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Robustness investigation of the linear multi-variable control technique for power management of DFIG wind turbines
, Article International Journal of Advanced Mechatronic Systems ; Volume 5, Issue 1 , 2013 , Pages 37-46 ; 17568412 (ISSN) ; Banazadeh, A ; Sharif University of Technology
2013
Abstract
Variable speed wind turbines are widely used in the modern power industry. These turbines that are usually driven by doubly fed induction generators (DFIGs) contain two groups of controlling variables; mechanical variables like pitch angle and electrical variables like rotor voltage. During the turbine operation, with variable wind velocity, power must be managed in two regimes; power optimisation and power limitation. In the current research, initially a non-linear simulation, based on the general wind turbine dynamic model is presented. Then, the desired controllers for both pitch angle and generator voltage components are constructed. After designing the controller, in order to...
Fast maximum power point tracking for PV arrays under partial shaded conditions
, Article 2016 18th European Conference on Power Electronics and Applications, EPE 2016 ECCE Europe25 October 2016, Article number 7695463 ; 2016 ; 9789075815245 (ISBN) ; Parniani, M ; Zarei, S. F ; Mohammadian Foroushani, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
P-V characteristic of photovoltaic (PV) arrays under partially shaded conditions (PSC) has multiple peaks, and conventional maximum power point tracking (MPPT) algorithms may fail to track the global maximum power point (GMPP) because of their insufficient intelligence in discriminating the local and global peaks. This paper proposes a novel fast MPPT method to achieve GMPP of PV array under all PSCs. The proposed method reduces the number of required samples and increases the speed of GMPP tracking based on comprehensive study of I-V and P-V characteristics of PV array. Performance of the proposed method has been evaluated in simulations of different PSCs. Also, its performance has been...
Cost Effective and Optimum Strategy for Gride Connected Small Wind Turbine
, M.Sc. Thesis Sharif University of Technology ; Oraei, Hashem (Supervisor)
Abstract
Regarding the range of power in small wind turbine ,the manufacturing cost is very important to produce it feasible . so cost factors should be considered in control strategy. small wind turbine operate at lower wind speed because they are located where the energy is needed rather than where the wind is high for example in residential or rural area in lower height. In these condition wind speed are changing more because of lower height .so the maximum power point tracking algorithm should have a fast dynamic. In order to have lower number of device there are no sensor for wind or generator’s speed .only the voltage and current of different part of the system is measured.
here the aim...
here the aim...
Design and Implementation of a Solar Charger with Maxim Power Point Tracking Ability
, M.Sc. Thesis Sharif University of Technology ; Zolghadri, Mohammad Reza (Supervisor)
Abstract
In regard to the benefits of solar energy such as endlessness and pureness, design and implementation of a convertor for absorbing energy from solar cells is of interest. Thus, a suitable convertor with acceptable efficiency is designed to charge the batteries. In order to increase the efficiency and to decrease the electromagnetic interference, a novel method is proposed for soft switching. Due to the nonlinear behavior of solar cells and also variations of their input energy with respect to the change of solar emission and temperature, two controllers - one for maximum power point tracking from solar cells and the other to appropriately charge the 48-volt batteries - are designed....
Constrained tracking control for nonlinear systems
, Article ISA Transactions ; Volume 70 , 2017 , Pages 64-72 ; 00190578 (ISSN) ; Haeri, M ; Sharif University of Technology
Abstract
This paper proposes a tracking control strategy for nonlinear systems without needing a prior knowledge of the reference trajectory. The proposed method consists of a set of local controllers with appropriate overlaps in their stability regions and an on-line switching strategy which implements these controllers and uses some augmented intermediate controllers to ensure steering the system states to the desired set points without needing to redesign the controller for each value of set point changes. The proposed approach provides smooth transient responses despite switching among the local controllers. It should be mentioned that the stability regions of the proposed controllers could be...
