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Evaluation of UPFC impacts on power system reliability
, Article Transmission and Distribution Exposition Conference: 2008 IEEE PES Powering Toward the Future, PIMS 2008, Chicago, IL, 21 April 2008 through 24 April 2008 ; May , 2008 ; 9781424419036 (ISBN) ; Fotuhi Firuzabad, M ; Feuillet, R ; Sharif University of Technology
2008
Abstract
This paper evaluates the reliability impact of UPFC application in power system. The paper proposes a new reliability model for the UPFC which is capable of considering different operating states of UPFC. The model is then applied to a test system to study the reliability impacts of UPFC. The impacts of operating points of different states of the model on the system reliability are analyzed. The role of model parameters in reliability impacts of UPFC is analyzed through the sensitivity analysis. A comparative study is finally conducted to illustrate the applicability of the proposed model compare to that of existing UPFC reliability models. The abilities and deficiencies of the proposed...
Power flow control and solutions with dynamic flow controller
, Article 2008 IEEE Electrical Power and Energy Conference - Energy Innovation, Vancouver, BC, 6 October 2008 through 7 October 2008 ; 2008 ; 9781424428953 (ISBN) ; Sheykholeslami, A ; Nabavi Niaki, A ; Ghaffari, H ; Sharif University of Technology
2008
Abstract
this paper presents two new methods for power flow calculation of power systems in presence of Dynamic Flow Controller (DFC), which is a new member of FACTS controllers. In first method A new steady state model of DFC is introduced for the implementation of the device in the conventional Newton-Raphson power flow algorithm. The impact of DFC on power flow is accommodated by adding new entries and modifying some existing ones in the linearized Jacobian equations of the same system without DFC. The focus of second method is on the discrete nature of the DFC and including its effects on power flow. This method is based on Nabavi model for FACTS devices. A case study on a power system located in...
Experimental investigation of the effect of active flow control on the wake of a wind turbine blade
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 235, Issue 22 , 2021 , Pages 6122-6138 ; 09544062 (ISSN) ; Davari, A. R ; Soltani, M. R ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
An extensive experimental investigation was conducted to study the effects of Dielectric Barrier Discharge (DBD), on the flow field of an airfoil at low Reynolds number. The DBD was mounted near the leading edge of a section of a wind turbine blade. It is believed that DBD can postpone the separation point on the airfoil by injecting momentum to the flow. The effects of steady actuations on the velocity profiles in the wake region have been investigated. The tests were performed at α = 4 to 36 degrees i.e. from low to deep stall angles of attack regions. Both surface pressure distribution and wake profile show remarkable improvement at high angles of attack, beyond the static stall angle of...
Probabilistic ATC Assessment Incorporating UPEC
, Ph.D. Dissertation Sharif University of Technology ; Fotuhi-Firouzabad, Mahmud (Supervisor) ; Shahidehpour, Mohammad (Co-Advisor)
Abstract
Available Transmission Capability (ATC) is a measure of remaining capability in the transmission system for future use which is calculated and posted by Independent System Operator (ISO) considering various certain and uncertain power system parameters. ATC can be affected considerably by application of flexible AC transmission system (FACTS) controller among them Unified Power Flow Controller (UPFC) is the most recent one applied in power systems. This thesis is aimed to study the probabilistic ATC assessment incorporating UPFC. It first proposes a probabilistic ATC calculation method which is capable of considering various certain and uncertain parameters of ATC calculation in the...
Cross-Layer Design Based on Inter-Session Network Coding
,
M.Sc. Thesis
Sharif University of Technology
;
Golestani, Jamaloddin
(Supervisor)
Abstract
Network coding as an efficient approach for performance improvement of communication networks has been introduced by Ahlswede et al. Despite simple forwarding schemes, in network coding scenarios, intermediate nodes forward the encoded version of their received packets. In wireless Networks, resource allocation includes routing, network coding, flow control, scheduling and power control.In this dissertation a joint scheduling, routing, flow control and Inter-session NC formulation based on a convex optimization problem is studied. Our formulation integrates the optimal scheduling, flow control and Inter-session network coding with a modified version of minimum delay routing. We propose a way...
