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    Modeling of D-STATCOM in distribution systems load flow

    , Article Journal of Zhejiang University: Science A ; Volume 8, Issue 10 , 2007 , Pages 1532-1542 ; 1673565X (ISSN) Hosseini, M ; Shayanfar, H. A ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2007
    Abstract
    This paper presents modeling of Distribution STATCOM (D-STATCOM) in load flow calculations for the steady-state voltage compensation. An accurate model for D-STATCOM is derived to use in load flow calculations. The rating of this device as well as the direction of required reactive power injection for voltage compensation in the desired value (1 p.u.) is derived and discussed analytically and mathematically by the phasor diagram method. Furthermore, an efficient method for node and line identification used in load flow calculations is presented. The validity of the proposed model is examined by using two standard distribution systems consisting of 33 and 69 nodes, respectively. The best... 

    Modeling of Static Series Voltage Regulator (SSVR) in distribution systems for voltage improvement and loss reduction

    , Article Leonardo Electronic Journal of Practices and Technologies ; Volume 7, Issue 12 , 2008 , Pages 61-82 ; 15831078 (ISSN) Hosseini, M ; Shayanfar, H. A ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2008
    Abstract
    This paper introduces the modeling of Static Series Voltage Regulator (SSVR) in the load flow calculations for steady-state voltage compensation and loss reduction. For this approach, an accurate model for SSVR is derived to use in load flow calculations. The rating of this device as well as direction of required reactive power injection to compensate voltage to the desired value (1p.u.) is derived, discussed analytically, and mathematically using phasor diagram method. Since performance of SSVR varies when it reaches to its maximum capacity, modeling of SSVR in its maximum rating of reactive power injection is derived. The validity of the proposed model is examined using two standard... 

    Transmission Expansion Planning Considering Uncertainty in Generation and N-1 Criterion

    , M.Sc. Thesis Sharif University of Technology Karimi Gharigh, Mohammad Reza (Author) ; Ehsan , Mehdi (Supervisor)
    Abstract
    In order to reduce investment and operation costs of the power systems, transmission expansion planning is inevitable. In fact, transmission expansion planning is to determine when, where and how many lines need to be added to power system with a minimum of investment and operating costs. In this thesis, transmission expansion planning has been performed at uncertainty in generation and N-1 criterion condition where uncertainty in generation means uncertainty in the moment of adding power plant to power system. In previous studies, transmission expansion planning was performed with DC-load flow in which, the power loss and voltage profiles were ignored due to the approximation in the... 

    The evaluation of the confidence intervals for the state parameters of a DC power system

    , Article Journal of Engineering and Applied Sciences ; Volume 12, Issue 18 , 2017 , Pages 4544-4550 ; 1816949X (ISSN) Khan, Z ; Razalia, R ; Daud, H ; Norc, N. M ; Firuzabad, M. F ; Sharif University of Technology
    Abstract
    State estimation in power engineering is used as a tool to find the unknown parameter values from the hypothesized model by utilizing the specified information available about the system. Due to random noises that are added from different sources, the exact value of the state vector cannot be found. This study is an effort to describe the simultaneous and individual confidence intervals for the state parameters in view of the heteroscedastic structure of the error terms. The performance of the constructed intervals in terms of coverage probability has been evaluated by using the Monte Carlo simulation study. The results of the study demonstrate that it is an effective method for practical... 

    Probabilistic load flow in correlated uncertain environment using unscented transformation

    , Article IEEE Transactions on Power Systems ; Volume 27, Issue 4 , 2012 , Pages 2233-2241 ; 08858950 (ISSN) Aien, M ; Fotuhi Firuzabad, M ; Aminifar, F ; Sharif University of Technology
    2012
    Abstract
    As a matter of course, the unprecedented ascending penetration of distributed energy resources, mainly harvesting renewable energies, is a direct consequence of environmental concerns. This type of energy resource brings about more uncertainties in power system operation and planning; consequently, it necessitates probabilistic analyses of the system performance. This paper develops a new approach for probabilistic load flow (PLF) evaluation using the unscented transformation (UT) method. The UT method is recognized as a powerful approach in assessing stochastic problems with/without correlated uncertain variables. The capability of the UT method in modeling correlated uncertain variables is... 

