION APPROACH ON DIRECT TORQUE CON...csandit
The induction motors are indispensable motor types for industrial applications due to its wellknown
advantages. Therefore, many kind of control scheme are proposed for induction motors
over the past years and direct torque control has gained great importance inside of them due to
fast dynamic torque response behavior and simple control structure. This paper suggests a new
approach on the direct torque controlled induction motors, Fuzzy logic based space vector
modulation, to overcome disadvantages of conventional direct torque control like high torque
ripple. In the proposed approach, optimum switching states are calculated by fuzzy logic
controller and applied by space vector pulse width modulator to voltage source inverter. In
order to test and compare the proposed DTC scheme with conventional DTC scheme
simulations, in Matlab/Simulink, have been carried out in different speed and load conditions.
The simulation results showed that a significant improvement in the dynamic torque and speed
responses when compared to the conventional DTC scheme.
Steady state stability analysis and enhancement of three machine nine bus pow...eSAT Journals
This document presents an analysis of steady state stability for the IEEE 3-machine 9-bus test power system. It first describes the mathematical modeling of the system using linearization and state space representation. Eigenvalue analysis shows the system is purely oscillatory without damping. A thyristor controlled phase shifter (TCPS) FACTS device-based controller is then modeled to enhance stability. The system is analyzed with and without the controller. Results show the controller provides damping, improving stability as seen in eigenvalue analysis and time domain simulations following a disturbance.
Non-integer IMC Based PID Design for Load Frequency Control of Power System t...IJECEIAES
This paper deals with non-integer internal model control (FIMC) based proportional- integral-derivative(PID) design for load frequency control (LFC) of single area nonreheated thermal power system under parameter divergence and random load disturbance. Firstly, a fractional second order plus dead time(SOPDT) reduced system model is obtained using genetic algorithm through step error minimization. Secondly, a FIMC based PID controller is designed for single area power system based on reduced system model. Proposed controller is equipped with single area non-reheated thermal power system. The resulting controller is tested using MATLAB/SIMULINK under various conditions. The simulation results show that the controller can accommodate system parameter uncertainty and load disturbance. Further, simulation shows that it maintains robust performance as well as minimizes the effect of load fluctuations on frequency deviation. Finally, the proposed method applied to two area power system to show the effectiveness.
Enhancement of Power System Dynamics Using a Novel Series Compensation SchemeIJMER
Phase imbalanced capacitive compensation is a “hybrid” series compensation scheme, where the
series capacitive compensation in one phase is created using a single-phase TCSC in series with a fixed capacitor
(Cc), and the other two phases are compensated by fixed series capacitors (C). The TCSC control is initially set
such that its equivalent compensations at the power frequency combined with the fixed capacitor yield a
resultant compensation equal to the other two phases. Thus, the phase balance is maintained at the power
frequency while at any other frequency, a phase imbalance is created. The effectiveness of the scheme in damping
power system oscillations for various network conditions, namely different system faults and tie-line power flows is
evaluated using the MATLAB/SIMULINK Software
Tuning of PI and PID Controller with STATCOM, SSSC and UPFC for Minimizing Da...IOSRJEEE
This paper presents the comparative performance of directly and feedback connected PI and PID controller scheme with Flexible AC Transmission System (FACTS) devices, such as Static Synchronous Compensator (STATCOM), Static Synchronous Series Compensator (SSSC) and Unified Power Flow Controller (UPFC) in terms of improvements in transient stability, extenuation of system oscillations and furnishing voltage support in single machine infinite bus system (SMIB). Firstly, rotor angle deviation and speed deviation analyzed for directly connected PI and PID with UPFC, SSSC and STATCOM then for feedback connected. The comparisons of all the results are performed using Matlab simulink in term of maximum overshoot and settling time.
1) The document proposes an enhanced direct torque control strategy for induction motor drives based on an imaginary swapping instant concept.
2) Simulation results show the proposed technique improves performance over conventional direct torque control, reducing torque and flux ripples by over 60% and speeding transient response times.
3) Benefits of the proposed technique include better robustness against parameter and load variations across low and high speed ranges.
A Review of Analysis and Modeling of Grid Connected Three Phase Multilevel Un...IRJET Journal
This document reviews a five-level multiple-pole structure for a grid connected three phase multilevel unity power rectifier that aims to improve power factor and reduce total harmonic distortion using fewer components. The proposed design is a five-level/multiple-pole multilevel unity power factor rectifier that achieves unity power factor and input current shaping with a reduced number of components. It uses a simple control method based on average current control at a low switching frequency to compensate for grid current harmonics. Simulation results show the design has better dynamic response and tracking under unbalanced grid conditions compared to other existing rectifier topologies.
Simulation, bifurcation, and stability analysis of a SEPIC converter control...IJECEIAES
This article presents some results of SEPIC converter dynamics when controlled by a center pulse width modulator controller (CPWM). The duty cycle is calculated using the ZAD (Zero Average Dynamics) technique. Results obtained using this technique show a great variety of non-linear phenomena such as bifurcations and chaos, as parameters associated with the switching surface. These phenomena have been studied in the present paper in numerical form. Simulations were done in MATLAB.
