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Optimal distribution transformer sizing in a harmonic involved load environment via dynamic programming technique
, Article Energy ; Volume 120 , 2017 , Pages 92-105 ; 03605442 (ISSN) ; Mohiti, M ; Farzin, N ; Vakilian, M ; Sharif University of Technology
2017
Abstract
Installation of a significant number of distributed generators (DGs), besides the application of non-sinusoidal loads such as; Plug-in Hybrid Electric Vehicles (PHEVs), in the emerging smart distribution networks and the industrial plants have posed a major challenge to the existing methods of optimal transformer sizing (OTS). The harmonic currents generated in these new environments not only substantially increase the transformer load losses, but also cause abnormal winding temperature rise and hence transformer excessive loss of life. Therefore, the harmonic contents of the loads currents should be accounted in choosing the appropriate size of distribution transformers. To address this...
New Hybrid Approaches Information Clustering Based on FCM Clustering and Optimization CFA
, M.Sc. Thesis Sharif University of Technology ; Ramezanian, Rasoul (Supervisor)
Abstract
Clustering algorithms are developed to provide general attitudes on database, recognizing latent structures and their more effective accessibility. Recently, broad studies are conducted on clustering since it is recognized as an important tool to explore and analyze data. Clustering is a fundamental learning operation without monitoring in data exploration which divides data into groups of objects so that objects in one group have the most similarity to each other and lowest similarity to objects in other groups. Some clustering algorithms such fuzzy clustering model (FCM) are widely used in clustering problem solution although this technique addresses local optimized searches. Additionally,...
Reliability Studies of a Smart Distribution System Based on the Concept of Multi-microgrid
, Ph.D. Dissertation Sharif University of Technology ; Fotuhi Firuzabad, Mahmud (Supervisor)
Abstract
Current trend of energy consumption and aging infrastructure of electricity grids mandates high amounts of investment in transmission and distribution networks. On the other hand, with increased awareness about environmental issues, share of renewable energy resources in power generation portfolio has risen in recent years. Microgrids, as one of the most promising solutions to tackle these issues, are able to accommodate high penetration levels of renewable energy sources and distributed generation in distribution systems. However, microgrids sizes are limited due to some operational considerations and as a result, efficient management of distribution systems with high penetration of...
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) ; Vakilian, M ; Farzin, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
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...
Transformer practical turn-to-turn fault detection performance using negative sequence and space vector-based methods
, Article 13th International Conference on Protection and Automation of Power System, IPAPS 2019, 8 January 2019 through 9 January 2019 ; 2019 , Pages 1-6 ; 9781728115054 (ISBN) ; Vakilian, M ; Hajipour, E ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Transformer turn-to-turn fault (TTF) is one of the most difficult failures to detect. The negative sequence percentage differential current (NSPD) and extended park vectors approach (EPVA) are the two most promising methods for detection of the TTF inception. In this paper, in order to evaluate the performance of these methods, various experimental tests are carried out to detect the TTF initiation on the winding of the transformer under different operating conditions such as: No-load operation, when an external fault or an open conductor fault is also occurred. The results show that the setting of the proper thresholds plays the main role in the reliable and secure performance of NSPD and...
Practical implementation of a new percentage-based turn-to-turn fault detection algorithm to transformer digital differential relay
, Article International Journal of Electrical Power and Energy Systems ; Volume 121 , 2020 ; Vakilian, M ; Hajipour, E ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Turn-to-turn fault (TTF) is one of the most prominent reasons for transformer failure. This fault typically initiates by involving only a few turns and can progress to a much more severe fault in a very short time. Therefore, it is critical for the transformer protective relays to detect the TTF in the early stages of its occurrence. The conventional differential relays, in general, cannot detect a minor TTF, and thus, a supplementary protective algorithm is usually required to improve the sensitivity of differential relays against TTFs. This paper proposes a percentage-based fault-related incremental currents method for the precise detection of a low-level TTF. The proposed method employs...
