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A novel privacy-preserved voluntary outage management model on a transactive energy scheme
, Article IET Generation, Transmission and Distribution ; Volume 16, Issue 17 , 2022 , Pages 3462-3472 ; 17518687 (ISSN) ; Koochaki, M ; Moeini Aghtaie, M ; Abbaspour, A ; Mazaheri, H ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
Unpredictable occurrence of natural disasters in modern power systems has significantly increased the attentions to the outage management of multi-microgrid (MMG) systems. In this regard, a multi-objective two-stage outage management scheme is presented in this paper to protect undamaged microgrids (MGs) against load curtailment and minimize the curtailed loads simultaneously. Considering the importance of power system economic, this scheme is designed in a privacy-preserved transactive energy (TE) market and enables all MGs to participate in outage management voluntarily. In detail, a DC optimization is autonomously operated in the first stage in each MG to supply its demand loads. Then,...
Load sharing by decentralized control in an islanded voltage source converter-based Microgrid considering fixed frequency
, Article Indian Journal of Science and Technology ; Volume 9, Issue 6 , 2016 ; 09746846 (ISSN) ; Tavakoli, R ; Hassani, R ; Sharif University of Technology
Indian Society for Education and Environment
Abstract
Background/Objectives: In this paper by utilizing frequency tracking electrical loads are shared on voltage source converters and then by applying a proposed-supplementary control system, frequency changes during changing electrical loads inside network is omitted. Methods/Statistical Analysis: Using decentralized control in Microgrids and sharing loads on power generation units respect to their nominal capacity are unavoidable approaches to have stable and operational network. Droop control in load sharing is known as practical and significant solution. In droop control, units output frequency, changes proportional to output active power that is not preferable. Simulation results in PSCAD...
Operation of multi-carrier microgrid (MCMG) considering demand response
, Article Journal of Operation and Automation in Power Engineering ; Volume 7, Issue 1 , 2019 , Pages 119-128 ; 23224576 (ISSN) ; Jadid, S ; Ehsan, M ; Sharif University of Technology
University of Mohaghegh Ardabili, Faculty of Electrical Engineering
2019
Abstract
In this paper, the operation of a future distribution network is discussed under the assumption of a multi-carrier microgrid (MCMG) concept. The new model considers a modern energy management technique in electricity and natural gas networks based on a novel demand side management (DSM) which the energy tariff for responsive loads are correlated to the energy input of the network and changes instantly. The economic operation of MCMG is formulated as an optimization problem. In conventional studies, energy consumption is optimized from the perspective of each infrastructure user without considering the interactions. Here, the interaction of energy system infrastructures is considered in the...
Fault detection and protection strategy for islanded inverter-based microgrids
, Article IEEE Journal of Emerging and Selected Topics in Power Electronics ; 2019 ; 21686777 (ISSN) ; Mokhtari, H ; Blaabjerg, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper proposes a fault detection and protection strategy for islanded inverter-based microgrids (IBMGs). Reliable and accurate protection is one of the main challenges in the proliferation of modern microgrids (MGs). Considering the limited fault current of the voltage-frequency controlled inverter-based distributed energy resources (VF-IBDERs), the protection is more challenging in islanded IBMGs. In this regard, the control scheme of VF-IBDER with a current limiting strategy plays an important role. Due to the limited fault currents close to the converter nominal current, the conventional fault detection methods do not work properly. In addition, bi-directional fault currents worsen...
Fault detection and protection strategy for islanded inverter-based microgrids
, Article IEEE Journal of Emerging and Selected Topics in Power Electronics ; 2019 ; 21686777 (ISSN) ; Mokhtari, H ; Blaabjerg, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper proposes a fault detection and protection strategy for islanded inverter-based microgrids (IBMGs). Reliable and accurate protection is one of the main challenges in the proliferation of modern microgrids (MGs). Considering the limited fault current of the voltage-frequency controlled inverter-based distributed energy resources (VF-IBDERs), the protection is more challenging in islanded IBMGs. In this regard, the control scheme of VF-IBDER with a current limiting strategy plays an important role. Due to the limited fault currents close to the converter nominal current, the conventional fault detection methods do not work properly. In addition, bi-directional fault currents worsen...