In this paper, a new topology of Adaptive Hysteresis Band controller for Boost & Buck converter has been proposed, modeled and analyzed. The difficulties caused in Hysteresis Band (HB) controlled dc-dc converter have been eliminated using Adaptive Hysteresis Band (AHB) controller. This novel control topology can be able to maintain the switching frequency constant unlike HB controller. Thus the filter design for the converters will become easier with this controller. Again this control methodology is a robust one as it depends upon the system parameters where there was no possibility with HB controller. The Mathematical modeling of the controller is shown in this paper, further this has been simulated using Matlab /SIMULINK to generate pulse. The steady state analysis to find the parameters and the stability condition of the converter using the dynamic behavior is also portrayed in this paper. The simulation for a Boost and a Buck converter is also shown separately using AHB controller.
A Novel Direct Torque Control for Induction Machine Drive System with Low Tor...IAES-IJPEDS
This document describes a novel direct torque control method for induction machine drives using space vector modulation (DTC-SVM) to reduce torque and flux ripples. Simulation results show the proposed DTC-SVM control achieves lower ripples compared to the conventional DTC method. The DTC-SVM control strategy is designed and simulated using Matlab/Simulink and implemented on an FPGA using Xilinx System Generator. Simulation results verify the DTC-SVM control is effective at minimizing torque and flux ripples for induction machine drives.
Power System MIMO Identification for Coordinated Design of PSS and TCSC Contr...Reza Pourramezan
Authors: Reza Pourramezan, Sadegh Vaez-Zadeh, and Hamid Reza Nourzadeh
Published in 2007 IEEE Power Engineering Society General Meeting (PES)
DOI: 10.1109/PES.2007.385692
Fault Ride-Through capability of DSTATCOM for Distributed Wind Generation SystemIJPEDS-IAES
In this paper, fault ride through analysis of a low voltage distribution system
augmented with distributed wind generation using squirrel cage induction
generator and distribution static compensator (DSTATCOM) is carried out
through modeling and simulation study in MATLAB. The impact of
unbalanced (single line to ground) fault in a low voltage distribution system
in normal and severe conditions is studied and analyzed in details. Analysis
on system instability is also shown in case of sever fault condition. A
distribution Static Compensator (DSTATCOM) is used to improve fault ride
through (FRT) capability of wind generation system by compensating
positive sequence voltage. A comparison of dynamic response of the system
with and without DSTATCOM and effects of DSTATCOM on voltage and
generator speed are presented. The simulation results shows that
DSTATCOM is capable of reducing the voltage dips and improving the
voltage profiles by providing reactive power support to distributed wind
generation system under unbalanced fault condition and enhances the fault
ride through capability of the wind generator.
Similar to QFT Based Controller Design of Thyristor-Controlled Phase Shifter for Power System Stability Enhancement (20)
Injection Analysis of Hera And Betano New Power Plants At the Interconnection...IJRESJOURNAL
ABSTRACT: Electricity system in Timor Leste is supplied from small scale Diesel Power Plants (DPP) which are distributed at each district that not interconnected, as the consequences, electric continuity at some districts are disturbed so caused power outage. To overcome the matters, the steps taken by Timor Leste government by establishing 2 units of centered DPP with total capacity of 250 MW at Dili District of 120 MW and at BetanoDistrict of 130 MW. The new power plant will be injected at the electricity system of Timor Leste through transmission line of 150 kV. The new power plant injection will cause the power flow and system stability of Timor Leste entirely. Steady state analysis done including the power flow analysis before and after injection of DPP of Hera and Betano so can be seen the voltage profile change and the decrease of electric power losses. Beside the steady state analysis, also done the power system stability analysis to know whether the system can operate normally after short circuit disturbance of three phases before and after new DPP injection. The steady state analysis showed that the system voltage condition before injection of DPP of Hera and Betano experience decrease of -13% from the sending voltage, and the active power losses of 6.8%. After DPP of Hera and Betano injection the decrease only -6% and active power losses can be minimized become 5.3%. The results of power system stability showed the rotor angle stability, frequency and voltage stability during disturbance occurrence become more stable after injection with recovery time faster if compared with before injection of new power plant.
Harmonic AnalysisofDistribution System Due to Embedded Generation InjectionIJRESJOURNAL
ABSTRACT:The increased demand for electricity and the depletion of fossil energy sources are a challenge to exploit new and renewable energy sources. Relatively cheap renewable energy sources are Wind Power Plant (WPP) and Photovoltaic System (PV). Currently, many small scale generating plants are being evolved into conventional systems known as Embedded Generation (EG). EG as a source of electricity in the distribution system will affect the flow of system power, system reliability, voltage profile and others. Besides, with the placement of converter technology in WPP and PV system will give contribution of harmonic enhancement to the system. This paper presents the harmonic analysis of WPP and PV designs that are injected into conventional distribution system in one bus at Pujon feeder station Malang, Indonesia. The bus is chosen because in this area the need for electric power in the area is very high and the existing system has a harmonic value of 11%. Hybrid Active Filter (HAF) is designed to lower the voltage harmonics due to EG injection into existing systems without affecting harmonics in other buses. To analyze the harmonics in this study there are 4 scenarios offered: Scenario 1 starts with analysis on existing system, scenario 2 existing in WPP 2 MVA injection, scenario 3, injection1.3 MVA PV, scenario 4 injected EG (WPP and PV). The simulation result using PSCAD 4.5 shows in scenario 4 to generate harmonic voltage of 18.6% and after added with HAF, the harmonic value of the voltage becomes 2.434%
Decision Support System Implementation for Candidate Selection of the Head of...IJRESJOURNAL
ABSTRACT: One of agency under the subdivision of The Indonesian National Army is Bintaldam V Brawijaya, acts as the mental founding agency. The head of affairs position replacement is often occurred in this agency, but the positions currently have a large number of incompetence person in charge. Subjection inthe election process leads to the inaccurate placement, resulting in poor leadership. The process of head of affairs assignment starts from candidates dispatching from each head of administrative section. Those candidates must then meet the three elements of assessment, i.e. the personality element, qualification element, and potential element. The candidates will be selected by head of agency as the top leader in the agency. The head of agency, however, poses difficulties to determine which candidate to put into position, frequently because of no proportional system exists to provide assistance in decision making process. A method is needed tomake more accurate placement for better leadership result.This research utilizegroup technology as the assessment elements hierarchical data structure and decision table as the rule evaluation engine to form a decision support system for making the replacement process of the heads of affairs easier and more accurate.