    Value-based reserve market settlement

    , Article IET Generation, Transmission and Distribution ; Volume 10, Issue 9 , 2016 , Pages 2216-2224 ; 17518687 (ISSN) Nouri, A ; Hosseini, S. H ; Sharif University of Technology
    Institution of Engineering and Technology  2016
    Abstract
    The main focus of this study is on reserve market settlement in an electricity market with marginal pricing scheme as the pricing mechanism. Following a day-ahead market clearing, the marginal prices are found using the appropriate Lagrange multipliers as the bi-products of the optimisation process. The payments to energy and reserve providers can then be found based on these prices. However, it is hard to find an appropriate settlement scheme that provides the fair and justifiable consumer payments based on marginal pricing scheme considering the actual reserve functions in power systems. In this study, a reserve marginal pricing that is based on a proper reserve marginal price definition... 

    Autonomous operation of a hybrid AC/DC microgrid with multiple interlinking converters

    , Article IEEE Transactions on Smart Grid ; Volume 9, Issue 6 , 2018 , Pages 6480-6488 ; 19493053 (ISSN) Peyghami, S ; Mokhtari, H ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Applying conventional dc-voltage-based droop approaches for hybrid ac/dc microgrids interconnected by a single interlinking converter (IC) can properly manage the power flow among ac and dc subgrids. However, due to the effect of line resistances, these approaches may create a circulating power as well as overstressing the ICs in the case of employing multiple ICs for interconnecting the ac and dc subgrids. This paper proposes an autonomous power sharing approach for hybrid microgrids interconnected through multiple ICs by introducing a superimposed frequency in the dc subgrid. Hence, a suitable droop approach is presented to manage the power among the dc and ac sources as well as ICs. The... 

    A linear AC power flow model for unbalanced multi-phase distribution networks based on current injection equations

    , Article IEEE Transactions on Power Systems ; Volume 36, Issue 4 , 2021 , Pages 3806-3809 ; 08858950 (ISSN) Heidari-Akhijahani, A ; Safdarian, A ; Vrakopoulou, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Abstract
    A realistic and practicable modeling of unbalanced distribution networks (DNs) is the missing link in most studies undertaken in these networks, e.g., optimal power flow (OPF), energy markets, etc. To address the issue, this letter proposes an unbalanced linear three-phase four-wire power flow (PF) model based on current injection equations at nodes. Also, the ZIP representation is considered for loads. The model can be easily generalized for unbalanced three-wire networks with minor changes and assumptions. Hence, the scope of the proposed method can be extended to cover both low-voltage and medium-voltage DNs. The performance of the proposed model is verified through simulations on two... 

    New approach to standing phase angle reduction for power system restoration

    , Article European Transactions on Electrical Power ; Volume 12, Issue 4 , 2002 , Pages 301-307 ; 1430144X (ISSN) Ketabi, A ; Ranjbar, A. M ; Feuillet, R ; Sharif University of Technology
    2002
    Abstract
    During power system restoration, it is necessary to check the phase angle between two buses before closing circuit breakers to connect a line between them. These angles may occur across a tie line between two systems or between two connected subsystems within a system. In case of large Standing Phase Angle (SPA) difference the synchrocheck relay does not allow closing of the breaker for this line. Therefore, this excessive SPA has to be reduced before attempting to connect the line. In this paper a new and fast method for reducing SPA is presented. For this purpose, the standing phase angle difference between two specific buses is represented in terms of sensitivity factors associated with... 

    Probabilistic load flow in correlated uncertain environment using unscented transformation

    , Article IEEE Transactions on Power Systems ; Vol. 27, issue. 4 , 2012 , p. 2233-2241 ; ISSN: 08858950 Aien, M ; Fotuhi-Firuzabad, M ; Aminifar, F ; Sharif University of Technology
    Abstract
    As a matter of course, the unprecedented ascending penetration of distributed energy resources, mainly harvesting renewable energies, is a direct consequence of environmental concerns. This type of energy resource brings about more uncertainties in power system operation and planning; consequently, it necessitates probabilistic analyses of the system performance. This paper develops a new approach for probabilistic load flow (PLF) evaluation using the unscented transformation (UT) method. The UT method is recognized as a powerful approach in assessing stochastic problems with/without correlated uncertain variables. The capability of the UT method in modeling correlated uncertain variables is... 

