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Design and assessment of variable-structure LQG PID multivariable controllers
, Article Optimal Control Applications and Methods ; 2016 ; 01432087 (ISSN) ; Nobakhti, A ; Sharif University of Technology
John Wiley and Sons Ltd
2016
Abstract
Control Performance Assessment (CPA) and tuning of PID controllers are studied in this paper. We propose a framework for systematic analysis of the tradeoff between the structural complexity of the controller and its performance. As the measure of the controller performance, an LQG based index is used. The problem is augmented with an additional term which forces sparsity on the complexity of a decentralized PID controller. The desired complexity is controlled via a weighting parameter which determines the cost of each additional element (i.e., P, I, and D terms). The result is a decentralized multivariable PID controller in which the complexity of each loop controller is optimized such that...
Design and assessment of variable-structure LQG PID multivariable controllers
, Article Optimal Control Applications and Methods ; Volume 38, Issue 4 , 2017 , Pages 634-652 ; 01432087 (ISSN) ; Nobakhti, A ; Sharif University of Technology
John Wiley and Sons Ltd
2017
Abstract
Control Performance Assessment (CPA) and tuning of PID controllers are studied in this paper. We propose a framework for systematic analysis of the tradeoff between the structural complexity of the controller and its performance. As the measure of the controller performance, an LQG based index is used. The problem is augmented with an additional term which forces sparsity on the complexity of a decentralized PID controller. The desired complexity is controlled via a weighting parameter which determines the cost of each additional element (i.e., P, I, and D terms). The result is a decentralized multivariable PID controller in which the complexity of each loop controller is optimized such that...
Decentralized multivariable PID controller with pre compensator for gas turbine system
, Article 2017 IEEE 4th International Conference on Knowledge-Based Engineering and Innovation, KBEI 2017 ; Volume 2018-January , 2018 , Pages 0074-0082 ; 9781538626405 (ISBN) ; Azizi, A ; Nourisola, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In this paper, a restricted structure of PID controller is proposed for automobile gas turbine by considering a LQG cost function. So PID Controller coefficients are calculated by minimizing this cost function. One of the most important characteristics of this approach, its ability to design various structure PID controllers by solving optimization problem only for one time, moreover it can approximate main optimization problem by a repetitive Quadratic optimization Problem (QP). This approach is convex optimization and has an analytic solution; therefore its calculations are not complicated. In defined cost function, there are two weighting functions, control error and control action; they...
Robust control of the variable speed wind turbines in the presence of uncertainties: A comparison between H∞ and PID controllers
, Article Energy ; Volume 90 , October , 2015 , Pages 1508-1521 ; 03605442 (ISSN) ; Vossoughi, G ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
To achieve a cost-effective and reliable use of wind power generation, advanced control techniques are required. In this paper, the application of two control strategies for the improvement of wind turbine power output is investigated in the presence of model/environmental uncertainties. Rotational speed of the wind turbine and consequently its power output are controlled via manipulation of blades pitch angle (at a constant generator torque). First, the classical PID controller is designed based on root locus analysis while in the second scheme, an H∞-robust controller is designed via μ-synthesis based on DKiteration algorithm. Performance of the two controllers in tracking of the desired...
Robust non-fragile fractional order PID controller for linear time invariant fractional delay systems
, Article Journal of Process Control ; Vol. 24, issue. 9 , 2014 , pp. 1489-1494 ; Haeri, M ; Sharif University of Technology
Abstract
A fractional order PID controller is designed to stabilize fractional delay systems with commensurate orders and multiple commensurate delays, where the time delays in the system may belong to several distinct intervals. Moreover, the controller parameters should belong to given intervals. In order to stabilize the system, the D-subdivision method is employed to choose the stabilizing set of the controller parameters from their available values. Furthermore, the nearest values of the obtained stabilizing set to their mean values are selected as the controller parameters so that a non-fragile controller is concluded. Two numerical examples evaluate the proposed control design method
Harmonic effects optimization at a system level using a harmonic power flow controller
, Article Turkish Journal of Electrical Engineering and Computer Sciences ; Volume 28, Issue 5 , 2020 , Pages 2586-2601 ; Mokhtari, H ; Sharif University of Technology
Turkiye Klinikleri
2020
Abstract
Increase of nonlinear loads in industries has resulted in high levels of harmonic currents and consequently harmonic voltages in power networks. Harmonics have several negative effects such as higher energy losses and equipment life reduction. To reduce the levels of harmonics in power networks, different methods of harmonic suppression have been employed. The basic idea in all of these methods is to prevent harmonics from flowing into a power network at customer sides and the point of common coupling (PCC). Due to the costs, none of the existing mitigating methods result in a harmonic-free power system. The remaining harmonic currents, which rotate in a power network according to the system...