Adaptive generalized predictive control of active queue management in TCP networks
, Article EUROCON 2005 - The International Conference on Computer as a Tool, Belgrade, 21 November 2005 through 24 November 2005 ; Volume I , 2005 , Pages 676-679 ; 142440049X (ISBN); 9781424400492 (ISBN) ; Haeri, M ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
This paper develops methodology and technique tor the design, analysis, and impie mentation of an adaptive generalized predictive controller (AGPC) for Active Queue Management in TCP Networks. The TCP/AQM dynamic is modeled experimentally as a second-order system with a time delay where its parameters are estimated using the standard gradient algorithm. Based on this model, an AGPC is designed to gain the set-point tracking and robustness. AGPC, as a queue-based control mechanism, responds quickly to traffic changes, thus allowing for high utilization and small loss. We illustrate our results using ns-2 simulations and demonstrate the practical impact of adaptive model reference control on...
Partial shading detection and smooth maximum power point tracking of PV arrays under PSC
, Article IEEE Transactions on Power Electronics ; Volume 31, Issue 9 , 2016 , Pages 6281-6292 ; 08858993 (ISSN) ; Mohammadian Forushani, H ; Parniani, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
One of the most important issues in the operation of a photovoltaic (PV) system is extracting maximum power from the PV array, especially in partial shading condition (PSC). Under PSC, P-V characteristic of PV arrays will have multiple peak points, only one of which is global maximum. Conventional maximum power point tracking (MPPT) methods are not able to extract maximum power in this condition. In this paper, a novel two-stage MPPT method is presented to overcome this drawback. In the first stage, a method is proposed to determine the occurrence of PSC, and in the second stage, using a new algorithm that is based on ramp change of the duty cycle and continuous sampling from the P-V...
Robustness enhancement of optical flow sensors accuracy to surface texture variations using point tracking algorithm
, Article 5th RSI International Conference on Robotics and Mechatronics, IcRoM 2017, 25 October 2017 through 27 October 2017 ; 2018 , Pages 406-410 ; 9781538657034 (ISBN) ; Vossoughi, G ; Sharif University of Technology
Abstract
Novel architecture of high precision localization using optical flow sensor (OFS) combined with Iterative Point Tracking Algorithm (IPTA) is proposed. This work focuses on attenuation of OFS' sensitivity dependency on texture of surface over which sensor is moving. The aim for the design of experimental setup is to verify how much a robustness of OFS's sensitivity on various surfaces improves. In this regard, four different surfaces' texture including iron, paper, textile and granite stone is opted. Experimental results indicate that sensor's resolution via IPTA on surfaces of iron, paper, textile and granite stone respectively equal to 382, 460, 528 and 448 CPI. Optimal value of the...
Minimizing the Error of Set Point Tracking in MIMO Plants with Broken Actuators
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
Fault occurrence is an inevitable problem in industrial plants. These faults have numerous types. Some common kinds of faults are faults in actuators, faults in system dynamics, and faults in sensors. In many cases it is not possible to change or repair the broken part immediately. On the other hand, it is not reasonable to shut-down the whole system due to a minor failure. Therefore we should take a measure to have the best output possible in a faulty plant. In this thesis we have proposed a new static compensator by which we distribute the contribution of the faulty actuator among the other ones. At the end we evaluate the method by means of simulations
Facial Expression Recognition Using Soft Computing
,
M.Sc. Thesis
Sharif University of Technology
;
Manzuri, Mohammad Taghi
(Supervisor)
Abstract
Human face-to-face communication is an ideal model for designing a multimodal/media human-computer interface (HCI). Recent advances in image analysis and pattern recognition open up the possibility of automatic detection and classification of emotional and conversational facial signals. Automating facial expression analysis could bring facial expressions into man-machine interaction as a new modality and make the interaction tighter and more efficient. In this research an accurate real-time sequence-based system for representation, recognition and analysis of low-intensity facial expressions and facial action uints (FAUs) is presented. The feature extraction is done using facial feature...