Transformer turn-to-turn fault protection based on fault-related incremental currents
, Article IEEE Transactions on Power Delivery ; Volume 34, Issue 2 , 2019 , Pages 700-709 ; 08858977 (ISSN) ; Vakilian, M ; Hajipour, E ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Winding turn-to-turn fault (TTF) is one of the most reported reasons for transformer unplanned outage. If its occurrence is not detected at an early stage, it can develop into a costly phase-to-ground fault. In this paper, a novel algorithm based on the fault-related incremental currents is proposed to detect a low-level transformer TTF. This paper shows that the performance of the proposed method is independent of the transformer operating condition. Therefore, it is reliable even under the presence of power system transients such as the external faults. In addition, the proposed algorithm can be configured uniquely and easily. This feature prevents the algorithm from unnecessary trips....
3D-Printed Sugar-Based Stents Facilitating Vascular Anastomosis
, Article Advanced Healthcare Materials ; 2018 ; 21922640 (ISSN) ; Miri, A. K ; Sharifi, F ; Faramarzi, N ; Jaberi, A ; Mostafavi, A ; Solorzano, R ; Zhang, Y. S ; Annabi, N ; Khademhosseini, A ; Tamayol, A ; Sharif University of Technology
Wiley-VCH Verlag
2018
Abstract
Microvascular anastomosis is a common part of many reconstructive and transplant surgical procedures. While venous anastomosis can be achieved using microvascular anastomotic coupling devices, surgical suturing is the main method for arterial anastomosis. Suture-based microanastomosis is time-consuming and challenging. Here, dissolvable sugar-based stents are fabricated as an assistive tool for facilitating surgical anastomosis. The nonbrittle sugar-based stent holds the vessels together during the procedure and are dissolved upon the restoration of the blood flow. The incorporation of sodium citrate minimizes the chance of thrombosis. The dissolution rate and the mechanical properties of...
An Improved aggregated model of residential air conditioners for FIDVR studies
, Article IEEE Transactions on Power Systems ; Volume 35, Issue 2 , 2020 , Pages 909-919 ; Saber, H ; Farzin, N ; Karimi, M. R ; Hashemi, S. M ; Agheli, A ; Ayoubzadeh, H ; Ehsan, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
Stalling of residential air conditioners (RACs) following a transient fault can delay the voltage recovery ranging from 3 to 20 seconds. This phenomenon is referred to as fault-induced delayed voltage recovery (FIDVR). Several aggregated RAC models have been presented to replicate the actual FIDVR events. However, they usually have two main drawbacks as: i) considering independent stalling voltage and stalling time for all RACs, ii) resulting in only two ultimate modes; either 100% stalled or 100% normal running. This paper amends the abovementioned shortcomings by proposing a simple and effective performance-based RAC model. The proposed model utilizes a simple explicit relation between the...
Investigating the effect of ambient temperature on fault-induced delayed voltage recovery events
, Article IET Generation, Transmission and Distribution ; Volume 14, Issue 9 , 2020 , Pages 1781-1790 ; Karimi, M. R ; Hajipour, E ; Farzin, N ; Hashemi, S. M ; Agheli, A ; Ayoubzadeh, H ; Ehsan, M ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
The high penetration of residential air conditioners (RACs) poses a growing concern in emerging fault-induceddelayed voltage recovery (FIDVR) in power systems. FIDVR is expected to be a significant threat to the stability and reliability offuture power grids. Hence, the system planners should carry out appropriate simulation studies to mitigate the severeconsequences of FIDVR events. A key question to implement these studies is how to determine the worst condition whichresults in FIDVR. Most of the actual FIDVR events have been experienced in the hot hours of the day and this issue makes onecurious to think about the relationship between the FIDVR events and the ambient temperature. In this...
