Loading...
Search for:
disturbance-rejection
0.009 seconds
Total 50 records
Voltage control of three phase inverters by using active disturbance rejection control
, Article 30th Power System Conference, PSC 2015, 23 November 2015 through 25 November 2015 ; 2017 , Pages 169-176 ; 9781509027057 (ISBN) ; Toulabi, M. R ; Ranjbar, A. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Control of three phase inverters is of paramount importance in the realm of control applications. In this regard, this paper proposes active disturbance rejection control (ADRC) scheme as a new method for voltage control of three phase inverters in UPS applications. The main advantage of ADRC refers to the fact that it is model independent. In this paper, the controller is composed of a double loop structure including an inner current loop and outer voltage loop. This structure is used in a three phase inverter in order for implementation of voltage control. To draw a comparison between ADRC and PI as the common control method, a case study has been simulated in SIMULINK. Simulation results...
Disturbance Reduction Servo Motor Controller Design and Implementation
, M.Sc. Thesis Sharif University of Technology ; Nobakhti, Amin (Supervisor)
Abstract
The servomechanisms have wide industrial application such as robotics, Computer Numerical Control (CNC) machines, automated manufacturing and solar tracking. Several methods have already been proposed for servo motor control that the most important of them are Proportional Integral Derivative (PID), H2/H--, intelligent based controllers, and model predictive control. Problem specifications and user requirements, will determine the appropriate approach in each case. The aim of this thesis is construction of a real-life camera stabilizer to be used in the motion picture industry. Effects of base movement on the performance should be decreased by choosing appropriate sensors and control...
Hardware implementation of an ADRC controller on a gimbal mechanism
, Article IEEE Transactions on Control Systems Technology ; 2017 ; 10636536 (ISSN) ; Nobakhti, A ; Sharif University of Technology
Abstract
Active disturbance rejection control (ADRC) is applied to a one-axis gimbal mechanism. The dynamic model of the system is derived and validated from mathematical modeling and practical experiments. Disturbances acting on the complete model of the gimbal mechanism are introduced via base lateral acceleration and angular motion. The ADRC is designed by utilizing an extended state observer for observing and suppressing the effects of external disturbances and internal parameter uncertainties. A PID controller is used to form a basis of comparison for set-point tracking and disturbance rejection performance. The effects of identification errors and observer bandwidth are experimentally...
Hardware implementation of an ADRC controller on a gimbal mechanism
, Article IEEE Transactions on Control Systems Technology ; Volume 26, Issue 6 , 2018 , Pages 2268-2275 ; 10636536 (ISSN) ; Nobakhti, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Active disturbance rejection control (ADRC) is applied to a one-axis gimbal mechanism. The dynamic model of the system is derived and validated from mathematical modeling and practical experiments. Disturbances acting on the complete model of the gimbal mechanism are introduced via base lateral acceleration and angular motion. The ADRC is designed by utilizing an extended state observer for observing and suppressing the effects of external disturbances and internal parameter uncertainties. A PID controller is used to form a basis of comparison for set-point tracking and disturbance rejection performance. The effects of identification errors and observer bandwidth are experimentally...
Output power control and load mitigation of a horizontal axis wind turbine with a fully coupled aeroelastic model: novel sliding mode perspective
, Article Mathematics ; Volume 10, Issue 15 , 2022 ; 22277390 (ISSN) ; Wen, J ; Golnary, F ; Zhou, L ; Sharif University of Technology
MDPI
2022
Abstract
The power control of horizontal axis wind turbines can affect significantly the vibration loads and fatigue life of the tower and the blades. In this paper, we both consider the power control and vibration load mitigation of the tower fore-aft vibration. For this purpose, at first, we developed a fully coupled model of the NREL 5MW turbine. This model considers the full aeroelastic behaviour of the blades and tower and is validated by experiment results, comparing the time history data with the FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code which is developed by NREL (National Renewable Energy Lab in the United States). In the next, novel sensorless control algorithms are...