    Optimal distributed static series compensator placement for enhancing power system loadability and reliability

    , Article IET Generation, Transmission and Distribution ; Volume 9, Issue 11 , 2015 , Pages 1043-1050 ; 17518687 (ISSN) Dorostkar Ghamsari, M ; Fotuhi Firuzabad, M ; Aminifar, F ; Safdarian, A ; Lehtonen, M ; Sharif University of Technology
    Institution of Engineering and Technology  2015
    Abstract
    Distributed static series compensator (DSSC) is a member of the family of distributed flexible AC transmission system devices that can be attached directly to conductors of transmission lines. DSSCs are able to compensate for and adjust the line reactance; thus, they could be widely used in stability-limited transmission systems. Owing to economic matters, the optimal placement of DSSCs is of a great interest from practical viewpoints. This study presents an approach to find the optimal locations of DSSCs to enhance the system loadability and reliability using the DC load flow model. The optimisation problem is solved using the mixed-integer linear programming. A compromise between improving... 

    Modeling of unified power quality conditioner (UPQC) in distribution systems load flow

    , Article Energy Conversion and Management ; Volume 50, Issue 6 , 2009 , Pages 1578-1585 ; 01968904 (ISSN) Hosseini, M ; Shayanfar, H. A ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2009
    Abstract
    This paper presents modeling of unified power quality conditioner (UPQC) in load flow calculations for steady-state voltage compensation. An accurate model for this device is derived to use in load flow calculations. The rating of this device as well as direction of reactive power injection required to compensate voltage to the desired value (1 p.u.) is derived and discussed analytically and mathematically using phasor diagram method. Since performance of the compensator varies when it reaches to its maximum capacity, modeling of UPQC in its maximum rating of reactive power injection is derived. The validity of the proposed model is examined using two standard distribution systems consisting... 

    Modeling of Series Static Voltage Restorer (SSVR) in distribution systems load flow

    , Article 2007 Large Engineering Systems Conference on Power Engineering, LESCOPE'07, Montreal, QC, 10 October 2007 through 12 October 2007 ; January , 2007 , Pages 310-315 ; 9781424415830 (ISBN) Fotuhi Firuzabad, M ; Shayanfar, H. A ; Hosseini, M ; Sharif University of Technology
    2007
    Abstract
    This paper presents modeling of Series Static Voltage Restorer (SSVR) in load flow calculations for steadystate voltage compensation. An accurate model for SSVR is derived to use in load flow calculations. The rating of this device as well as direction of required reactive power injection to compensate voltage to the desired value (1p.u.) is derived and discussed analytically and mathematically using pahsor diagram method. Since performance of SSVR varies when it reaches to its maximum capacity, modeling of SSVR in its maximum rating of reactive power injection is derived. The validity of the proposed model is examined using two standard distribution systems consisting of 33 and 69 nodes,... 

    Probabilistic analysis to analyze uncertainty incorporating copula theory

    , Article Journal of Electrical Engineering and Technology ; Volume 17, Issue 1 , 2022 , Pages 61-71 ; 19750102 (ISSN) Li, B ; Shahzad, M ; Munir, H. M ; Nawaz, A ; Fahal, N. A. M ; Khan, M. Y. A ; Ahmed, S ; Sharif University of Technology
    Korean Institute of Electrical Engineers  2022
    Abstract
    The emerging trend of distribution generation with existing power system network leads uncertainty factor. To handle this uncertainty, it is a provocation for the power system control, planning, and operation engineers. Although there are numerous techniques to model and evaluate these uncertainties, but in this paper the integration of Copula theory with Improved Latin-hypercube Sampling (ILHS) are incorporated for Probabilistic load Flow (PLF) evaluation. In probabilistic research approaches, the dominant interest is to achieve appropriate modelling of input random variables and reduce the computational burden. To address the said problem, Copula theory is applied to execute the modelling... 

    Model Predictive Controller Design for Regenerative Electronic AC Load

    , M.Sc. Thesis Sharif University of Technology Akhlaghi, Sadegh (Author) ; Zolghadri, MohammadReza (Supervisor)
    Abstract
    Generally, virtual loads is used to test all AC power and energy meters and are usually passive. To prevent possible damage of this heat and to control the temperature, cooling blowers are used which increases the volume and weight. So, recycling the power delivered from the grid causes a small amount of power to be converted to heat in proportion to the load efficiency. The purpose of this study is design, predictive controller model for programmable electronic regenerative AC load. The structure used is a back-to-back converter consisting of an AC-DC converter and a DC-AC converter, which according to existence of capacitance between these two structures, two converters can be controlled... 

