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distributed-generation--dg
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Distributed generation planning for losses, voltage profile, line congestion and total system cost improvement
, Article International Review of Electrical Engineering ; Volume 4, Issue 3 , 2009 , Pages 434-440 ; 18276660 (ISSN) ; Poure, P ; Abbaspour Tehrani fard, A ; Saadate, S ; Sharif University of Technology
2009
Abstract
The main goal of this paper is to obtain the optimal Distributed Generation (DG) investments as well as purchase additional power from Transmission Companies (TRANSCOs). To do this, a new mathematical modeling and a new software package interfacing between the two powerful softwares MATLAB and GAMS are used. The proposed model optimizes total system planning costs and consequently costumers' bills, reduces total system losses, guaranties system voltage profiles and prevents feeders' congestion. This new model and software package have been executed in two different cases depending if system voltage profiles are in their permissible margin or not; in each case, three different scenarios are...
Stability analysis and experimental evaluation of a control strategy for islanded operation of distributed generation units
, Article IEEJ Transactions on Industry Applications ; Volume 131, Issue 8 , 2011 , Pages 1013-1022 ; 09136339 (ISSN) ; Karimi, H ; Iravani, R ; Sharif University of Technology
2011
Abstract
This paper presents stability analysis of a distributed generation (DG) controller (1), in an islanded mode, based on the Mapping Theorem and the Zero Exclusion Condition, and validates the results based on a laboratory scale experimental setup. The DG unit is interfaced to the host system through a voltage-sourced converter (VSC). The control strategy regulates the load voltage at the desired value in the islanded mode, despite uncertainties in the load parameters. The frequency of the island is controlled in an open loop manner by an internal oscillator. The experimental results show that the controller provides robust voltage control for a wide range of load parameters, and even maintains...
Nondetection zone assessment of an active islanding detection method and its experimental evaluation
, Article IEEE Transactions on Power Delivery ; Volume 26, Issue 2 , 2011 , Pages 517-525 ; 08858977 (ISSN) ; Karimi, H ; Iravani, R ; Sharif University of Technology
2011
Abstract
This paper analytically determines the nondetection zone (NDZ) of an active islanding detection method, and proposes a solution to obviate the NDZ. The method actively injects a negative-sequence current through the interface voltage-sourced converter (VSC) of a distributed generation (DG) unit, as a disturbance signal for islanding detection. The estimated magnitude of the corresponding negative-sequence voltage at the PCC is used as the islanding detection signal. In this paper, based on a laboratory test system, the performance of the islanding detection method under UL1741 anti-islanding test conditions is evaluated. Then, determining the NDZ of the method and proposing the...
Stability analysis and experimental validation of a control strategy for autonomous operation of distributed generation units
, Article 2010 International Power Electronics Conference - ECCE Asia -, IPEC 2010, 21 June 2010 through 24 June 2010 ; June , 2010 , Pages 464-471 ; 9781424453955 (ISBN) ; Karimi, H ; Iravani, R ; IEEJ ; Sharif University of Technology
2010
Abstract
This paper presents stability analysis of a distributed generation (DG) controller [1], in an islanded mode, based on the Mapping Theorem and the Zero Exclusion Condition, and validates the results based on a laboratory scale experimental setup. The DG unit is interfaced to the host system through a voltage-sourced converter (VSC). The control strategy regulates the load voltage at the desired value in the islanded mode, despite uncertainties in the load parameters. The frequency of the island is controlled in an open loop manner by an internal oscillator. The experimental results show that the controller provides robust voltage control for a wide range of load parameters, and even maintains...
Developing an Framework for Efficient Usage of Distributed Generation Expansion Plans in Distribution Network Considering the Effects of Reward-Penalty Mechanism
, M.Sc. Thesis Sharif University of Technology ; Abbaspour Tehrani Fard, Ali (Supervisor)
Abstract
Based on codification and implementation of regulations of supporting from development of distributed generation sources, it is expected that in future years, investment in distributed generation scheme will be welcomed by private investors impressively. Under this circumstances, distribution Company will be faced with new chances for improving quality level of their services and optimal management of penalty-reward schemes. Penalty-reward schemes is set by legislator for distribution Company in order to improve their network. One of the pioneer ways is using distributed generators. So first, distribution Companies have to find optimum places for using these generators and in the second step...
A decentralized control method for a low-voltage dc microgrid
, Article IEEE Transactions on Energy Conversion ; Vol. 29, issue. 4 , Dec , 2014 , p. 793-801 ; 08858969 ; Ashourloo, M ; Mokhtari, H ; Sharif University of Technology
Abstract
DC microgrids (DC-MGs) are becoming popular as an effective means to integrate various renewable energy resources. Conventionally, the droop control is adopted as a decentralized control strategy for proper power sharing without using any communication link. However, the conventional droop control often deteriorates due to the effects of unequal line resistances. In this paper, a control strategy is proposed for a DC-MG to achieve perfect power sharing considering the effects of line resistances. The DC-MG under study consists of a photovoltaic system, two energy storage systems, a grid-connected converter system, and dc loads. The control strategy of the converters is addressed under...