A PID controller design to suppress chatter vibrations in the turning process studying its effect in nonlinear delayed process
, Article 10th International Conference on Modern Circuits and Systems Technologies, MOCAST 2021, 5 July 2021 through 7 July 2021 ; 2021 ; 9781665418478 (ISBN) ; Moradi, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
High-quality, high-production-rate machining operations are significantly hindered by the regenerative chatter. Therefore, chatter suppression is of great significance; and active control is one of the best ways to curb it. In this paper, the orthogonal turning process is modeled as a single-degree-of-freedom system that includes the effect of tool wear; and described through a delay differential equation (DDE). Based on the model, stability lobes diagrams are obtained by the trial and error. The actuator force is the input for the control system and the tool vibration is the output. A classical PID controller is designed to improve the stability of the process and curb the self-excited...
Modeling and control of dissolved oxygen concentration in the fermentation of glucose to gluconic acid
, Article Periodica Polytechnica: Chemical Engineering ; Volume 57, Issue 1-2 , 2013 , Pages 63-70 ; 03245853 (ISSN) ; Bamdad, H ; Papari, S ; Yaghmaei, S ; Sharif University of Technology
2013
Abstract
Fermentation systems are often highly nonlinear, with poorly understood dynamic behaviour of the reactor. In this work, mathematical modeling of the fermentation process based on aeration rate control was performed in a semi-batch airlift loop bioreactor. The bioconversion of glucose to gluconic acid by the Aspergillus niger strain was considered in an oxygen consuming system in the liquid phase. The proper kinetic model for the bioconversion of glucose to gluconic acid was investigated using experimental data from a 40 dm3reactor. Kinetic parameter estimation was used from the literature. The model was validated by experimental data and was compared with the Monod kinetic model. The...
A distortion-free phase-locked loop system for FACTS and power electronic controllers
, Article Electric Power Systems Research ; Volume 77, Issue 8 , 2007 , Pages 1095-1100 ; 03787796 (ISSN) ; Sharif University of Technology
2007
Abstract
This paper presents a single-phase phase-locked loop (PLL) system which is primarily free from the double-frequency ripples from which the conventional PLL system suffers. The proposed PLL is then extended to reject the harmonic components from the input signal and to estimate the phase-angle and frequency of the distorted input signal with no error. Three units of the proposed PLL can be used in three-phase power systems, such as FACTS and HVDC converters, to estimate the phase-angles of the individual phases with no double-frequency ripples and without sensitivity to the presence of harmonics and inter-harmonics. This makes the proposed PLL unique and desirable for applications which...
AQM controller design for TCP networks based on a new control strategy
, Article Telecommunication Systems ; Volume 57, Issue 4 , December , 2013 , Pages 295-311 ; 10184864 (ISSN) ; Jahangir, A. H ; Ebrahimi, B ; Sharif University of Technology
Kluwer Academic Publishers
2013
Abstract
When the network suffers from congestion, the core or edge routers signal the incidence of congestion through the active queue management (AQM) to the sources. The time-varying nature of the network dynamics and the complex process of retuning the current AQM algorithms for different operating points necessitate the development of a new AQM algorithm. Since the non-minimum phase characteristics of the network dynamics restrict direct application of the proportional-integral-derivative (PID) controller, we propose a compensated PID controller based on a new control strategy addressing the phase-lag and restrictions caused by the delay. Based on the unstable internal dynamics caused by the...
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...
Battery energy storage systems and demand response applied to power system frequency control
, Article International Journal of Electrical Power and Energy Systems ; Volume 136 , 2022 ; 01420615 (ISSN) ; Toulabi, M ; Ashouri Zadeh, A ; Ranjbar, A. M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In this paper, several new control strategies for employing the battery energy storage systems (BESSs) and demand response (DR) in the load frequency control (LFC) task are proposed. In this way, first, the unit commitment problem considering the BESSs’ constraints in presence of wind farms and responsive loads is solved and the best location and the optimal size of the BESSs as well as the regulation power of the responsive loads are obtained. A rule-based plan is then suggested to improve the frequency regulation considering participation of wind farms. This plan is takes into account different states associated with power system frequency response as well as BESSs’ state of charge (SOC)....
Modeling and active control of chatter vibrations of piezoelectric stacked machining arm in micro-turning process
, Article Meccanica ; Volume 55, Issue 9 , 18 July , 2020 , Pages 1707-1731 ; Moradi, H ; Movahhedy, M. R ; Sharif University of Technology
Springer
2020
Abstract
Self-excited vibrations known as chatter are considered as the most detrimental issue in micro-turning processes. Occurring unpredictably, they adversely affect the tool life, productivity rate and surface quality of the machining processes. In this paper, a novel machining arm is modeled as a piezoelectric stacked rod which is subjected to a chatter force in the orthogonal micro-turning process. Due to the fact that machining processes are affected by various sources of uncertainties, H∞ robust control approach is used to suppress the chatter vibrations of the machining arm in the presence of tool wear and dynamic model parameter variations. Also, input control force of the system is...