Autonomous power management in LVDC microgrids based on a superimposed frequency droop
, Article IEEE Transactions on Power Electronics ; 2017 ; 08858993 (ISSN) ; Mokhtari, H ; Blaabjerg, F ; Sharif University of Technology
Abstract
In this paper a novel droop approach for autonomous power management in low voltage dc microgrids based on a master-slave concept is presented. Conventional voltage-based droop approaches suffer from poor power sharing due to line resistance effects on a virtual resistance, which is solved a by introducing a communication system to increase the current sharing accuracy. In this paper, a virtual frequency is superimposed by the master units, and slave units determine their output power according to the corresponding frequency-based droop characteristics. Unlike the voltage-droop methods, the proposed virtual frequency-droop approach can be applied for proportional power management among the...
Micro-Grid Protection in Presence of Inverter Based Distributed Generation
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
In this study, control and protection of low voltage microgrids have been analyzed. Studied microgrid takes the advantages of inverter based distributed generation. One of the most important issues in inverter based microgrids is the control of its distributed generation. Since, the low voltage networks have single phase loads and many imbalances, these imbalances can affect the control of IBDGs (inverter based distributed generations). This issue in the islanded mode of operation is the most important, because in this mode of operation, IBDGs control the network voltage and frequency.
In this thesis, the different control strategies of IBDGs are reviewed, and then modified to address...
In this thesis, the different control strategies of IBDGs are reviewed, and then modified to address...
Decentrilized Power Management in AC-DC Hybrid Microgirds
, Ph.D. Dissertation Sharif University of Technology ; Mokhtari, Hossein (Supervisor) ; Blaabjerg, Frede (Co-Advisor)
Abstract
Proliferation of Distributed Generations (DGs) introduces higher reliability, stability, and quality as well as lower power losses and operational costs to the power systems. Integrating smart-grid and microgrid technologies to the power systems will further improve the overall performance of the system. Moreover, DC microgrids create an infrastructure to supply DC loads by DC sources such as photovoltaic arrays, fuel cell modules, as well as storages, which in case, increases the energy conversion efficiency. Operating DC microgrids together with AC microgrids, therefore, will form a new distrib-ution system called hybrid AC/DC systems, in which the DC side is dynamically decoupled from the...
Improvement of Inverter-based AC Microgrids Protection Against Short Circuit
, Ph.D. Dissertation Sharif University of Technology ; Mokhtari, Hossein (Supervisor) ; Blaabjerg, Frede (Co-Supervisor)
Abstract
Inverter-based distributed generations (IBDGs) have gained special interest in the electricity supply chain due to the advancements in power electronics technology. Power electronic inverters provide high-efficiency energy conversion with full controllability over a wide operating range, and ancillary services such as reactive power support and active filtering. Considering the voltage and frequency control capability of power inverters, supplying inverter-based micro-grid (IBMG) loads is now pissible. Despite the significant opportunities associated with such sources, they introduce new challenges that should be addressed properly. Reliable and accurate protection against short circuit...
Automatic superimposed droop frequency control scheme for dc microgrids
, Article 2019 International Aegean Conference on Electrical Machines and Power Electronics, ACEMP 2019 and 2019 International Conference on Optimization of Electrical and Electronic Equipment, OPTIM 2019, 27 August 2019 through 29 August 2019 ; 2019 , Pages 120-125 ; 9781538676875 (ISBN) ; Mokhtari, H ; Poshtan, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper proposes a control strategy to improve the superimposed droop frequency control scheme in DC microgrids. Conventional droop-based schemes for DC microgrids control suffer from issues such as inaccurate power sharing among the sources, voltage control with insufficient quality, and adverse effect of the line resistance on the droop characteristic. To overcome these challenges, the superimposed droop frequency method has been introduced. However, the stable operation in terms of the load variations and improper voltage quality are still the challenges with this prior-art method due to the injected AC voltages. In this paper, a method is proposed to solve the stability problem and...
