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distributed-generation
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Optimal allocation of distributed generation using a two-stage multi-objective mixed-integer-nonlinear programming
, Article European Transactions on Electrical Power ; Volume 21, Issue 1 , 2011 , Pages 1072-1087 ; 1430144X (ISSN) ; Poure, P ; Abbaspour Tehrani Fard, A ; Saadate, S ; Sharif University of Technology
Abstract
Cost is one of the most essential factors that influence many decisions taken in the distribution system planning. In general, cost can be defined as everything that should be sacrificed to gain the desired results. This paper proposes a new two-stage methodology for distributed generation (DG) placement as an attractive option for distribution system planner. This method aims to minimize cost and maximize total system benefit (TSB). Optimal placement and size are obtained from total cost minimization mathematical problem which is solved in the first stage. For each DG cost characteristics and for each investment payback time, there is an optimal location and size. Then the optimal DG...
Robust control of an autonomous four-wire electronically-coupled distributed generation unit
, Article IEEE Transactions on Power Delivery ; Volume 26, Issue 1 , September , 2011 , Pages 455-466 ; 08858977 (ISSN) ; Yazdani, A ; Iravani, R ; Sharif University of Technology
2011
Abstract
This paper proposes a control strategy for the autonomous (islanded) operation of a four-wire, electronically-coupled distributed generation (DG) unit which can feed a highly unbalanced load, e.g., due to the presence of single-phase loads. In the grid-connected mode, the power-electronic interface of the DG unit enables the exchange of real and reactive power with the distribution network, based on the conventional dq-frame current control strategy. The current control scheme is disabled subsequent to the detection of an islanding event, and the proposed controller is activated. The proposed control strategy utilizes: i) an internal oscillator to maintain the island frequency and ii) a...
A practical eco-environmental distribution network planning model including fuel cells and non-renewable distributed energy resources
, Article Renewable Energy ; Volume 36, Issue 1 , 2011 , Pages 179-188 ; 09601481 (ISSN) ; Ehsan, M ; Zareipour, H ; Sharif University of Technology
Abstract
This paper presents a long-term dynamic multi-objective planning model for distribution network expansion along with distributed energy options. The proposed model optimizes two objectives, namely costs and emissions and determines the optimal schemes of sizing, placement and specially the dynamics (i.e., timing) of investments on distributed generation units and network reinforcements over the planning period. An efficient two-stage heuristic method is proposed to solve the formulated planning problem. The effectiveness of the proposed model is demonstrated by applying it to a distribution network and comparing the simulation results with other methods and models
A possibilistic-probabilistic tool for evaluating the impact of stochastic renewable and controllable power generation on energy losses in distribution networks-A case study
, Article Renewable and Sustainable Energy Reviews ; Volume 15, Issue 1 , 2011 , Pages 794-800 ; 13640321 (ISSN) ; Ehsan, M ; Sharif University of Technology
Abstract
This paper proposes a hybrid possibilistic-probabilistic evaluation tool for analyzing the effect of uncertain power production of distributed generations (DGs) on active losses of distribution networks. The considered DG technologies are gas and wind turbines. This tool is useful for distribution network operators (DNOs) when they are faced with uncertainties which some of them can be modeled probabilistically and some of them are described possibilistically. The generation pattern of DG units changes the flow of lines and this will cause change of active losses which DNO is responsible for compensating it. This pattern is highly dependent on DG technology and also on decisions of DG...
Financial tools to manage dispatchable Distributed Generation economic risks
, Article International Conference on Smart Energy Grid Engineering, SEGE 2015, 17 August 2015 through 19 August 2015 ; 2015 ; 9781467379328 (ISBN) ; Rajabi-Ghahnavieh, A ; Azad, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Distributed Generation (DG) has received increasing attention during the last decade. Advantage and constraints of DG application are well known to both DG owner and electric utility. Various technologies are available for DG units among them gas GenSet is, in particular, more attractive to the investors as the technology provides the control on DG generation. However, there are various financial risks associated with dispatchable DG units that prohibit wide private investment in such technologies. This paper examines the use of financial tools to manage dispatchable DG economic risks. A comprehensive framework has been proposed to consider various economic risks to DG owner. Suitable models...