    A decomposed solution to multiple-energy carriers optimal power flow

    , Article IEEE Transactions on Power Systems ; Vol. 29, issue. 2 , March , 2014 , p. 707-716 ; ISSN: 8858950 Moeini-Aghtaie, M ; Abbaspour, A ; Fotuhi-Firuzabad, M ; Hajipour, E ; Sharif University of Technology
    Abstract
    Presence of energy hubs in the future vision of energy networks creates a great opportunity for system planners and operators to move towards more efficient systems. The role of energy hubs as the intermediate in multi-carrier energy (MCE) systems calls for a generic framework to study the new upcoming technical as well as economical effects on the system performance. In response, this paper attempts to develop a general optimization and modeling framework for coupled power flow studies on different energy infrastructures. This, as a large-scale nonlinear problem, is approached through a robust optimization technique, i.e., multi-agent genetic algorithm (MAGA). The proposed procedure... 

    Security constrained unit commitment with flexibility in natural gas transmission delivery

    , Article Journal of Natural Gas Science and Engineering ; Volume 27, Part 2 , November 2015 , 2015 , Pages 632–640 ; 18755100 (ISSN) Badakhshan, S ; Kazemi, M ; Ehsan, M ; Sharif University of Technology
    Elsevier  2015
    Abstract
    This paper presents a formulation of fuzzy optimization for uncertainties in natural gas in fuel constraints for hourly individual unit and total unit fuel consumptions. Security Constrained Unit Commitment (SCUC) is usually a mixed integer programming and gas load flow has a non-linear equation a genetic algorithm is proposed to solve natural gas transmission network. A fuzzy mixed integer programming optimization is briefly discussed and adapted to deal with security constrained unit commitment schedule. Finally, two case studies are investigated (IEEE 6-bus system with 7-node natural gas transmission grid and the IEEE 118-bus power system linked with 14-node gas transmission test system)... 

    Smart power management of DC microgrids in future milligrids

    , Article 2016 18th European Conference on Power Electronics and Applications, EPE 2016 ECCE Europe, 5 September 2016 through 9 September 2016 ; 2016 ; 9789075815245 (ISBN) Peyghami Akhuleh, S ; Mokhtari, H ; Davari, P ; Loh, P. C ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    In this paper a novel droop approach for power management in low voltage dc MicroGrids (MGs) based on a master-slave concept is presented. A virtual frequency is injected by a master unit, which is proportional to its output power. Other slave units determine their output power according to the corresponding frequency based droop characteristics. Unlike the dc voltage-droop methods, the proposed virtual frequency-droop approach can be smartly applied for proportional power management among the energy units and loads as well as adding zero net energy capability to the MG. Both power flow and energy flow can be performed without utilizing an extra communication system. Simulation results... 

    Application of bat optimization algorithm in optimal power flow

    , Article 24th Iranian Conference on Electrical Engineering, ICEE 2016, 10 May 2016 through 12 May 2016 ; 2016 , Pages 793-798 ; 9781467387897 (ISBN) Delkhosh Abatari, H ; Seyf Abad, M. S ; Seifi, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    In this paper, Bat Algorithm is proposed to solve the Optimal Power Flow (OPF) problem. The approach employs a Meta heuristic optimization algorithm called bat optimization algorithm to determine the optimal settings of control variables of OPF problem. The performance of proposed method examined on the IEEE 9, 14, 30 and 57-buses test systems with fuel cost minimization as the objective function. The numerical results are compared to those of Particle Swarm Optimization (PSO), Harmony Search (HS) and Cuckoo algorithms. Simulation results obtained from the proposed approach demonstrate that this method provide effective and robust high-quality answer for the OPF problem. © 2016 IEEE  

    Multi-body simulation of a flapping-wing robot using an efficient dynamical model

    , Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 38, Issue 1 , 2016 , Pages 133-149 ; 16785878 (ISSN) Jahanbin, Z ; Selk Ghafari, A ; Ebrahimi, A ; Meghdari, A ; Sharif University of Technology
    Springer Verlag 
    Abstract
    The aim of this article is to present an efficient dynamical model for simulating flapping robot performance employing the bond graph approach. For this purpose, the complete constitutive elements of the system under investigation, including the main body and accessories, flapping mechanism, flexible wings and propulsion system consisting of a battery, DC motors and gear boxes, are considered. A complete model of the system was developed appending bond graph models of the subsystems together utilizing appropriate junctions. The wings were also modeled using ANSYS only for an initial evaluation. Moreover, a computer model was developed employing the block-oriented structure of Simulink in...