Yield Forecasting to Sustain the Agricultural Transportation UnderStochastic ...IJRESJOURNAL
ABSTRACT: Agricultural transportation is a major part of the United States’ transportation systems. This system follows a complex multimodal network consisting of highway, railway, and waterways which are mostly based on the yield of the agricultural commodities and their market values. The yield of agricultural commodities is dependent on stochastic environment such as weather conditions, rainfall, soil type and natural disasters. Different techniques such as leaf growth index, Normalized Difference Vegetation Index (NDVI), and regression analysis are used to forecast the yield for the end of harvest season. The yield forecasting techniques are used to predict the agricultural transportation needs and improve the cost minimization. This study provides a model for yield forecasting using NDVI data, Geographical Information System (GIS), and statistical analysis. A case study is presented to demonstrate this model with a novel tool for collecting NDVI data.
Injection Analysis of 5 Mwp Photovoltaic Power Plant on 20 Kv Distribution Ne...IJRESJOURNAL
ABSTRACT : A new 5 MWp PLTS or PV has been built in Oelpuah Village, Kupang Tengah. According to PT. PLN NTT,the amount of injected power to the distribution network cannot reach its maximum capability. At the moment, the average value of injected active power is 2 MWp. In this paper, a solution to achieve maximum injected power will be discussed. As a result of the study, the main problem is absence of energy storage. It cause the output power of the PV strongly affected by the weather. Hence a fluctuation of generated power cannot be avoided. The frequency in the distribution network system can be easily increased or decreased. Sudden drop in frequency due to 5 MWp lost, will cause the frequency to decrease beyond the standard value. The under frequency relay trips because it takes a long time to return to the originalvalue. A 5% of droop setting value is not suitable with those conditions. The droop characteristic setting should be reduced to 1% as a proposed solution. So that the response to frequency changes is more sensitive
Developing A Prediction Model for Tensile Elastic Modulus of Steel Fiber – Ce...IJRESJOURNAL
ABSTRACT: This paper attempts to develop a prediction model that can be used in line with prescribed laboratory experiments for indirect tensile test such that tensile elastic modulus can be predicted for cement stabilized lateritic soil reinforced with steel fiber using measured properties of the material. The results of the tensile elastic modulus obtained from the Derived Prediction Model almost nearly replicates that obtained from calculations from laboratory experimentation. Results obtained revealed that both the predicted values and calculated values have a linear correlation with an R2 of 96.4%. On this basis the Derived Prediction Model can be said to be valid within the limits of the study.
Effect of Liquid Viscosity on Sloshing in A Rectangular TankIJRESJOURNAL
ABSTRACT : Liquid sloshing was investigated for a moving partially filled rectangular tank with/without vertical baffles. A set of experiments was conducted using two types of liquids: water and sunflower oil. For these liquids, the effects of varying the external excitation amplitude and the number of vertical baffles on sloshing are discussed. It was found that the mechanical dissipation due to the liquid viscosity has a remarkable influence on the sloshing characteristics
Design and Implementation Decision Support System using MADM Methode for Bank...IJRESJOURNAL
ABSTRACT: The function of banking process can be broadly defined as an institution functioning as a capital receiver and lender, as well as support for trading and payment transactions. In order to maintain the stability of the economy through lending, Bank Indonesia issued a form letter on March 15, 2012 on the application of risk management for the bank conducting credit. In an effort to minimize these problems, Bank Indonesia recommends the precautionary principle in arranging the loan terms and choose the prospective customer in the credit granting institutions, both banks and cooperatives to take into account the risk on lending. A method is needed to select bank for credit applications to the public, i.e. the customer. This research uses the comparison of MADM (Multiple Attribute Decision Making) between TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method and ELECTRE (ELimination Et Choix TRaduisant la realitE) method for the loan provisions to the customers. With the hope of getting the quickest and the most accurate solutions, the hesitancy in determining customers for lending can then be minimized.
Investigations on The Effects of Different Heat Transfer Coefficients in The ...IJRESJOURNAL
This document discusses a simulation investigating the effects of different heat transfer coefficients on metal machining processes. It presents simulations of turning AISI 1045 steel using three different heat transfer coefficients to represent different cooling techniques. The simulations show that higher heat transfer coefficients decrease chip compression ratio and increase shear angle. They also decrease temperature at the tool-chip interface and increase stress. The heat transfer coefficient significantly impacts chip shape, temperature distribution, stress distribution, and other output variables in metal machining simulations.