Robust composite nonlinear feedback control for spacecraft rendezvous systems under parameter uncertainty, external disturbance, and input saturation
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; 2018 ; 09544100 (ISSN) ; Allahverdizadeh, F ; Sharifi, A ; Sharif University of Technology
SAGE Publications Ltd
2018
Abstract
This paper presents a new robust composite nonlinear feedback control law for accurate, smooth, and fast regulation in the presence of parameter uncertainties, external disturbances, and input saturation for a class of spacecraft rendezvous systems. The novel proposed method consists of the original composite nonlinear feedback part for good transient performance plus a nonlinear disturbance rejection part for reducing the steady-state error stemming from variable disturbances and simultaneously producing feasible control input. The nonlinear disturbance rejection relies on sliding-mode observer for disturbance estimation. Closed-loop system stability has been proved with the Lyapunov...
Robust composite nonlinear feedback control for spacecraft rendezvous systems under parameter uncertainty, external disturbance, and input saturation
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 234, Issue 2 , 2020 , Pages 143-155 ; Allahverdizadeh, F ; Sharifi, A ; Sharif University of Technology
SAGE Publications Ltd
2020
Abstract
This paper presents a new robust composite nonlinear feedback control law for accurate, smooth, and fast regulation in the presence of parameter uncertainties, external disturbances, and input saturation for a class of spacecraft rendezvous systems. The novel proposed method consists of the original composite nonlinear feedback part for good transient performance plus a nonlinear disturbance rejection part for reducing the steady-state error stemming from variable disturbances and simultaneously producing feasible control input. The nonlinear disturbance rejection relies on sliding-mode observer for disturbance estimation. Closed-loop system stability has been proved with the Lyapunov...
Stability and performance preserving controller order reduction via Youla parameterization and lmis
, Article 2003 10th IEEE International Conference on Electronics, Circuits and Systems, ICECS2003, Sharjah, 14 December 2003 through 17 December 2003 ; Volume 2 , 2003 , Pages 663-666 ; 0780381637 (ISBN); 9780780381636 (ISBN) ; Sadati, N ; Sharif University of Technology
2003
Abstract
This paper develops a stability and performance preserving controller order reduction method for linear time-invariant continuous-time single-input, single-output systems. In this method, the error between the complementary sensitivity functions of the nominal closed-loop system and closed-loop system using the reduced-order controller is converted to a frequency-weighted error between the Youla parameters of the full-order and reduced-order controllers and then the H∞norm of this error, subject to a set of linear matrix inequality constraints, is minimized. The main ideas of order reduction and stability preservation are contained in the constraints of the optimization problem. However,...
Fault Tolerant Control Considering Actuator Saturation and External Disturbances
, Ph.D. Dissertation Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
A control system capable of tolerating system malfunctions while maintaining an acceptable level of performance is referred as fault tolerant control system. The constraints on the amplitude of input control signals limit the domain of attraction even for linear models. Ignoring this fact may lead to an unsatisfactory performance and even closed loop instability. Designing the controller such that the domain of attraction is maximized has been an attractive topic for researchers. On the other hand, persistent disturbances always play an essential role in the real word systems. Designing the controller in a way such that the effect of such disturbances is attenuated is another challenging...
Linear active disturbance rejection control from the practical aspects
, Article IEEE/ASME Transactions on Mechatronics ; 2018 ; 10834435 (ISSN) ; Haeri, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In this paper, important issues that could come up in practice of Active Disturbance Rejection Control (ADRC) due to a common assumption and some inevitable practical restrictions are investigated. The main idea behind ADRC is modeling effects of both internal uncertainties and external disturbances as an extra state called the total disturbance which is timely estimated. In the majority of recent works, it is assumed that time derivative of total disturbance is bounded. First we prove that, beside the system characteristics, the validity of this assumption strongly depends on the tuning parameters, even in the case of simple classes of linear second order systems. Thus, one should be...