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...
A novel optimal distribution system planning framework implementing distributed generation in a deregulated electricity market
, Article Electric Power Systems Research ; Volume 80, Issue 7 , July , 2010 , Pages 828-837 ; 03787796 (ISSN) ; Poure, P ; Abbaspour Tehrani fard, A ; Saadate, S ; Sharif University of Technology
2010
Abstract
This paper introduces a new framework included mathematical model and a new software package interfacing two powerful softwares (MATLAB and GAMS) for obtaining the optimal distributed generation (DG) capacity sizing and sitting investments with capability to simulate large distribution system planning. The proposed optimization model allows minimizing total system planning costs for DG investment, DG operation and maintenance, purchase of power by the distribution companies (DISCOs) from transmission companies (TRANSCOs) and system power losses. The proposed model provides not only the DG size and site but also the new market price as well. Three different cases depending on system...
An approach to Volt/Var control in distribution networks with distributed generation
, Article Scientia Iranica ; Volume 12, Issue 1 , 2005 , Pages 34-42 ; 10263098 (ISSN) ; Ranjbar, A. M ; Shirani, A. R ; Sharif University of Technology
Sharif University of Technology
2005
Abstract
Due to deregulation and restructuring in many countries, it is expected that the amount of small-scale generations connected to the distribution networks will increase. So, it is necessary that the impact of these kinds of generators on Volt/Var control should be investigated. This paper presents a new approach to Volt/Var control in distribution systems with Distributed Generation (DG). It has been shown that DG can improve the entire performance of a network system, by means of better control and decreasing losses. In this approach, the Genetic Algorithm (GA) has been used as the optimization method, where the amount of DG and its controlling parameters, the voltage regulators situation,...
U-shaped energy loss curves utilization for distributed generation optimization in distribution networks
, Article Journal of Zhejiang University: Science C ; Volume 14, Issue 11 , 2013 , Pages 887-898 ; 18691951 (ISSN) ; Ehsan, M ; Nouri, H ; Sharif University of Technology
2013
Abstract
We propose novel techniques to find the optimal location, size, and power factor of distributed generation (DG) to achieve the maximum loss reduction for distribution networks. Determining the optimal DG location and size is achieved simultaneously using the energy loss curves technique for a pre-selected power factor that gives the best DG operation. Based on the network's total load demand, four DG sizes are selected. They are used to form energy loss curves for each bus and then for determining the optimal DG options. The study shows that by defining the energy loss minimization as the objective function, the time-varying load demand significantly affects the sizing of DG resources in...
A robust two-degree-of-freedom control strategy for an islanded microgrid
, Article IEEE Transactions on Power Delivery ; Volume 28, Issue 3 , 2013 , Pages 1339-1347 ; 08858977 (ISSN) ; Karimi, H ; Sharif University of Technology
2013
Abstract
This paper presents a new robust control strategy for an islanded microgrid in the presence of load unmodeled dynamics. The microgrid consists of parallel connection of several electronically interfaced distributed generation units and a local load. The load is parametrically uncertain and topologically unknown and, thus, is the source of unmodeled dynamics. The objective is to design a robust controller to regulate the load voltage in the presence of unmodeled dynamics. To achieve the objective, the problem is first characterized by a two-degree-of-freedom (2DOF) feedback-feedforward controller. The 2DOF control design problem is then transformed to a nonconvex optimization problem....
Optimal siting of DG units in power systems from a probabilistic multi-objective optimization perspective
, Article International Journal of Electrical Power and Energy Systems ; Volume 51 , 2013 , Pages 14-26 ; 01420615 (ISSN) ; Hosseini, S. H ; Moeini Aghtaie, M ; Arabali, A ; Sharif University of Technology
2013
Abstract
Along with the increasing demand for electrical power, distributed generations (DGs) have so far found their pivotal roles in the restructured environment of power distribution systems. As an indispensable step toward a more reliable power system, the DGs optimal allocation strategy, deemed to be the most techno-economically efficient scheme, comes to the play and is profoundly taken under concentration in this study. This paper devises a comprehensive multi-objective (MO) optimization approach by which all the crucial and maybe contradictory aspects of great influence in the placement process can be accounted for. Total imposed costs, total network losses, customer outage costs as well as...