Strategy of Adaptation of Traditional House Architecture Bali AgaIJRESJOURNAL
The document discusses the strategy of adaptation of traditional house architecture in Bali Aga's Pengotan village. It finds that traditional houses have undergone changes to building materials and elements over time to adapt to changing needs and environments. Specifically:
1) Houses originally built with bamboo and clay have replaced materials like tile, zinc, asbestos, bricks and concrete due to their durability and availability.
2) Changes started with rooftops and foundations, then walls, as these elements are most exposed to weathering.
3) The process of change occurred gradually over a long period as communities sought to improve their buildings. While materials changed, the basic form and layout adhered to village rules.
Design of Universal Measuring Equipment for Bogie FrameIJRESJOURNAL
The document describes the design of a universal measuring equipment for bogie frames used in metro vehicles. The equipment includes a measuring jig, articulated arm measuring device, and data management software. The measuring jig can adapt to support different bogie frame types and includes adjustable bases to position the frame. An articulated arm measuring device is used for its flexibility and portability. It can accurately measure points on the frame. Data is acquired from sensors on the arm and stored/analyzed using management software, which guides operators through the measurement process. The designed equipment can measure various metro bogie frames to evaluate maintenance quality.
A Design Of Omni-Directional Mobile Robot Based On Mecanum WheelsIJRESJOURNAL
ABSTRACT:As one of the important branch of mobile robotics, wheel mobile robot has long been paid atten tion to by the research people at home and abroad for its high load ability, positioning accuracy, high efficiency, simple control, etc. Mobile robot has close relation to many technologies suc-h as control theory, computer tech nology, sensor technology, etc. Therefore, research on the mobile robot has important significance
An Investigation Into The Prevalence of Code Switching in the Teaching of Nat...IJRESJOURNAL
ABSTRACT: This study examines the functions of code-switching in primary schools by science teachers. In Namibia,English is the official language of instruction for science at primary school. At lower primary, Silozi is the language of instruction. Classroom interaction data was obtained from two science lessons. Analysis of the teachers' code-switching shows that code-switching in the two lessons was vastly different, with little codeswitching in the teacher-facilitated lesson.Evident in other lessons, in which science was taught as a content subjectbut with abstract names that had no corresponding local names in Silozi, there was frequent use of codeswitching for reiteration and message qualification. The direction of the language switch from Silozi to English as well as the proportion of teachersspeaking in English suggests that the official language for teaching is English at upper primary, grade 4 to 7. The science lesson and code-switching is a necessary tool for teachers to achieve teaching goals in content-based lessons involving students who lack proficiency in the instructional language. The study was conducted in five government primary schools in Katima Mulilo, the capital of the Zambezi region in Namibia.The national language is English language, with no exception inscience, mathematics, and language subjects.All Schools are located in a Katima Mulilo-urban. The students are from mixed classes, lower, middle and upper class families with their parents typically working as unemployed single mothers, domestic workers, clerks, nurses, teachers, and accountants. Some of the students could understand English because of their parents‟ educational background or in instances where English is spoken at home.
The Filling Up of Yogyakarta Governor Position in Social Harmony PerspectiveIJRESJOURNAL
ABSTRACT: This paper aims to provide an overview in filling up the position of Governor of Yogyakarta, Distinctive Region, Indonesia, that considering social harmony perspective. Discussion conducts using social harmony perspectives, because the Sultan as the King was suspected to devise making her daughter the Queen who will be automatically the Governor succeeding him. This paper based on sociology legal research, this study approached the legal issues in accordance with the fact in social life, to provide an overview existing condition rules and public perseptions in filling position of Governor of Yogyakarta, especially about gender (female) position. Dataas are collected by interviewed and distributed questionnaires to various groups. Considering the result of research, that the Sultan’s way generated a sufficiently deep polemics in the Palace environment, government and society, so that this even kept away from the customary values of Javanese custom and Islam religion emphasizing on social harmony.
Quality Function Deployment And Proactive Quality Techniques Applied to Unive...IJRESJOURNAL
ABSTRACT: Lecturing and instruction to students at university has traditionally been based on qualifications, experience and position of academics within ones department or college. The higher the level and more advanced the subject then the most experienced lecturers are traditionally selected for that task. Visiting lecturers are never asked to teach basic mathematics or science, they are to share their experience and enlighten the students from a vast knowledge and history. This paper reviews and discusses Kano’s model with Quality Function Deployment related to customer satisfaction and compares if the traditional approach is in keeping with university practice. Furthermore, it argues that industry has concepts and ideas that can be more proactive if applied to an educational environment where students’ demands are ever increasing and their expectations are becoming higher. If universities are to improve student-learning experiences then novel and successful techniques are needed. One such approach is discussed in this research paper to find better ways to improve student satisfaction.
The Analysis And Perspective on Development of Chinese Automotive Heavy-Duty ...IJRESJOURNAL
ABSTRACT: In recent years, under the influence of both China's domestic market demand and emissions standard improvement, Chinese manufacturers put great effort on the research and design of automotive heavy-duty diesel engine. This paper analyzes the technical parameters of heavy duty diesel engine in 11 / 13L displacement section and introduces its performance. At the same time, combined with the development of foreign heavy-duty diesel engine, the future development direction of Chinese heavy-duty diesel engine is forecasted.