Delay compensation of demand response and adaptive disturbance rejection applied to power system frequency control
, Article IEEE Transactions on Power Systems ; Volume 35, Issue 3 , 2020 , Pages 2037-2046 ; Toulabi, M. R ; Salehi Dobakhshari, A ; Ashouri Zadeh, A ; Ranjbar, A. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
In this paper, a modified frequency control model is proposed, where the demand response (DR) control loop is added to the traditional load frequency control (LFC) model to improve the frequency regulation of the power system. One of the main obstacles for using DR in the frequency regulation is communication delay which exists in transferring data from control center to appliances. To overcome this issue, an adaptive delay compensator (ADC) is used in order to compensate the communication delay in the control loop. In this regard, a weighted combination of several vertex compensators, whose weights are updated according to the measured delay, is employed. Generating the phase lead is the...
Estimation and Control of Harmonic Disturbances Due to Mass Unbalance and Sensor Runout in Three-Pole Active Magnetic Bearing
, M.Sc. Thesis Sharif University of Technology ; Behzad, Mehdi (Supervisor) ; Manzuri, Mohammad Taghi (Co-Advisor)
Abstract
Disturbances due to sensor runout and mass unbalance are the main sources of harmonic disturbances in active magnetic bearing systems. Existence of this type of the disturbance not only causes harmonic vibrations in the system but also changes the steady-state position of the axis of rotation from the geometric center of the AMB. In this research, an observer-based control method used to estimate and reject this disturbance. Proposed integral observer estimates dc and harmonic content of the sensor runout and also estimates the states of the system at the same time with good precision. Lyapunov method is used to prove asymptotic stability of the proposed observer and demonstrated that sensor...
An integrated performance and robust stability based multi-model control of nonlinear systems: a PH neutralization reactor
, Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 679-684 ; 9781509059638 (ISBN) ; Haeri, M ; Sharif University of Technology
Abstract
This paper presents a new multi-model control scheme which integrates the stability and performance requirements to determine the nominal local models. Gap metric and stability margin concepts are applied to measure the distance between the local models and to grid the operation range of nonlinear system, respectively. The minimization of the integral of time absolute error is included as performance criterion. Furthermore, the multi-model decomposition and local controllers design are integrated in an optimization problem which provides avoidance of the redundancy issue. A fixed PI structure is considered as the local controllers to simplify the global multi-model controller structure....
Experimental investigation on the micro-step control disturbance rejection under random excitations
, Article DETC2005: ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Long Beach, CA, 24 September 2005 through 28 September 2005 ; Volume 1 B , 2005 , Pages 1747-1751 ; 0791847381 (ISBN) ; Behzad, M ; Sharif University of Technology
2005
Abstract
Effect of random signals with various powers, as current loads, on positioning and disturbance rejection problems on micro-step PID closed loop control system is addressed in this paper. Experimental results due to implementing different white noise power, speed, and a 0.3 N.m disturbance load torque show that, Random noise source changes current profile and affects the accuracy of positioning in tracking and disturbance rejection problems. Performance of the PID proposed controller under the implementation of random noise on phases of the HSM has been proved to be accurate enough even under disturbance torque acting on the system. Copyright © 2005 by ASME
Harmonic disturbance attenuation in a three-pole active magnetic bearing test rig using a modified notch filter
, Article JVC/Journal of Vibration and Control ; Volume 23, Issue 5 , 2017 , Pages 770-781 ; 10775463 (ISSN) ; Behzad, M ; Salarieh, H ; Mehdigholi, H ; Sharif University of Technology
Abstract
This study is concerned with the problem of harmonic disturbance rejection in active magnetic bearing systems. A modified notch filter is presented to identify both constant and harmonic disturbances caused by sensor runout and mass unbalance. The proposed method can attenuate harmonic displacement and currents at the synchronous frequency and its integer multiples. The reduction of stability is a common problem in adaptive techniques because they alter the original closed-loop system. The main advantage of the proposed method is that it is possible to determine the stability margins of the system by few parameters. The negative phase shift of the modified notch filter can be tuned to...