Improvement of Power Sharing In Microgrids Consist of Synchronous Generators and Converter Based Distributed Generation Units
, M.Sc. Thesis Sharif University of Technology ; Mokhtari, Hossein (Supervisor)
Abstract
This dissertation studies the operation of the power sharing system in a micro-grid (MG) which includes a synchronous generator and the converter based distributed generation (DG) units. Increasing advent of MGs and the huge penetration of DGs to the existing power systems require comprehensive studies on the interactions between synchronous generators and converter based DGs for the sharing of power during and after the occurrence of different disturbances such as load changing. Thus, this project discusses existing control methods which can be used to share the power between a synchronous generator and converter based DGs. Then, a new control strategy is proposed in order to enhance the...
Optimal Distributed Generation Allocation and Sizing Considering Operation Indices
, M.Sc. Thesis Sharif University of Technology ; Mokhtari, Hossein (Supervisor)
Abstract
The need for independent power generation has been increased in recent years with the growing demand in micro grid systems. Losses in power systems are unavoidable. These losses occur in transmission to distributionnetworks from the generation sites to the end-user loads. Reduction of power losses has been one of the reasons for engineers to be attracted by micro grid systems which include small size independent power generation units. However, in a micro grid with several DGs of different types and with all kinds of loads of variable nature, an optimal power balance in the system has to be achieved. This optimal objective, which results in minimal energy losses over a specific period of...
Technical and Economic Aspects of Operating of Distribution Systems in Presence of Distributed Generation Considering the Uncertainties
, M.Sc. Thesis Sharif University of Technology ; Ehsan, Mehdi (Supervisor)
Abstract
As electric energy loss in Iran is around 31 percent and 01 percent of this loss is related to the distribution of electric energy, management and operation of distribution network is of high importance. There are different ways for operating the distribution network while decreasing the loss, such as using capacitors, tap changers, energy storing devices, distributed generations, etc. One of the most common ways is to use Network Reconfiguration. In this thesis, daily reconfiguration of a 03-kV 22-bus distribution network is investigated. The objective function consists of cost of energy loss and improvement of voltage profile. Wind turbines are used as the sources of distributed generation...
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...
Improvement of Control of Hybrid AC-DC Microgrid in Islanded Mode
, Ph.D. Dissertation Sharif University of Technology ; Mokhtari, Hossein (Supervisor)
Abstract
A microgrid is a collection of loads, sources, and power storage units that operates as a single controllable system and can operate in grid-connected or islanded mode. From the generating side, renewable energy resources such as photovoltaic system, fuel cell and power storage units are inherently DC. From the load side, electronic loads such as computers, data centers and most of the variable speed motor drives require a DC supply. Therefore, DC Microgrids have gained widespread attention in recent years. On the other hand, since existing distribution systems are mostly AC, a hybrid microgrid is more likely. The hybrid microgrid is composed of two AC and DC subgrids interlinked by power...
Nonlinear adaptive control of grid-connected three-phase inverters for renewable energy applications
, Article International Journal of Control ; 2015 ; 00207179 (ISSN) ; Namvar, M ; Karimi, H ; Piya, P ; Karimi Ghartemani, M ; Sharif University of Technology
Abstract
Distributed generation (DG) units are often interfaced to the main grid using power electronic converters including voltage-source converters (VSCs). A VSC offers dc/ac power conversion, high controllability, and fast dynamic response. Because of nonlinearities, uncertainties, and system parameters’ changes involved in the nature of a grid-connected renewable DG system, conventional linear control methods cannot completely and efficiently address all control objectives. In this paper, a nonlinear adaptive control scheme based on adaptive backstepping strategy is presented to control the operation of a grid-connected renewable DG unit. As compared to the popular vector control technique, the...