Locating and Parameters Setting of Unified Power Flow Controller for Congestion Management
, M.Sc. Thesis Sharif University of Technology ; Ehsan, Mehdi (Supervisor)
Abstract
The competition between producers and the contracts issues between the producers and consumers of electrical energy in restructured power systems might cause on unwanted increase in power interchange beyond transmission lines capacity. If the power interchange is not well-managed, it would often cause overloads in specific path. This phenomenon is termed as lines congestion. The major goal of congestion management is to create a set of rules that ensure sufficient control over producers and consumers to maintain an acceptable level of power system security and reliability in the time of limitation of transmission network with maximizing economic market efficiency. As FACTS devices provide...
Numerical Analysis of Drop Motion over a Flat Solid Surface Due to Surface Acoustic Waves, Using Lattice Boltzmann Method
, M.Sc. Thesis Sharif University of Technology ; Mohammad Taiebi Rahni (Supervisor) ; Shams Taleghani, Arash (Co-Supervisor)
Abstract
In recent years, there have been a tremendous research performed in the field of sestems containing small scales. However, besides all advantages of such systems, microfluidic systems have extraordinary difficulties and pumping liquid drops as part of some of these systems has been very important issue. An approach related to flow control is use of surface acoustic waves (SAW), which is known as acoustofluidic device. So far, most researches have only qualitatively investigated acoustic flux phenomenon. On the other hand, computational research is ongoing more emphasizing on accuracy, optimization, and obtaining more detailed physical understanding of SAW applications. Investigation of the...
Aerodynamic Optimization of Axial Transonic Compressor Blade by Adjoint Method Using Bump/ Local Blowing
, Ph.D. Dissertation Sharif University of Technology ; Mazaheri, Karim (Supervisor)
Abstract
Transonic flow compressors are widely used today. In these systems, the occurrence of shock waves, interaction of the shock and the boundary layer, thickening of the boundary layer and separation are some challenges which can severely affect the aerodynamic performance. Here we use a numerical analysis and an optimization algorithm to optimize the aerodynamic shape of a transonic axial compressor blade section. The total pressure loss through a cascade of blade sections is selected as the cost function. A continuous adjoint optimization method is used along with a RANS solver to find the new blade section shape. Application of three different geometric modelling of a compressor blade section...
Development of Smart Charger in Standalone Solar Inverter
,
M.Sc. Thesis
Sharif University of Technology
;
Rajabi Qahnuyeh, Abbas
(Supervisor)
Abstract
The advantages of using solar energy, including absence of environmental pollution, renewability, availability, ease of installation and use, and has attracted much attention of researchers. Expanding the use of solar energy in remote areas where national grid coverage is weak, makes off-grid inverter vital role clear. The swinging nature of solar energy requires the use of electrical energy storage and battery charger for optimum energy extraction in a technically and economically manner. The aim of this project is to develop a Smart Charger in Standalone Solar Inverter. Charger circuit design has been done in order to accommodate a 4kW inverter. Selected Charger topology is the...
Biogeography-based optimization of makespan and reliability in grid computing systems
, Article International Congress on Ultra Modern Telecommunications and Control Systems and Workshops, 3 October 2012 through 5 October 2012 ; October , 2012 , Pages 336-342 ; 21570221 (ISSN) ; 9781467320153 (ISBN) ; Entezari Maleki, R ; Movaghar, A ; Sharif University of Technology
2012
Abstract
The aim of this paper is to propose a scheduling method to consider reliability along with makespan in grid computing systems. The reliability of task execution is considered in the proposed method to increase the chance of running large-scale and computationally intensive workflows successfully. To handle situations in which a resource failure in a possible scheduling solution occurs, the proposed method finds a collection of scheduling solutions instead of only one solution to run the workflow. It leads to have chance to run an alternative scheduling solution that is not using the failed resource. To find the most optimized scheduling solutions, we exploit the lately developed...