Research on the Bottom Software of Electronic Control System in Automobile El...IJRESJOURNAL
ABSTRACT: With the development of science and technology, car replacement faster and faster. The development of the automotive industry has a contradiction, on the one hand, the speed of upgrading the car technology can not keep up with the speed of the performance requirements of the car, on the other hand, the country's automobile exhaust emission standards become more stringent. In addition, the depletion of oil resources led to the rise in gasoline prices, the traditional car is facing a crisis. Considering the situation of gas fuel resource structure and supply situation in China, it is feasible to promote gas fuel engine[1].However, the pollution caused by the car has become one of the major pollution sources in the urban environment and the atmospheric environment, and this trend continues to deteriorate[2].Therefore, alternative energy vehicles and hybrid cars is the main direction of development, and any improvement in the car will be car electronics and software replacement for the premise. On the one hand, natural gas as an alternative to gasoline, with its low prices, excellent combustion emissions, the relative sustainable development and other characteristics of more and more car manufacturers favor;On the other hand, the mainstream of the automotive electronic control unit ECU software development to AUTOSAR structure, low power consumption, functional safety for the development direction. Based on the actual development of natural gas engine control unit, the structure and function of ECU software are studied with reference to AUTOSAR software design standard. This paper studies the structure of the application of the software layer of the electronic control system and the main control strategy under the various conditions of the structure, and puts forward the underlying software resources needed by the application layer software. This paper analyzes the internal and peripheral resources of Infineon XC2785x microcontroller and designs hardware abstraction layer software and ECU abstraction layer software. The current characteristics of the jet valve driven by the natural gas multi-point injection engine were investigated. Automotive electronics technology has been widely used in modern vehicles which, and gradually become the development of new models, improve the performance of the key technical factors[3] .
Risk Based Underwater Inspection (RBUI) For Existing Fixed Platforms In Indon...IJRESJOURNAL
Abstract For existing fixed platforms in Indonesian waters, a method to determine underwater inspection basedon the risk level is needed as an alternative for the conventional time-based underwater inspection. This paper discusses the development of Risk Based Underwater Inspection (RBUI) for Indonesian fixed offshore platforms by adopting the inspection scope from API RP 2A-WSD and API RP 2SIM. The risk will be determined based on the calculated Consequence of Failure (CoF) and Probability of Failure (PoF), and then it will be converted into a relevant inspection interval according to the references. In addition, it had also been discovered that the minimum fatigue of a platform that is shorter than the intended design life appeared to be the major problem of the Indonesian existing platforms. Therefore, this condition would be taken into consideration as a factor to override the preliminary inspection interval plan. Sample of 10 platform data located in Indonesian waters were used for RBUI analysis in this paper.
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A New Approach on Proportional Fuzzy Likelihood Ratio orderings of Triangular...IJRESJOURNAL
ABSTRACT: In this chapter, we introduce a new approach on the concept of proportional fuzzy likelihood ratio orderings, increasing and decreasing proportional fuzzy likelihood ratio orderings of triangular fuzzy random variables are presented. Based on these orderings, some theorems are also established.
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QFT Based Controller Design of Thyristor-Controlled Phase Shifter for Power System Stability Enhancement
1. International Journal of Research in Engineering and Science (IJRES)
ISSN (Online): 2320-9364, ISSN (Print): 2320-9356
www.ijres.org Volume 5 Issue 4 ǁ Apr. 2017 ǁ PP.54-64
www.ijres.org 54 | Page
QFT Based Controller Design of Thyristor-Controlled Phase
Shifter for Power System Stability Enhancement
Ki Sun Han1
, Moon Gyu Jeong1
, Jeong Phil Lee2
1
(Power Transmission Laboratory, Korea Electric Power Corporation Research Institute, Korea)
2
(Subdivision of New &Renewable Electricity, Kyungnam College of Inform.& Tech., Korea)
ABSTRACT: This paper presents the automatic design method for a thyristor-controlled phase shifter (TCPS)
controller based on quantitative feedback theory (QFT) to improve power system stability in spite of system
uncertainties and various disturbances. A genetic algorithm (GA) in a loop shaping state of QFT design has been
used to design the TCPS controller satisfying all QFT bounds without repetition of a manual try and error. The
proposed performance index in GA has been composed of the QFT bounds and the damping ratio. To verify
control performance of the proposed TCPS controller based on QFT using GA, the closed loop eigenvalue and
the damping of power system have been analyzed and nonlinear simulations for a single machine infinite bus
system have been performed under various disturbances for various operating conditions. The control
characteristics of the proposed TCPS controller have been compared with that of the conventional power system
stabilizer (PSS) and conventional TCPC controller. The simulation results show that the proposed TCPS
controller provided better dynamic responses in comparison with the conventional PSS and TCPS controller.
Keywords: Quantitative feedback theory(QFT), genetic algorithm(GA), thyristor-controlled phase shifter
(TCPS), robust control, power system stabilizer (PSS).