Reliability evaluation of power grids considering integrity attacks against substation protective IEDs
, Article IEEE Transactions on Industrial Informatics ; Volume 16, Issue 2 , 2020 , Pages 1035-1044 ; Fotuhi Firuzabad, M ; Farzin, H ; Sharif University of Technology
IEEE Computer Society
2020
Abstract
Secure operation of protective intelligent electronic devices (IEDs) has been recognized as a crucial issue for power grids. By gaining access to substation IEDs, intruders can severely disrupt the operation of protection systems. This paper develops an analytical reliability assessment framework for quantifying the impacts of the hypothesized integrity attacks against protection systems. Petri net models are used to simulate possible intrusion scenarios into substation networks. The cyber network model is constructed from firewall, intrusion prevention system (IPS), and password models, which are three types of defense mechanisms for protecting substation networks. In this paper, two main...
A risk-based resilient distribution system planning model against extreme weather events
, Article IET Renewable Power Generation ; Volume 16, Issue 10 , 2022 , Pages 2125-2135 ; 17521416 (ISSN) ; Ehsan, M ; Farzin, H ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
Due to the accelerated climate change, it is anticipated that the number and severity of natural disasters such as hurricanes, blizzards, and floods will be increased in the coming years. In this regard, this paper presents a distribution system planning model to improve the system resilience against hurricane. A scenario-based mathematical model is proposed to capture the random nature of weather events. Moreover, a stochastic optimization model is developed to simultaneously harden the distribution lines and place different types of distributed generation (DG) units such as microturbines (MTs), wind turbines (WTs), and photovoltaic cells (PVs). The conditional value at risk (CVaR) is used...
An Milp model for switch, DG, and tie line placement to improve distribution grid reliability
, Article IEEE Systems Journal ; 2022 , Pages 1-12 ; 19328184 (ISSN) ; Ehsan, M ; Farzin, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Remote controlled switches (RCSs) have the ability to isolate the faulted area from other parts of the distribution system. On the other hand, the dispatchable distributed generators (DDGs) and tie lines can supply the interrupted loads after fault occurrence trough microgrids and reduce the outage time. In this regard, this article proposes a planning model for simultaneous placement of RCSs, DDGs, and tie lines to improve distribution system reliability. The presence of renewable distributed generations (RDGs) and energy storage systems, which have an increasing penetration in today's distribution networks are also considered. Moreover, two different practical load shedding methods are...
A hierarchical scheme for outage management in multi-microgrids
, Article International Transactions on Electrical Energy Systems ; Volume 26, Issue 9 , 2016 , Pages 2023-2037 ; 20507038 (ISSN) ; Moeini Aghtaie, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
John Wiley and Sons Ltd
2016
Abstract
This paper investigates the operation of a smart distribution system comprised of multiple microgrids during emergency conditions. It proposes a two-stage hierarchical scheme for outage management in such a system to enhance the security of supply during contingencies. This goal is achieved through sharing the available generation and storage capacities among different microgrids. In doing so, a well-organized framework is devised in order to introduce the roles and tasks of each player in operation stage of a multi-microgrids system. Based on this framework, the general optimization model that needs to be evaluated at each stage of the proposed outage management scheme is formulated. In...
Enhancing power system resilience through hierarchical outage management in multi-microgrids
, Article IEEE Transactions on Smart Grid ; Volume 7, Issue 6 , 2016 , Pages 2869-2879 ; 19493053 (ISSN) ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
This paper proposes a hierarchical outage management scheme to enhance the resilience of a smart distribution system comprised of multi-microgrids against unexpected disaster events. In this regard, after identifying the main features and requirements for a resilient outage management scheme, an appropriate framework is devised and the roles and tasks of different management entities in a multi-microgrids system are introduced. Based on this framework, the microgrids schedule their available resources in the first stage using a novel model predictive control-based algorithm. In the second stage, distribution system operator coordinates the possible power transfers among the microgrids and...