Improvement of Dynamic Modeling and Control of Single-axis Two wheeled Vehicle
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Gholamreza (Supervisor)
Abstract
In the recnt decades, traffics and airpolution are the most impoetant concerns of researchers in the field of city transportation. One of the most successful ways to overcome these poblems is to ustilize two-wheeled, one axis balancing vehicles. These vehicles occupies a small sapace, consumes less energy and its considerable maneuverability, makes it the best option to reform in-city transportation system. The newly introduced model of these robots incorporates a passenger cabin and a strick to control its movement. Unfortunately, in all of the recent studies, robots dynamics and controller system are base on optimistic hypothesis, which is no slippage between ground and wheels. Even in the...
Performance Improvement of Maximum Power Point Tracker in Grid-Connected Photovoltaic Systems
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
Increase in growing concerns over environmental pollution and depletion of fossil fuel resources motivate the need for cleaner energy technologies and stimulate research in facilitating renewable energy systems. In recent years, photovoltaic systems have attracted great attention since they remove the need for energy storage systems and intermediate processess for energy conversion. However, high capital cost, low efficiency and low energy density per area of these systems, as compared with other technologies hinder its industrial use. To surmount these bottlenecks and improve technical performance of PV systems, it is crucial to optimize configuration of convertor connection and to improve...
Comparison between backstepping and input-output linearization techniques for pH process control
, Article Journal of Process Control ; Volume 22, Issue 1 , 2012 , Pages 263-271 ; 09591524 (ISSN) ; Shahrokhi, M ; Mehrabani, A ; Sharif University of Technology
Abstract
In this work performances of adaptive backstepping controller (BSC) and globally linearizing controller (GLC) are compared for pH control. First, based on the system full order model a GLC has been designed and it has been shown that this controller is identical to BSC proposed in the literature. Next in order to avoid state estimator design, BSC and GLC are designed based on pH reduced order model and their identities have been established. Through computer simulations, it has been shown that the performance of non-adaptive GLC designed based on reduced order model is better than that of adaptive BSC designed based on pH full order model which requires state measurement for implementation....
Robust fractional-order compensation in the presence of uncertainty in a pole/zero of the plant
, Article IEEE Transactions on Control Systems Technology ; Volume 26, Issue 3 , May , 2018 , Pages 797-812 ; 10636536 (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
This paper deals with robust frequency compensation in control of fractional-order plants with an uncertain fractional pole/zero (or specially in control of integer-order plants with an uncertain pole/zero). The specifications yielding a robust compensation are introduced, and fractional-order compensators are proposed for satisfying these specifications in the set-point tracking control of the above-mentioned plants. Also, the infinite ranges for the uncertain parameter of the plant, in which satisfying robust compensation specifications is possible by the obtained compensators, are exactly specified. Furthermore, the stability of the obtained control system is analytically analyzed....
Linear multi-variable control technique for smart power management of wind turbines
, Article 2012 International Conference onAdvanced Mechatronic Systems, ICAMechS 2012 ; 2012 , Pages 559-564 ; 9780955529382 (ISBN) ; Banazadeh, A ; Sharif University of Technology
2012
Abstract
Variable speed wind turbines are widely used in the modern power industry. These turbines that are usually driven by doubly fed induction generators (DFIG) contain two groups of controlling variables; mechanical variables like pitch angle, and electrical variables like rotor voltage. During the turbine operation, with variable wind speed, power must be managed in two different regimes; power optimization and power limitation. In the current research, initially a non-linear simulation, based on the general wind turbine dynamic model is presented. Then, the desired controllers for both pitch angle and generator voltage components are constructed. To validate turbine behavior and controller...