I. INTRODUCTION
The complicatedly interconnected power systems have a small signal oscillatory instability
characteristics caused by insufficient natural damping in the system. A power system stabilizer (PSS) has been
widely utilized to damp low frequency oscillation and to improve small signal stability through the
supplementary excitation control of a generator [1-4]. However, a PSS may cause great variations in the voltage
profile, may result in leading power factor and may not be able to suppress oscillation resulting from severe
disturbance [5]. With the recent advances in power electronics technology, the flexible AC transmission system
(FACTS) devices have been installed to enhance power system stability, such as thyristor-controlled series
capacitor (TCSC)[6], static var compensator (SVC)[7], thyristor-controlled phase shifter (TCPS)[8], unified
power flow controller (UPFC) [9] and static synchronous compensator (STATCOM) [10]. The application of
supplementary controllers for the FACTS devices which use reliable and high speed power electronic devices
can considerably improve system damping and can also improve the system voltage profile, which is
advantageous over a PSS [5]. As one of the FACTS devices, several approaches for a TCPS have been applied
to damping controller design in power system [11-18]. The TCPS provides an alternative to the conventional
PSS in suppressing power system oscillations and is of particular importance to the power system where a PSS
cannot be properly installed for reasons such as the system voltage profile, the unsuitability of the generator and
so on [12].
In this paper, the TCPS controller has been designed to damp low frequency oscillation of the power
system and to enhance power systems stability. However, the power systems have system uncertainties due to
various generating and loading conditions, variation of system parameters and system nonlinearity, etc. The
increase of these uncertainties makes the optimal control of the power system difficult. The TCPS controller
design without considering system uncertainties may fail to operate and stabilize the power system. In order to
improve the robustness of the TCPS controller against system uncertainties, this paper focuses on a robust
controller design of the TCPS using quantitative feedback theory (QFT) [19-20]. The try-and-error loop shaping
procedure in QFT design make it difficult to design the controller to satisfy all specifications. This also makes it
high order controller. In order to design a structure-specified low-order controller that satisfies all QFT bounds,
the automatic loop shaping has been performed using a genetic algorithm (GA) [21]. The dynamic characteristic
responses by means of time domain simulations have been investigated to verify the robustness of the TCPS
controller based on QFT under various operating conditions. The control characteristics of the proposed TCPS
controller have been compared with that of the simulated annealing based PSS (SA-PSS) [8] and the SA based
TCPC (SA-TCPS)[8] controller. The simulation results show that the proposed TCPS controller provided better
dynamic responses in comparison with the SA-PSS and SA-TCPS controller.
2. QFT based controller design of thyristor-controlled phase shifter for power system…..
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II. POWER SYSTEM MODEL
2.1 Generator and exciter
Fig. 1 shows the single machine infinite bus power system which has the TCPS and local load
admittance Y in a generator bus, and transmission line impedance Z [8][15]. The generator with the IEEE Type-
ST1 excitation system is modeled by four first-order nonlinear differential equations as following equations [3].
))/MD(ωPPω
dt
d
em 1 (1)
)(ωωδ
dt
d
b 1 (2)
'')/TE')ix(x(E'E
dt
d
dqdddfdq 0 (3)
AfdEtrefAfd )/TE)uv(V(KE
dt
d
(4)
where is the rotor speed, b is the synchronous speed and the rotor angle. M is inertia constant, D
is damping coefficient, 'doT is the open circuit field time constant and 'qE is internal voltage. fdE is the field
voltage, tv is terminal voltage and Eu is PSS control input.
The output electric power equation of generator is given by
qqdde ivivP (5)
where,
2/122
)( qdt vvv (6)
qqd ixv (7)
ddqq ixEv ''
(8)
G Z
Y
1:1∠-Φ Z=R+jX
Y=G+jB
Vt vbv’
TCPS
Fig. 1. Single machine infinite bus system with a TCPS
2.2 TCPS model
Fig. 2 shows the configuration of a TCPS [11][13][15]. The basic function of a TCPS is to control
transmission line power flow through the modulation of the phase angle difference between the two sides of the
transmission line voltage. The voltage at the end bus of TCPS 'v is phase shifted with respect to the input voltage
tv by angle as shown in Fig. 2[15].
The TCPS in Fig. 1 has a ratio of 1:1 . The real power flow is obtained by
)sin(
'
X
vE
P
bq
e
(9)
3. QFT based controller design of thyristor-controlled phase shifter for power system…..
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where is phase shift angle of the TCPS. The TCPS can control the relative phase angle between the system
voltage by adjusting the angle .The phase shift angle of the TCPS, , can be modeled by the first order
transfer function and can be written as following equation [8][17].
STCPSrefS )/T)u((K
dt
d
(10)
where ref is the reference angle, and ST and SK are the gain and time constant of the TCPS respectively.
V VΔ V’
BT
Vdc
α α21
V V’
VΔ
Φ
ET
t
t
Fig. 2.Configuration of TCPS
2.3 Linearized model
To design QFT based controller, the linearized model around a nominal operating point is needed. The
detail procedure is in [8]. The linearized equation to nonlinear differential equations such as (1)~(4) and (10)
including the generator, excitation system and TCPS can be expressed by
uBxAx (11)
where,
A
A
vA
AA
A
A
A
do
q
dododo
p
b
T
T
KK
TT
KK
T
KK
T
K
TT
K
T
K
M
K
M
K
M
D
M
K
A
1
0000
1
0
''
1
'
0
'
0
0000
65
34
21
,
S
S
T
K
B
0
0
0
0
[x , , 'qE , fdE , ]T
, ][ TCPSuu .
x and u are the state and control vector respectively. A and B are constant matrices which depend on system
parameters and the operating point. The parameters 61 ~ KK , pK , qK and vK are computed in operating
condition.