A practical scheme to involve degradation cost of lithium-ion batteries in Vehicle-to-Grid applications
, Article IEEE Transactions on Sustainable Energy ; Volume 7, Issue 4 , Volume 7, Issue 4 , 2016 , Pages 1730-1738 ; 19493029 (ISSN) ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
This paper concentrates on degradation of electric vehicle (EV) lithium-ion batteries in vehicle-to-grid (V2G) programs and proposes a practical wear cost model for EVs charge scheduling applications. As the first step, all the factors affecting the cycle life of lithium-ion batteries are identified and their impacts on degradation process are investigated. Subsequently, a general model for battery loss of cycle life is devised incorporating all the pertinent factors associated with charging and discharging activities in V2G applications. Modeling the battery wear cost as a series of equal-payments over the cycle life, a mechanism for calculating the cost incurred by EV users due to...
Developing a hierarchical scheme for outage management in multi-microgrids
, Article IEEE Eindhoven PowerTech, PowerTech 2015 ; 2015 ; 9781479976935 (ISBN) ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
2015
Abstract
This paper investigates the performance of a smart distribution system comprised of multi-microgrids during emergency conditions. It also proposes a hierarchical scheme for outage management in such a system to enhance the security of supply during contingencies. This goal is achieved through sharing the available generation and storage capacities among different microgrids. In this regard, at first, a well-organized framework is devised in order to introduce the roles and tasks of each player in operation stage of a multi-microgrids system. Based on this framework, the general optimization model that needs to be evaluated in the proposed outage management scheme is formulated. Then, various...
Reliability Studies of Modern Distribution Systems Integrated With Renewable Generation and Parking Lots
, Article IEEE Transactions on Sustainable Energy ; Volume PP, Issue 99 , 2016 ; 19493029 (ISSN) ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
This paper investigates the role of parking lots in improving the reliability of renewable-based distribution systems, through provision of vehicle-to-grid (V2G) programs during outage events. In this regard, municipal parking decks are viewed as distributed energy storage systems and the amount of available energy from these units in random contingency events is probabilistically modeled for reliability studies. Appropriate stochastic models are also introduced to capture the volatility and intermittency of renewable sources. Moreover, it is discussed that how the adopted outage management scheme (OMS) in contingency events can affect the reliability level of customers. In response, several...
A stochastic multi-objective framework for optimal scheduling of energy storage systems in microgrids
, Article IEEE Transactions on Smart Grid ; Volume PP, Issue 99 , 2016 ; 19493053 (ISSN) ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
This paper presents a stochastic framework for day-ahead scheduling of microgrid energy storage systems (ESSs) in the context of multi-objective (MO) optimization. Operation cost of microgrid in normal conditions and load curtailment index in case of unscheduled islanding events (initiated by disturbances in the main grid) are chosen as main criteria of the proposed scheme. In practice, duration of disconnection from the upstream network is unknown in unscheduled islanding incidents and cannot be predicted with certainty. To properly handle the uncertainties associated with time and duration of such events as well as microgrid load and renewable power generation, stochastic models are...
A dynamic programing-based framework for distribution system restoration considering load uncertainties
, Article International Transactions on Electrical Energy Systems ; Volume 27, Issue 12 , 2017 ; 20507038 (ISSN) ; Abbaspour, A ; Farzin, H ; Khalili, S ; Sharif University of Technology
2017
Abstract
This paper presents a stochastic framework to properly involve the uncertainties associated with demand in distribution system restoration (DSR) problem. To reach this goal, these uncertainties are represented as probabilistic scenarios corresponding to different load levels. Subsequently, the associated stochastic optimization problem is formulated such that it can be readily solved using dynamic programming approach. Moreover, a clustering technique is presented that enables the dynamic programming approach to find near-optimal solutions for the stochastic load restoration problem with reasonable computational effort. The proposed framework is implemented on a real-world test system, and...