Introducing an adaptive robust controller for artificial heart
, Article Proceedings of the IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics, 24 June 2012 through 27 June 2012 ; June , 2012 , Pages 413-418 ; 21551774 (ISSN) ; 9781457711992 (ISBN) ; Jahed, M ; Sharif University of Technology
2012
Abstract
Prolonged and uncontrolled high shear stresses and turbulence can cause hemolysis, while alternating and low-level stresses may contribute to platelet activation and thrombus formation. Such deficiencies are reported for Total Artificial Heart (TAH) systems which are generally not fully capable of dynamic adaptation to sudden pressure and volume changes. This study introduces an adaptive robust controller for a linear motor based TAH (LMTAH) which overcomes such shortcomings. Proposed controller performance is compared with simulated natural heart in normal and stressed physiological conditions. Application of adaptive robust control results in flows with less stress variation and...
Simulation and experimental validation of flow-current characteristic of a sample hydraulic servo valve
, Article Scientia Iranica ; Volume 17, Issue 5 B , 2010 , Pages 327-336 ; 10263098 (ISSN) ; Seifi, R ; Saadat Foumani, M ; Sharif University of Technology
2010
Abstract
This paper presents a novel model to simulate the flow-current characteristic curve of an electro-hydraulic servo valve in steady state condition. This characteristic curve has three major zones: dead zone, linear zone and saturation zone. By using the presented approach, we can simulate the behavior of all types of valves including under lapped, critical center (zero lapped) and over lapped valves. A hydraulic tester has been designed and constructed for validation of the results. It can test the performance of flow-current and some other properties of the valve. Comparison of experimental and simulated curves describes that the model has an acceptable accuracy in determining the four...
A low-overhead and reliable switch architecture for Network-on-Chips
, Article Integration, the VLSI Journal ; Volume 43, Issue 3 , June , 2010 , Pages 268-278 ; 01679260 (ISSN) ; Miremadi, S. G ; Fazeli, M ; Sharif University of Technology
2010
Abstract
This paper proposes and evaluates Low-overhead, Reliable Switch (LRS) architecture to enhance the reliability of Network-on-Chips (NoCs). The proposed switch architecture exploits information and hardware redundancies to eliminate retransmission of faulty flits. The LRS architecture creates a redundant copy of each newly received flit and stores the redundant flit in a duplicated flit buffer that is associated with the incoming channel of the flit. Flit buffers in the LRS are equipped with information redundancy to detect probable bit flip errors. When an error is detected in a flit buffer, its duplicated buffer is used to recover the correct value of the flit. In this way, the propagation...
Separation control using quasi-radial wall jets
, Article Aerospace Science and Technology ; Volume 68 , 2017 , Pages 240-251 ; 12709638 (ISSN) ; Hajipour, M ; Sharif University of Technology
Elsevier Masson SAS
2017
Abstract
In this paper, flow separation control over a NACA 4415 wing section using arrays of discrete quasi-radial wall jets is numerically investigated. This novel flow control method is studied under conditions which the wing section angle of attack is α=18 degrees and Reynolds number based on chord length is Rec=550000. Contours of mean streamwise velocity indicated that quasi-radial wall jets cover wing surface rapidly. Therefore, arranging them in a spanwise row can be an effective way in adding momentum to the near wall fluid particles. According to the results, if blowing parameters of the jets be chosen correctly, arrays of quasi-radial wall jets would lead to considerable decrease in wake...
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...