The block diagram of the linearized power system is shown in Fig. 3 [8][17].
4. QFT based controller design of thyristor-controlled phase shifter for power system…..
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K1
D+sM
1
s
377
KqKp Kv
K4 K5
K2
K5+sTdo ’
1
1+sTA
KA
K6
+
-
- -- -
+
-
-
-
ΔΦ
Δω Δδ
upss
ΔEfdΔEq’
Fig. 3.Block diagram of the linearized power system model
III. DESIGN OF TCPS CONTROLLER BASED ON QFT USING GA
3.1 QFT overview [19]
The basic procedure of a conventional QFT design is as follow. First step for a QFT design is to
convert the target performance specifications of the closed loop system and the system uncertainty into QFT
bounds. Then the controller )(sKTCPS is designed by using the gain-phase loop shaping technique until the
nominal open loop transfer function )()()( sKSGsL TCPSoo satisfied the QFT bounds at all selected frequency as
shown in Fig. 4. However the loop shaping method is usually performed manually. The procedure is a trial and
error method which inserts or manipulates gain, poles and zeros in the nominal open loop transfer function of
system.
Fig. 4. QFT bounds and )(0 sL
3.2 Procedure of TCPS controller design based on QFT using GA
To design the TCPS controller based on QFT, the parameter uncertainty must be selected. Then we can
get the transfer function for the uncertain plant sets )(SG G. The ranges of the active power and reactive
power in this paper are chosen as follows.
3170 .P. e , 2020 .Q. e (12)
phase
gain
B(1)
B()
B()
B()
B()
L(j)
L(j)
L(j)
L(j)
L(j)
phase
gain
B(1)
B()
B()
B()
B()
L(j)
L(j)
L(j)
L(j)
L(j)
5. QFT based controller design of thyristor-controlled phase shifter for power system…..
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After selecting the uncertain plant sets, the frequency points are selected as follows.
i = [0.1, 1, 2, 3, 4, 5, 6, 7, 8, 10, 50, 100] rad/sec (13)
The plant templates of the uncertain plant sets )( ijG are calculated at the selected all frequency points
i . And an arbitrary stable transfer function in the plant sets is chosen as the nominal plant )(sGo . And after
selecting the robust stability and disturbance attenuation specifications, QFT bounds are calculated at all
frequency points i . The robust stability and disturbance attenuation specifications are defined as follows
4.1
)(1
)(
0
0
jL
jL
(14)
011.0
)(1
)(
0
jL
jG
(15)
As the last stage for the TCPS controller design based on QFT, the loop shaping must be accomplished
until QFT bounds at all frequency are satisfied and the closed-loop nominal system is stable. However, the
manual loop shaping procedure is very difficult and takes long time. Therefore, the loop shaping procedure will
be replaced by GA. To do this, the structure of the controller )s(KTCPS has been specified as shown in Fig. 5.
1+sTS
KS
41
31
21
11
1 TCPSsT
TCPSsT
TCPSsT
TCPSsT
wsT
wsT
TCPSK
Φ
Φmax
Φmin
utcps-max
utcps-minutcps
Φref
+
-
Δω
Genetic
Algorithm
Performance
Index J
KTCPS(s)
Fig. 5. A Block diagram for selecting the TCPS controller parameters using GA
The optimized parameters using GA are TCPSK , wT , 1TCPST , 2TCPST , 3TCPST and 4TCPST as shown in Fig. 5.
In order to optimize these 6 parameters using GA, the objective function has been chosen as follows.
h
i
i_boundi
damp
J
J
OJmin
1
1 (16)
where, and ),...,3,2,1( hii are the weighting values. dampJ is the damping ratio for the dominant oscillation
mode and iboundJ _ is defined as the bound index which checks QFT bound satisfaction at i . Assuming that
the eigenvalue corresponding to the dominant oscillation mode for the closed loop system is j , the
damping ratio dampJ is given by,
22
dampJ (17)
The bound index iboundJ _ is 0 if QFT bound at i is satisfied, but 1 otherwise. The goal of this study
is to minimize the objective function given by (16). If the eigenvalue of the closed loop system has the positive
6. QFT based controller design of thyristor-controlled phase shifter for power system…..
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value, the system is unstable. Therefore the very large value is assigned to the performance index (18) by force.
The fitness function for evaluating the each string in GA is the proposed performance index J .The performance
index J used to select parameters of TCPS controller using the GA is defined as
h
i
iboundi
damp
J
J
JIndexePerformanc
1
_
1
1
(18)
IV. SIMULATION RESULTS
To select the parameters of the TCPS controller based on QFT as shown in Fig. 5, the real variable GA
using the tournament selection method, the arithmetic crossover and the uniform mutation are used. The genetic
algorithm optimization toolbox (GAOT) [21] has been used to optimize the parameters of the TCPS controller.
The population size of the GA is 200 and the generation number is 200. The parameters of the designed TCPS
controller based on QFT using GA are TCPSK = 36.6552, wT = 99.7840, 1TCPST = 132.9217, 2TCPST = 71.3789,
3TCPST = 34.4548 and 4TCPST = 19.9338.