Stability and performance analysis of a single-stage grid-connected photovoltaic system using describing function theory
, Article International Transactions on Electrical Energy Systems ; Volume 26, Issue 9 , 2016 , Pages 1898-1916 ; 20507038 (ISSN) ; Mokhtari, H ; Karimi, S ; Azizian, M. R ; Sharif University of Technology
John Wiley and Sons Ltd
Abstract
Challenging problems in the design and analysis of photovoltaic (PV) systems stem from the nonlinear current–voltage (I–V) characteristics of solar cells. This paper presents an analytical analysis based on a describing function method to investigate the transient and steady-state characteristics of a three-phase single-stage grid-connected PV system. In this study, the nonlinear I–V characteristic of the PV array is linearized around the operating point. The nonlinear dynamic of the maximum power point tracking controller is divided into two parts of continuous and discrete. For the continuous part, the common small-signal linearization is applied, while for the discontinuous part, a...
Improvement of Steady State and Dynamic Performance of Grid-connected Photovoltaic Power Generation Systems
, Ph.D. Dissertation Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
Global growth of electrical energy consumption and various limitations on the use of fossil fuels, such as environmental problems, rising prices and their limited available resources, have resulted in growing interest and investment in the usage of renewable energy generation, especially photovoltaic (PV) systems. Although the off-grid operation of PV systems was its dominant operation form in the past, proliferation of these systems has made the grid-connected operating mode widespread in recent years. However, their grid connection causes technical problems which need to be resolved. This thesis studies and analyses the steady state and dynamic operation of PV systems in grid-connected...
A robust maximum power point tracker with fully analog implementation
, Article 8th Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2017, 14 February 2017 through 16 February 2017 ; 2017 , Pages 490-495 ; 9781509057665 (ISBN) ; Rajaei, A. H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
An analog circuit for maximum power point tracking of a PV battery charger with minimum number of elements is proposed which works in a full range condition with a fixed switching frequency. In conventional MPPT algorithms which provide PV current or voltage reference value as output, fast climate changes may cause system instability. Here, a new variable is defined to eliminate the problem and improve the stability of the system. In order to compare the presented circuit with a conventional system, perturb and observe (P&O) MPPT algorithm which is well-known in PV systems is implemented on the same system. Simulation results (Conventional P&O algorithm and proposed structure) are presented...
Adaptive nonlinear control of pH neutralization processes using fuzzy approximators
, Article Control Engineering Practice ; Volume 17, Issue 11 , 2009 , Pages 1329-1337 ; 09670661 (ISSN) ; Shahrokhi, M ; Nejati, A ; Sharif University of Technology
2009
Abstract
In this paper, an adaptive control scheme, based on fuzzy logic systems, for pH control is addressed. For implementation of the proposed scheme no composition measurement is required. Stability of the closed-loop system is established and it is shown that the solution of the closed-loop system is uniformly ultimately bounded and under a certain condition, asymptotical stability is achieved. Effectiveness of the proposed controller is tested through simulation and experimental studies. Results indicate that the proposed controller has good performances in set-point tracking and load rejection and much better than that of a tuned PI controller. © 2009 Elsevier Ltd. All rights reserved
Multi-input high step-up inverter with softswitching capability, applicable in photovoltaic systems
, Article IET Power Electronics ; Volume 13, Issue 1 , 2020 , Pages 133-143 ; Tarzamni, H ; Tahami, F ; Khoun Jahan, H ; Bannae Sharifian, M. B ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
In this study, a new multi-input high step-up inverter, based on isolated soft-switching DC-DC converter blocks is proposed. Each of these blocks can provide zero-voltage and zero-current switching for its semiconductors, which improve power efficiency. The interesting feature of this DC-DC converter is using bidirectional switches to generate both positive and negative output voltage levels in each DC-DC block with an appropriate control scheme. Each DC-DC converter operates by simple pulse width modulation control through fixed frequency and has two degrees of freedom, which provide the capability of output voltage regulation or maximum power point tracking. The proposed inverter consists...