Role of outage management strategy in reliability performance of multi-microgrid distribution systems
, Article IEEE Transactions on Power Systems ; 2017 ; 08858950 (ISSN) ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
Abstract
This paper develops a general framework for reliability assessment of multi-microgrid (MMG) distribution systems. It also investigates reliability impacts of coordinated outage man-agement strategies in a MMG distribution network. According to the proposed reliability evaluation framework, which is based on sequential Monte Carlo simulation method, distribution system is divided into smaller sections/microgrids based on protection sys-tem configuration and operating measures are efficiently simulat-ed considering different operation modes. In order to demonstrate the role of outage management strategy in reliability performance of MMG distribution systems, at first, the required features of...
Cooperative energy management of hybrid DC renewable grid using decentralized control strategies
, Article Energies ; Volume 9, Issue 11 , 2016 ; 19961073 (ISSN) ; Jalilvand, A ; Ehsan, M ; Sharif University of Technology
MDPI AG
2016
Abstract
This paper attempted to control a hybrid DC microgrid in islanded operation mode using decentralized power management strategies. Proposed adaptive I/V characteristic for hybrid photovoltaic (PV) and battery energy storage system (BESS) and wind turbine generator (WTG) adapts the distributed energy resources (DER) behavior independently in accordance with the load demand. Hence, the PV module can spend its maximum power on load demand and spend the extra power for charging the BESS, which will regulate DC bus voltage and maintain the power balance within the microgrid. When load demand is beyond the maximum generation power of PV unit, WTG will supply the energy shortage. The proposed...
Hierarchical power sharing control in DC microgrids
, Article Microgrid: Advanced Control Methods and Renewable Energy System Integration ; 2016 , Pages 63-100 ; 9780081012628 (ISBN) ; Mokhtari, H ; Blaabjerg, F ; Sharif University of Technology
Elsevier Inc
2016
Abstract
Because of the advances in power electronics, DC-based power systems, have been used in industrial applications such as data centers [. 18], space applications [. 10], aircraft [. 12], offshore wind farms, electric vehicles [. 56], DC home systems [. 5, 20], and high-voltage DC transmission systems. To provide such sensitive loads with more reliability, efficiency, and controllability for future power systems, AC microgrid and more recently DC microgrid and smart-grid technologies have been employed [. 5-9].To obtain stable and optimal operation in DC power systems (microgrids), proper load sharing among different energy units and acceptable voltage regulation across the microgrid is...
Optimal planning of a multi-carrier microgrid (MCMG) considering demand-side management
, Article International Journal of Renewable Energy Research ; Volume 8, Issue 1 , 2018 , Pages 238-249 ; 13090127 (ISSN) ; Jadid, S ; Ehsan, M ; Sharif University of Technology
International Journal of Renewable Energy Research
2018
Abstract
The multi-carrier microgrid (MCMG) is a restricted district comprising convertors and energy storage systems (ESSs) that are used to fulfill various energy demands. The structure and optimal operation of these MCMGs with regard to fulfilling multi-carrier demands are presented in relation to their rapid spread. In this paper, a two-stage optimum planning and design method for an MCMG is presented in the planning horizon. The investment and operation (fuel and maintenance) costs are considered concurrently to find the optimal type and size of components over the planning horizon. At the first stage, the genetic algorithm (GA) is applied to determine the optimal type and size of components,...