Fig. 6 shows the loop shaping result using GA for the nominal open loop transfer function
)()()( 00 sKsGsL TCPS according to i . It is confirmed that the nominal open loop transfer function )(sLo satisfied
all QFT bounds at all selected frequency as shown in Fig. 4.
Fig. 6.QFT bounds and loop shaping result using GA
To verify the robust performance of the designed TCPS controller based on QFT using GA, the
nonlinear simulations in time domain have been performed under the 3operating conditions of the power system.
The proposed TCPS controller have been compared to those of the conventional simulated annealing based PSS
(SA-PSS)[8] and the simulated annealing based TCPS (SA-TCPS) [8].The normal load condition is 1eP (p.u.)
and 015.0eQ (p.u.), the leading PF load condition is 7.0eP (p.u.) and 2.0eQ (p.u.), and the heavy load
condition is 1.1eP [p.u.] and 4.0eQ [p.u.]. The simulation constraints are ≤ 10 , pssu ≤0.2(p.u.) and fdE
≤7.3 (p.u.). The system parameters are shown in Table. 1
7. QFT based controller design of thyristor-controlled phase shifter for power system…..
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Table 1. Power system parameters
Generator parameters M=9.26, D=0, 'doT =7.76, dx =0.973, 'dx =0.19, qx =0.55
Exciter parameters AK =50, AT =0.05
Line parameters R=-0.034, X=0.997, G=0.249, B=0.262
TCPS parameters SK =1, ST =0.05
Initial conditions 0eP =1.0, 0eQ =0.015, 0tV =1.05
4.1 Normal load condition
Table 2 shows the eigenvalues and damping ratio of closed loop with the conventional SA-PSS, SA-
TCPS and proposed TCPS respectively. The damping ratio with the proposed TCPS controller is improved in
comparison with the conventional SA-PSS controller and the SA-TCPS controller. Fig. 7 shows the simulation
results for angular velocity, rotor angle and terminal voltage with the SA-PSS, SA-TCPS and proposed TCPS
under normal load in case that a 3-phase short circuit occurs near the infinite bus at 1.0s and is cleared at 1.1s
without the power system configuration change. The first swing of angular velocity and rotor angle using the
proposed TCPS controller is smaller than that using the conventional SA-PSS and SA-TCPS. The voltage
profile is greatly improved with the SA-TCPS and proposed TCPS.
4.2Leading PF load condition
Fig. 8 shows the simulation results for angular velocity, rotor angle and terminal voltage with the SA-
PSS, SA-TCPS and proposed TCPS under leading PF load in case that a 3-phase short circuit occurs near the
infinite bus at 1.0s and is cleared at 1.1s without the power system configuration change. The first swing of
angular velocity and rotor angle using the proposed TCPS controller is smaller than that using the conventional
SA-PSS and SA-TCPS.
4.3 Heavy load condition
Fig. 9 shows the simulation results for angular velocity, rotor angle and terminal voltage with the SA-
PSS, SA-TCPS and proposed TCPS under heavy load in case that a 3-phase short circuit occurs near the infinite
bus at 1.0s and is cleared at 1.05s without the power system configuration change. The first swing of angular
velocity and rotor angle using the proposed TCPS controller is smaller than that using the conventional SA-PSS
and SA-TCPS.
Table 2. Eigenvalues and damping ratio
Eigenvalues Damping ratio
SA-PSS
-0.204, -8.439, -19.155
-2.776±5.042
-3.521±j6.406
1
0.482
0.482
SA-TCPS
-18.09, -0.209
-3.206±3.702
-6.67±j7.625
-11.171±0.917
1
0.655
0.658
0.997
Proposed TCPS
-2.768±j3.128
-9.435±j11.031
-15.788, -0.05, -0.014
0.663
0.650
1
8. QFT based controller design of thyristor-controlled phase shifter for power system…..
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(a) Angular velocity
(b) Rotor angle
(c) Terminal voltage
Fig. 7. Dynamic responses in case that a 3-phase short circuit occurs near the infinite bus for 0.1s under
normal load
9. QFT based controller design of thyristor-controlled phase shifter for power system…..
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(a) Angular velocity
(b) Rotor angle
(c) Terminal voltage
Fig. 8. Dynamic responses in case that a 3-phase short circuit occurs near the infinite bus for 0.1s under leading
PF load
10. QFT based controller design of thyristor-controlled phase shifter for power system…..
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(a) Angular velocity
(b) Rotor angle
(c) Terminal voltage
Fig. 9. Dynamic responses in case that a 3-phase short circuit occurs near the infinite bus for 0.05s
under heavy load
11. QFT based controller design of thyristor-controlled phase shifter for power system…..
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V. CONCLUSION
In this paper, the TCPS controller based on QFT using GA has been designed to enhance the power
system stability. The QFT bounds and the damping ratio as the objective function of GA to select parameters of
the TCPS controller has been used to design the robust controller. The robust performance of the proposed
TCPS controller has been compared to those of the conventional SA-PSS and SA-TCPS. The main results in
this paper are as follows.
① It is possible to automatically design the TCPS controller using the GA without a trial and error in loop
shaping procedure.
② The simulation results show that the proposed TCPS controller endows better dynamic characteristics
compared to that of conventional PSS.
③ The proposed TCPS controller can more significantly improve the voltage profile comparing with the
conventional PSS.
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