Simulation of compressible and incompressible flows through planar and axisymmetric abrupt expansions
, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 141, Issue 11 , 2019 ; 00982202 (ISSN) ; Shafiei Ghazani, A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2019
Abstract
In this paper, compressible and incompressible flows through planar and axisymmetric sudden expansion channels are investigated numerically. Both laminar and turbulent flows are taken into consideration. Proper preconditioning in conjunction with a second-order accurate advection upstream splitting method (AUSM+-up) is employed. General equations for the loss coefficient and pressure ratio as a function of expansion ratio, Reynolds number, and the inlet Mach number are obtained. It is found that the reattachment length increases by increasing the Reynolds number. Changing the flow regime to turbulent results in a decreased reattachment length. Reattachment length increases slightly with a...
Micro-plasma actuator mechanisms in interaction with fluid flow for wind energy applications: Physical parameters
, Article Physics of Fluids ; Volume 32, Issue 7 , 2020 ; Mazaheri, K ; Sharif University of Technology
American Institute of Physics Inc
2020
Abstract
Plasma actuator is a flow control device to improve the aerodynamic performance of wind turbine blades at low airspeeds. One of the most robust numerical models for simulation of plasma actuator interaction with the fluid flow is the electrostatic model. This model is improved recently and is extensively verified by the authors. Due to the high cost of performing experimental optimizations, the optimized geometrical dimensions and materials of a plasma actuator may be sought by this numerical model. The aim of the present study is the aerodynamic enhancement of a DU21 wind turbine blade airfoil in which the effect of geometric parameters and the dielectric material is examined separately....
FEDC: Control flow error detection and correction for embedded systems without program interruption
, Article ARES 2008 - 3rd International Conference on Availability, Security, and Reliability, Proceedings, 4 March 2008 through 7 March 2008, Barcelona ; 2008 , Pages 33-38 ; 9780769531021 (ISBN) ; Fazeli, M ; Miremadi, S. G ; Sharif University of Technology
2008
Abstract
This paper proposes a new technique called CFEDC to detect and correct control flow errors (CFEs) without program interruption. The proposed technique is based on the modification of application software and minor changes in the underlying hardware. To demonstrate the effectiveness of CFEDC, it has been implemented on an OpenRISC 1200 as a case study. Analytical results for three workload programs show that this technique detects all CFEs and corrects on average about 81.6% of CFEs. These figures are achieved with zero error detection /correction latency. According to the experimental results, the overheads are generally low as compared to other techniques; the performance overhead and the...
Vorticity-based coarse grid generation for upscaling two-phase displacements in porous media
, Article Journal of Petroleum Science and Engineering ; Volume 59, Issue 3-4 , 2007 , Pages 271-288 ; 09204105 (ISSN) ; Firoozabadi, B ; Mahani, H ; Khoozan, D ; Sharif University of Technology
2007
Abstract
Coarse grid generation from finely gridded geological model is a main step in reservoir simulation. Coarse grid generation algorithms aim at optimizing size, number and location of the grid blocks by identifying the important geological and flow features which control flow in porous media. By optimizing coarse grid structure we can improve accuracy of the coarse scale simulation results to reproduce fine grid behavior. A number of techniques have been proposed in the literature. We present a novel coarse grid generation procedure based on vorticity preservation between fine and coarse grids. In the procedure, the coarse grid mesh tries to capture variations in both permeability and fluid...
Extended reliability model of a unified power flow controller
, Article IET Generation, Transmission and Distribution ; Volume 1, Issue 6 , 2007 , Pages 896-903 ; 17518687 (ISSN) ; Fotuhi Firuzabad, M ; Billinton, R ; Sharif University of Technology
2007
Abstract
One of the most important aspects in evaluating system reliability is to have a complete understanding of the engineering implications of the system and its associated components. The next step involved in reliability assessment is to appropriately model the system components to represent their characteristics and functions in the overall system. The unified power flow controller (UPFC) is an important flexible AC transmission system controller that can be used to enhance power system reliability. A complete reliability model of a UPFC is developed. A UPFC consists of three subsystems, and a reliability model associated with each subsystem is developed. The individual equivalent models are...