Benefits of real-time monitoring to distribution systems: dynamic thermal rating
, Article IEEE Transactions on Smart Grid ; Volume 6, Issue 4 , 2015 , Pages 2023-2031 ; 19493053 (ISSN) ; Degefa, M. Z ; Fotuhi Firuzabad, M ; Lehtonen, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
With anticipated proliferation of electric vehicles and distributed generations in near future, dynamic thermal rating (DTR) as a tool for unlocking network capacities, is becoming critical for distribution network operators. DTR is gaining a great and still growing focus of attention in today's power industries. However, potential benefits of DTR, although have been envisioned to be significant, have not yet been studied quantitatively. This paper intends to comprehensively assess the potential impacts of DTR on the performance of a realistic Finnish distribution network. For doing so, first a step-by-step procedure is devised. Then, weather data and loading information of circuits in the...
Automatic image annotation using semi-supervised generative modeling
, Article Pattern Recognition ; Volume 48, Issue 1 , January , 2015 , Pages 174-188 ; 00313203 (ISSN) ; Jamzad, M ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Image annotation approaches need an annotated dataset to learn a model for the relation between images and words. Unfortunately, preparing a labeled dataset is highly time consuming and expensive. In this work, we describe the development of an annotation system in semi-supervised learning framework which by incorporating unlabeled images into training phase reduces the system demand to labeled images. Our approach constructs a generative model for each semantic class in two main steps. First, based on Gamma distribution, a generative model is constructed for each semantic class using labeled images in that class. The second step incorporates the unlabeled images by using a modified EM...
Planning and Optimization of an On-site Energy Service Network for a Rural Region
, M.Sc. Thesis Sharif University of Technology ; Avami, Akram (Supervisor)
Abstract
Nowadays, classic energy supply systems are rapidly shifting towards more efficient, with less pollution, and more economic energy systems. In the meantime, the growing dependence of human activities on energy sources and the reduction of fossil fuels resources as the main source of energy supply at present time, has led to fundamental changes in the energy policy of communities. The use of distributed power generation systems utilizing renewable energy sources is one of the solutions that have been proposed in this regard. This research aims to develop a local energy supply network for a specific rural district using energy sources in place, so that the area is energy self-sufficient and...
Relay logic for islanding detection in active distribution systems
, Article IET Generation, Transmission and Distribution ; Volume 9, Issue 12 , August , 2015 , Pages 1254-1263 ; 17518687 (ISSN) ; Amraee, T ; Ranjbar, A. M ; Mozafari, B ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
This study presents a passive model to detect islanding conditions of synchronous distributed generation resources in a distribution network or a microgrid. The proposed approach uses the classification and regression tree algorithm for distinguishing between islanding and non-islanding situations. It utilises the rate of change of frequency (ROCOF) and harmonic content of the equivalent reactance seen at the location of distributed generation as input features for decision tree construction. Indeed the thresholds of the proposed input features are extracted by the decision tree algorithm. The output if-then rules of the decision tree algorithm are then utilised to make a new relay logic for...
Robust decentralized control for islanded operation of two radially connected DG systems
, Article 2010 IEEE International Symposium on Industrial Electronics, ISIE 2010, Bari, 4 July 2010 through 7 July 2010 ; July , 2010 , Pages 2272-2277 ; 9781424463916 (ISBN) ; Karimi, H ; Karimi Ghartemani, M ; The Institute of Electrical and Electronics Engineers (IEEE); IEEE Industrial Electronics Society (IES); IEEE Control Systems Society (CSS); Society of Instrument and Control Engineers (SICE-Japan); Politecnico di Bari ; Sharif University of Technology
2010
Abstract
A decentralized servomechanism controller for islanded (autonomous) operation of radial connection of two distributed generation (DG) units is proposed in this paper. Each DG unit utilizes a voltage-sourced converter (VSC) for interface to its dedicated load. The DG units and the loads are to operate in the islanded mode of operation. Each DG unit regulates the voltage of its dedicated load in a decentralized manner. In this paper, it is first shown that the radial connection of two DG units in the islanded mode constitutes an interconnected composite system consisting of two subsystems. Moreover, the paper shows that the overall islanded system can be controlled by the local controllers,...