Incentive-Based flexible-ramp-up management in multi-microgrid distribution systems
, Article IEEE Systems Journal ; Volume 16, Issue 3 , 2022 , Pages 5011-5022 ; 19328184 (ISSN) ; Abbaspour, A ; Fotuhi Firuzabad, M ; Lehtonen, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
The increasing integration of renewable energy resources (RERs) and the expansion of multi-microgrid systems have transformed the operational condition of power systems. Respectively, the high-amount installation of RERs could result in the volatile changes exchanged-power of local systems, when their power generation drops suddenly. Nevertheless, the available ramp-up power for compensating the supply-demand gap in the power system could be limited due to the operational constraints of power networks and generation units. As a result, in this article, a transactive flexible-ramp-up-management-mechanism is offered in order to enable system operators to exploit the scheduling of microgrid...
IoT-based intelligent source–load–storage coordination scheme for prosumer campus microgrids
, Article Frontiers in Energy Research ; Volume 10 , 2022 ; 2296598X (ISSN) ; Shahzad, M ; Shehzad, M ; Akhter, J ; Almohaimeed, Z. M ; Akram, R ; Hussain, M. M ; Sharif University of Technology
Frontiers Media S.A
2022
Abstract
Electrical energy is very necessary for human life in the modern era. The rising energy prices, depletion of fossil fuels, and instability of the grid are alarming situations. So, it needs a smart solution to ensure the balance between pricing and saving natural resources. Some other issues like environmental change, limitations on installation of new transmission lines, reliability concerns, and considering the expansion in distributed energy generation technologies promise the implementation of distributed generation extensively. The integration of two or more energy supplies in a power system is known as distributed energy resource system. In this study, a university campus is taken as a...
Isolated Microgrid Planning with Solar Resource and Load Dynamics
, M.Sc. Thesis Sharif University of Technology ; Fotuhi-Firuzabad, Mahmoud (Supervisor) ; Rajabi-Ghahnavieh, Abbas (Supervisor)
Abstract
In conventional planning methods for an isolated microgrid, loads’s performance is taken into account in a constant power factor. Also, Motor loads dynamics which might results in absorbing a reactive power up to a few times more than the load’s capacity isn’t considered in this methods. Another important issue in the microgrid’s stability is the microgrid’s spinning reserve. Due to the isolated microgrid’s disconnectivity and not considering these problems in small isolated microgrids, the possibility of an instability event in microgrid’s performance would rise enourmously. In this thesis, an isolated microgrid’s planning has been carried out based on a solar resource while taking into...
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...
Control of a microgrid with unbalanced loads using virtual negative-sequence impedance loop
, Article PEDSTC 2014 - 5th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2014 , p. 78-83 ; Karimi, H ; Mokhtari, H ; Mahseredjian, J ; Sharif University of Technology
Abstract
This paper presents an effective control strategy for autonomous operation of a multi-bus medium voltage (MV) microgrid (MG) consisting of several dispatchable distributed generation (DG) units. Each electronically-coupled DG unit supplies the loads which can be unbalanced due to the inclusion of single-phase loads. The proportional resonance (PR) and droop controllers are, respectively, used to regulate the load voltage and share the average powers among the DG units. The virtual negative-sequence impedance controller (VNSIC) is proposed to effectively compensate the negative-sequence currents of the unbalanced loads. Moreover, the VNSIC minimizes the negative-sequence currents in the MV...
Distributed Primary and secondary power sharing in a droop-controlled lvdc microgrid with merged AC and DC characteristics
, Article IEEE Transactions on Smart Grid ; Volume 9, Issue 3 , 2018 , Pages 2284-2294 ; 19493053 (ISSN) ; Mokhtari, H ; Loh, P. C ; Davari, P ; Blaabjerg, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In an ac microgrid, a common frequency exists for coordinating active power sharing among droop-controlled sources. A common frequency is absent in a dc microgrid, leaving only the dc source voltages for coordinating active power sharing. That causes sharing error and poorer voltage regulation in dc microgrids, which in most cases, are solved by a secondary control layer reinforced by an extensive communication network. To avoid such an infrastructure and its accompanied complications, this paper proposes an alternative droop scheme for low-voltage dc microgrid with both primary power sharing and secondary voltage regulation merged. The main idea is to introduce a non-zero unifying frequency...