Search for: critical-loads
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    Distribution System Resilience Enhancement through Restoration Paths between DERs and Critical Loads

    , Article 24th Electrical Power Distribution Conference, EPDC 2019, 19 June 2019 through 20 June 2019 ; 2019 , Pages 1-5 ; 9781728133850 (ISBN) Bahrami, M ; Vakilian, M ; Farzin, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Hardening and operational measures in electrical distribution systems (EDSs) aim at improving the resilience of EDS in case of natural disasters. This paper proposes a novel two-stage framework for establishing optimal restoration paths for supplying critical loads (CLs) in the aftermath of a natural disaster that will improve the resilience of EDSs. To this end, in the first stage, an algorithm is introduced to find all possible candidate paths between available distributed energy resources (DERs) and CLs, the output of which is applied to the second stage, as the inputs. Subsequently, in the second stage, the problem of finding the optimal restoration paths is modeled as a mixed integer... 

    Stability analysis of nanocones under external pressure and axial compression using a nonlocal shell model

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 44, Issue 9 , June , 2012 , Pages 1832-1837 ; 13869477 (ISSN) Firouz Abadi, R. D ; Fotouhi, M. M ; Haddadpour, H ; Sharif University of Technology
    A nonlocal continuum shell model is developed to study the stability of nanocones under combined loading: external pressure and compression force. The nonlinear governing equations of motion of nanocone are obtained using Hamiltons principle and the external loads are considered as prestress. Based on Eringens nonlocal elasticity theory the small-scale effect is accounted in the governing equations of motion. To obtain the critical loads, the equations are solved using Galerkin technique and the effect of small-scale parameter and geometry on the stability of nanocone is studied  

    On secondary control approaches for voltage regulation in DC microgrids

    , Article IEEE Transactions on Industry Applications ; Volume 53, Issue 5 , 2017 , Pages 4855-4862 ; 00939994 (ISSN) Peyghami, S ; Mokhtari, H ; Davari, P ; Loh, P. C ; Blaabjerg, F ; Sharif University of Technology
    Centralized or decentralized secondary controller is commonly employed to regulate the voltage drop raised by the primary controller. However, in the case of high capacity microgrids (MGs) and long feeders with much voltage drop on the line resistances, the conventional methods may not guarantee the voltage regulation on the load busses within a suitable range. Therefore, in addition to compensate the voltage drop of the primary controller, it is necessary to regulate the voltage of critical loads. In this paper, a new voltage regulation strategy is proposed to regulate the voltage of MG by employing the average voltage of identified critical busses, which are determined by the proposed... 

    Effect of porosity on buckling and vibrational characteristics of the imperfect GPLRC composite nanoshell

    , Article Mechanics Based Design of Structures and Machines ; Volume 49, Issue 6 , 2021 , Pages 811-840 ; 15397734 (ISSN) Habibi, M ; Mohammadi, A ; Safarpour, H ; Ghadiri, M ; Sharif University of Technology
    Bellwether Publishing, Ltd  2021
    Due to rapid development of manufacturing process, composite materials with porosity have attracted commercially notices in advanced engineering applications. For this regard, buckling and vibrational characteristics of a porous composite cylindrical nanoshell reinforced with GPLs is investigated in this paper. The material properties of piece-wise graphene-reinforced composites (GPLRC) are assumed to be graded in the thickness direction of a cylindrical nanoshell and are estimated using a nanomechanical model. The novelty of our work is including the effects of porosity and GPLRC on natural frequency, critical axial load and critical temperature of the GPLRC cylindrical nanoshell. The... 

    Search for critical loading condition of the spine-A meta analysis of a nonlinear viscoelastic finite element model

    , Article Computer Methods in Biomechanics and Biomedical Engineering ; Volume 8, Issue 5 , 2005 , Pages 323-330 ; 10255842 (ISSN) Wang, J. L ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology
    The relative vulnerability of spinal motion segments to different loading combinations remains unknown. The meta-analysis described here using the results of a validated L2-L3 nonlinear viscoelastic finite element model was designed to investigate the critical loading and its effect on the internal mechanics of the human lumbar spine. A Box-Behnken experimental design was used to design the magnitude of seven independent variables associated with loads, rotations and velocity of motion. Subsequently, an optimization method was used to find the primary and secondary variables that influence spine mechanical output related to facet forces, disc pressure, ligament forces, annulus matrix... 

    Application of homotopy-Pade technique in limit analysis of circular plates under arbitrary rotational symmetric loading using von-Mises yield criterion

    , Article Communications in Nonlinear Science and Numerical Simulation ; Volume 15, Issue 4 , 2010 , Pages 1080-1091 ; 10075704 (ISSN) Kargarnovin, M. H ; Faghidian, S. A ; Farjami, Y ; Farrahi, G. H ; Sharif University of Technology
    The upper and lower bound principals of limit analysis are employed to determine the critical loading on solid circular plate with simply supported boundary conditions and subjected to any distributed loading with rotational symmetry. In this study, material behavior follows a rigid perfectly plastic model and yielding obeys the von-Mises criterion. Homotopy analysis method is employed to achieve the analytical solution to the high nonlinear ordinary differential equations governing the problem. This analytic solution has been obtained in terms of convergent series with easily computable terms. The results are verified with the Tresca yield criterion and presented as plots to show the... 

    A novel method to assess distribution system reliability considering smart solar cell

    , Article 2012 2nd Iranian Conference on Smart Grids, ICSG 2012, 23 May 2012 through 24 May 2012 ; May , 2012 , Page(s): 1 - 9 ; 9781467313995 (ISBN) Rastegar, M ; Fotuhi Firuzabad, M ; Safdarian, A ; Sharif University of Technology
    One of the most important issues in the smart grid is to quantitatively assess the impacts of distributed energy resources (DER) on the distribution system reliability. Solar cells (SCs) as developing DERs are normally placed close to the load centers. In this paper, a new algorithm is developed to evaluate distribution system reliability, considering SCs in the vicinity of the end-users. The probabilistic nature of the demand and SC power output are investigated to solve challenges of integrating these intermittent resources with the distribution system. In a smart home, to handle the variation of SC generation, solar load controller (SLC) is utilized to match load and generation of SCs... 

    A game theory approach for maximum utilization of wind power by DR in residential consumers

    , Article 10th IEEE PES Innovative Smart Grid Technologies Europe, ISGT-Europe 2020, 26 October 2020 through 28 October 2020 ; Volume 2020-October , 2020 , Pages 111-115 Tavakkoli, M ; Fattaheian Dehkordi, S ; Pourakbari Kasmaei, M ; Liski, M ; Lehtonen, M ; IEEE Power and Energy Society ; Sharif University of Technology
    IEEE Computer Society  2020
    This paper proposes an indirect load control demand response (DR) strategy for residential houses. A Stackelberg game theory is applied to account for the interaction between the aggregator in one side and the consumers on the other side. The aggregator, which owns a wind power plant, strives to maximize wind power utilization by consumers. Therefore, it motivates the consumers to adjust their load demand according to the forecasted wind power production by offering a bonus to them. On the other hand, consumers attempt to achieve the highest amount of reward by changing their load profile. It is assumed that each consumer has a critical load of which they have no control, and also a flexible...