Optimal DG sizing in primary distribution feeders using dynamic programming approach
, Article 2012 11th International Conference on Environment and Electrical Engineering, EEEIC 2012 - Conference Proceedings, 18 May 2012 through 25 May 2012, Venice ; 2012 , Pages 371-375 ; 9781457718281 (ISBN) ; Kenari, M. T ; Mehrasa, M ; Sharif University of Technology
IEEE
2012
Abstract
Distributed generation (DG) corresponds to the application of small generating units which are the set up in distribution systems or near load centers. Utilization of DG influences various operational indices of the distribution feeders such as feeder loading, electrical losses and voltage profile. In addition, use of DG in its appropriate size is an essential tool to attain the DG maximum potential advantages. In this paper, an optimization method is proposed to determine the optimal size of DG in the distribution system. This method considers the system technical factors such as losses, voltage profile and loading of the primary distribution system feeders. The optimization process is...
Optimal distributed generation placement in a restructured environment via a multi-objective optimization approach
, Article 16th Electrical Power Distribution Conference, EPDC 2011, 19 April 2011 through 20 April 2011 ; April , 2011 , Page(s): 1 - 6 ; 9789644631498 (ISBN) ; Dehghanian, P ; Hosseini, S. H ; Sharif University of Technology
2011
Abstract
The increasing use of electrical energy in nowadays modern societies and industries has brought about a sharp need for more efficient means of electricity generation. It seems rather logical to increase the electricity production proportional to the increasing rate of the demand. Distributed Generation (DG) has been recently accepted to be one of the most efficient means of electricity generation, particularly near to the load centers. The DG has been also considered in the generation expansion planning of power systems. In this paper, three main factors associated with the DGs placement procedure is scrutinized through a multi-objective optimization approach. One of the main factors...
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...
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,...
A multistage model for distribution expansion planning with distributed generation in a deregulated electricity market
, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 34, Issue 3 , 2010 , Pages 275-287 ; 10286284 (ISSN) ; Abbaspour Tehrani Fard, A ; Poure, P ; Saadate, S ; Sharif University of Technology
2010
Abstract
Distribution systems management is becoming an increasingly complicated issue due to the introduction of new technologies, new energy trading strategies and a new deregulated environment. In the new deregulated energy market and considering the incentives coming from the technical and economic fields, it is reasonable to consider Distributed Generation (DG) as a viable option for systems reinforcement in competition with voltage regulator devices, to solve the lacking electric power supply problem and meet the load growth requirements with a reasonable price as well as the system power quality problems. The problem of optimal placement and size is formulated in two stages; minimization of...
A bi-level approach for optimal contract pricing of independent dispatchable DG units in distribution networks
, Article International Transactions on Electrical Energy Systems ; Volume 26, Issue 8 , 2016 , Pages 1685-1704 ; 20507038 (ISSN) ; Rajabi Ghahnavieh, A ; Haghighat, H ; Sharif University of Technology
John Wiley and Sons Ltd
2016
Abstract
Distributed generation (DG) units are increasingly installed in the power systems. Distribution companies (DisCo) can opt to purchase the electricity from DG in an energy purchase contract to supply the customer demand and reduce energy loss. This paper proposes a framework for optimal contract pricing of independent dispatchable DG units considering competition among them. While DG units tend to increase their profit from the energy purchase contract, DisCo minimizes the demand supply cost. Multi-leader follower game theory concept is used to analyze the situation in which competing DG units offer the energy price to DisCo and DisCo determines the DG generation. A bi-level approach is used...
A novel hybrid islanding detection method for inverter-based DGs using SFS and rOCOF
, Article IEEE Transactions on Power Delivery ; Volume 32, Issue 5 , 2017 , Pages 2162-2170 ; 08858977 (ISSN) ; Vahedi, H ; Khazaeli, F ; Oraee, H ; Sharif University of Technology
Abstract
This paper is aimed at proposing a new hybrid method for the islanding detection of distributed-generation (DG) units. Hybrid method operation is based on the combination of an active and a passive method, for which the optimized Sandia frequency shift (SFS) method is used as the selected active method, and rate of change of frequency relay (ROCOF) is used as the passive method. In order to demonstrate the effectiveness of the proposed technique on islanding detection, several simulation studies based on IEEE 1547 and UL1741 anti-islanding test requirements are carried out. The evaluation of simulation results reveals that the control system, based on the proposed hybrid algorithm, meets the...
A comprehensive digital protection scheme for low-voltage microgrids with inverter-based and conventional distributed generations
, Article IEEE Transactions on Power Delivery ; Volume 32, Issue 1 , 2017 , Pages 441-452 ; 08858977 (ISSN) ; Parniani, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Microgrid (MG) protection is one of the main challenges in proliferation of microgrids. Due to limited fault current feeding of inverter-based distributed generations (DGs), in islanded operation of MG, protection problems become more complicated; and, therefore, conventional protection strategies cannot be applied. Hence, new protection methods that are applicable in islanded and grid-connected modes of operation are necessary. In this paper, a comprehensive digital-relay based protection is introduced for the protection of MGs. The proposed method includes protection of lines, distributed generations, and the point of common coupling. The structure and graphical schematic of the proposed...