Operational Analysis of a Photovoltaiec Plant as a Micorgird
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
Nowadays, high reliability requirements for commercial and industrial loads, make it necessary to install microgrids for supplying the loads during power outages. Due to the fact that solar energy is clean, free of noise pullotion and also it benefits from the governmental obligations, it is a wealthy choice for supplying the load in microgrid. Designing and operation of the photovoltaic microgrid are the two important steps that should be considered. In this thesis, these two steps have been investigated by integrating a battery system into a solar PV plant and control of PV mictrorid in islanded mode. In the designing step, the optimum battery bank is calculated. For calculating the...
A comparison between the minimum-order & full-order observers in robust control of the air handling units in the presence of uncertainty
, Article Energy and Buildings ; Volume 91 , 15 March , 2015 , Pages 115-130 ; ISSN: 3787788 ; Moradi, H ; Alasty, A ; Sharif University of Technology
Abstract
Control of the air-handling units (AHU) is required to maintain satisfactory comfort conditions with low energy consumption. In the case of failure in sensor fusion systems of AHUs, full-order observers can be used as the supportive tool to provide an acceptable estimation of state variables. In this paper, a multivariable nonlinear model of the AHU is considered in the presence of uncertainties. The indoor temperature and relative humidity are controlled via manipulation of valve positions of air and cold water flow rates. In proposed hybrid control system, full and minimum-order observers are designed for the estimation of indoor temperature and relative humidity. Also, a regulator for...
Optimal LQR-based multi-loop linear control strategy for UPS inverter applications using resonant controller
, Article Proceedings of the IEEE Conference on Decision and Control, 12 December 2011 through 15 December 2011, Orlando, FL ; 2011 , Pages 3080-3085 ; 01912216 (ISSN) ; 9781612848006 (ISBN) ; Edrington, C. S ; Maghsoudlou, B ; Mokhtari, H ; Sharif University of Technology
2011
Abstract
This paper presents an optimal multi-loop control structure for uninterruptible power supply (UPS) applications which use voltage source inverter (VSI) coupled with LC filter. A resonant controller ensures tracking of sinusoidal voltage reference and rejection of sinusoidal current disturbance with no steady-state error if the loop remains stable. The challenges are reduction of output total harmonic distortion (THD), improving damping of the LC resonance frequency and preventing generation of fast closed-loop modes which go beyond the frequency range of inverter with limited switching frequency. An extension of the classic linear quadratic regulator (LQR) is proposed which addresses the...
Multivariable robust adaptive sliding mode control of an industrial boiler-turbine in the presence of modeling imprecisions and external disturbances: A comparison with type-I servo controller
, Article ISA Transactions ; Volume 58 , September , 2015 , Pages 398-408 ; 00190578 (ISSN) ; Moradi, H ; Vossoughi, G ; Sharif University of Technology
ISA - Instrumentation, Systems, and Automation Society
2015
Abstract
To guarantee the safety and efficient performance of the power plant, a robust controller for the boiler-turbine unit is needed. In this paper, a robust adaptive sliding mode controller (RASMC) is proposed to control a nonlinear multi-input multi-output (MIMO) model of industrial boiler-turbine unit, in the presence of unknown bounded uncertainties and external disturbances. To overcome the coupled nonlinearities and investigate the zero dynamics, input-output linearization is performed, and then the new decoupled inputs are derived. To tackle the uncertainties and external disturbances, appropriate adaption laws are introduced. For constructing the RASMC, suitable sliding surface is...
Robust backstepping control of an interlink converter in a hybrid AC/DC microgrid based on feedback linearisation method
, Article International Journal of Control ; 2016 , Pages 1-15 ; 00207179 (ISSN) ; Sadati, N ; Hamzeh, M ; Sharif University of Technology
Taylor and Francis Ltd
Abstract
This paper presents a robust dc-link voltage as well as a current control strategy for a bidirectional interlink converter (BIC) in a hybrid ac/dc microgrid. To enhance the dc-bus voltage control, conventional methods strive to measure and feedforward the load or source power in the dc-bus control scheme. However, the conventional feedforward-based approaches require remote measurement with communications. Moreover, conventional methods suffer from stability and performance issues, mainly due to the use of the small-signal-based control design method. To overcome these issues, in this paper, the power from DG units of the dc subgrid imposed on the BIC is considered an unmeasurable...