Modeling, control and islanding detection of microgrids with passive loads
, Article Proceedings of EPE-PEMC 2010 - 14th International Power Electronics and Motion Control Conference, 6 September 2010 through 8 September 2010 ; September , 2010 , Pages T11107-T11112 ; 9781424478545 (ISBN) ; Karimi, H ; Nikkhajoei, H ; Terzija, V ; Sharif University of Technology
2010
Abstract
This paper presents a control scheme for microgrids with passive loads. The existing control techniques for distributed generation systems are designed to operate either in the grid-connected or in the islanded mode. In the grid-connected mode of operation, a currentcontrolled scheme based on d-q variables is used for the regulation of real and reactive powers of the converter. In the islanded mode of operation, the converter is controlled in the voltage-controlled mode. This paper deals with the modeling of both control schemes. Furthermore, reconnection from the islanded mode to the grid-connected mode based on the use of adequate Phase-Locked Loops (PLLs) has been demonstrated
Optimal placement and sizing of distributed resources for congestion management considering cost/benefit analysis
, Article IEEE PES General Meeting, PES 2010, 25 July 2010 through 29 July 2010, Minneapolis, MN ; 2010 ; 9781424483570 (ISBN) ; Abbaspour Tehrani Fard, A ; Rashidinejad, M ; Lee, K. Y ; Sharif University of Technology
2010
Abstract
Congestion management is one of the most important issues for secure and reliable system operations in deregulated electricity market. This paper presents a cost/worth analysis approach for optimal location and sizing of Distributed Resources (DRs) to mitigate congestion and increase security of the system. In order to reduce the solution space a priority of candidate buses is formed, then optimal location and sizing problem is discussed. To increase the accuracy of results, load duration curve is constituted and based on this curve different load levels are incorporated into this study. Proposed method considers economical factors such as congestion rent, deferred upgrading investment and...
Competitive distribution system planning model integration of dg, interruptible load and voltage regulator devices
, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 34, Issue 6 , 2010 , Pages 619-635 ; 10286284 (ISSN) ; Porkar, S ; Abbaspour Tehrani Fard, A ; Poure, P ; Saadate, S ; Sharif University of Technology
Abstract
Distribution systems management is becoming an increasingly complicated issue due to the introduction of new technologies, new energy trading strategies, and new deregulated environment. In the new deregulated energy market and considering the incentives coming from the technical and economical fields, it is reasonable to consider Distributed Generation (DG) as a viable option to solve the lacking electric power supply problem. This paper presents a mathematical distribution system planning model considering three planning options to system expansion and to meet the load growth requirements with a reasonable price as well as the system power quality problems. DG is introduced as an...
A new framework for large distribution system optimal planning in a competitive electricity market
, Article 2010 IEEE International Energy Conference and Exhibition, EnergyCon 2010, 18 December 2010 through 22 December 2010 ; 2010 , Pages 1-6 ; 9781424493807 (ISBN) ; Poure, P ; Abbaspour Tehrani Fard, A ; Saadate, S ; Sharif University of Technology
Abstract
Distribution systems management is becoming an increasingly complicated issue due to the introduction of new technologies, new energy trading strategies and new deregulated environment. In the new deregulated energy market and considering the incentives coming from the technical and economical fields, it is reasonable to consider Distributed Generation (DG) as a viable option to solve the lacking electric power supply problem. This paper presents a mathematical distribution system planning model considering three planning options to system expansion and to meet the load growth requirements with a reasonable price as well as the system power quality problems. DG is introduced as an attractive...