Locating and parameters setting of unified power flow controller for congestion management and improving the voltage profile
, Article Asia-Pacific Power and Energy Engineering Conference, APPEEC, 28 March 2010 through 31 March 2010 ; March , 2010 ; 21574839 (ISSN) ; 9781424448135 (ISBN) ; Ehsan, M ; Sharif University of Technology
2010
Abstract
This paper propose a particle swarm optimization based algorithm for locating Unified power flow controller (UPFC), as well as set its parameters, with static point of view in deregulated electricity markets in order to reduce generation cost, voltage violation and manage congestion. The modeling of UPFC has been adapted based on power injection method. In order to verify and validate the effectiveness of the proposed method, it was applied to 24-bus Reliability Test System (RTS) and the results have been discussed
Load frequency control (LFC) strategies in renewable energy‐based hybrid power systems: a review
, Article Energies ; Volume 15, Issue 10 , 2022 ; 19961073 (ISSN) ; Iqbal, M ; Shahzad, S ; Muqeet, H. A ; Shahzad, M ; Hussain, M. M ; Sharif University of Technology
MDPI
2022
Abstract
The hybrid power system is a combination of renewable energy power plants and conventional energy power plants. This integration causes power quality issues including poor settling times and higher transient contents. The main issue of such interconnection is the frequency variations caused in the hybrid power system. Load Frequency Controller (LFC) design ensures the reliable and efficient operation of the power system. The main function of LFC is to maintain the system frequency within safe limits, hence keeping power at a specific range. An LFC should be supported with modern and intelligent control structures for providing the adequate power to the system. This paper presents a...
Comment on “Design of PID controllers for interval plants with time delay”
, Article Journal of Process Control ; Volume 44 , 2016 , Pages 160-161 ; 09591524 (ISSN) ; Nobakhti, A ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In [1] three theorems are presented which relate to the problem of stabilizing PID controller design for interval time-delay plants. We present a counterexample for these results
Load-frequency control of interconnected power system using emotional learning-based intelligent controller
, Article International Journal of Electrical Power and Energy Systems ; Volume 36, Issue 1 , March , 2012 , Pages 76-83 ; 01420615 (ISSN) ; Boroushaki, M ; Hosseini, S. H ; Sharif University of Technology
2012
Abstract
In this paper a novel approach based on the emotional learning is proposed for improving the load-frequency control (LFC) system of a two-area interconnected power system with the consideration of generation rate constraint (GRC). The controller includes a neuro-fuzzy system with power error and its derivative as inputs. A fuzzy critic evaluates the present situation, and provides the emotional signal (stress). The controller modifies its characteristics so that the critic's stress is reduced. The convergence and performance of the proposed controller, both in presence and absence of GRC, are compared with those of proportional integral (PI), fuzzy logic (FL), and hybrid neuro-fuzzy (HNF)...
Investigation of switching time and pressure head effects on hydro magnetic micro-pump and flow controller
, Article 2008 Proceedings of the ASME Fluids Engineering Division Summer Conference, FEDSM 2008, 10 August 2008 through 14 August 2008, Jacksonville, FL ; Volume 2 , 2009 , Pages 463-470 ; 9780791848418 (ISBN) ; Shafii, M. B ; Fluids Engineering Division, ASME ; Sharif University of Technology
2009
Abstract
The significant importance of micro-scaled devices in medicine, lab-on-a-chip, and etc resulted in a vast variety of researches. The idea behind the novel hydro magnetic micro-pump and flow controller is that ferromagnetic particles, mixed and dispersed in a carrier fluid, can be accumulated and retained at specific sites to form pistons in a micro-tube using some external magnetic field sources along the micro-tube. This external magnetic field is related to some solenoids, which are turned on and off alternatively. Depending upon dragging speed of these pistons, which itself is a function of switching time, this device can be used to either increase (pumping) or decrease (valving) the flow...
Hydromagnetic micropump and flow controller. part a: experiments with nickel particles added to the water
, Article Experimental Thermal and Fluid Science ; Volume 33, Issue 6 , 2009 , Pages 1021-1028 ; 08941777 (ISSN) ; Shafii, M. B ; Alavi Dehkordi, E ; Sharif University of Technology
2009
Abstract
The novel idea of the Hydromagnetic Micropump and Flow Controller (HMFC) is used in this paper to construct a laboratory setup capable of bidirectional pumping and controlling the flow in microtubes. A laboratory setup, which contains no moving parts, is integrated with a pressure-driven flow setup to make the presented HMFC device. The device operation is based on controllable motion of magnetic particles, added to the carrier fluid, caused by the magnetic field, produced by solenoids located just next to the microtube. The magnitude of these forces is proportional to the strength and gradient of magnetic field which, in turn, is related to the electrical current and arrangement of the...
Location of unified power flow controller and its parameters setting for congestion management in pool market model using genetic algorithm
, Article 2006 International Conference on Power Electronics, Drives and Energy Systems, PEDES '06, New Delhi, 12 December 2006 through 15 December 2006 ; 2006 ; 078039772X (ISBN); 9780780397729 (ISBN) ; Ehsan, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
2006
Abstract
In this paper, AC Optimal Power Flow combined with UPFC has been used to manage the congestion of transmission lines in a restructured power system with pool market model. The modeling of Unified Power Flow Controller (UPFC) has been adopted based on bipolar model and power injection method. To determine an appropriate location for UPFC as well as to set its parameters, an approach based on genetic algorithm has been suggested. The modified IEEE 14-bus system is used to determine the effectiveness and applicability of the proposed method and results are discussed. ©2006 IEEE