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distributed-generation
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μ-Synthesis control for an islanded microgrid with structured uncertainties
, Article IECON Proceedings (Industrial Electronics Conference), 7 November 2011 through 10 November 2011 ; November , 2011 , Pages 3064-3069 ; 9781612849720 (ISBN) ; Karimi, H ; Sharif University of Technology
2011
Abstract
This paper presents a robust control scheme for an islanded microgrid in the presence of structured uncertainties. The microgrid consists of parallel connection of two Distributed Generation (DG) units and a passive load. The DG units are connected to the passive load by using the power electronics converters. The microgrid model is structurally uncertain due to the large perturbations in the load parameters. To deal with the uncertainties, a Linear Fractional Representation (LFR) of the parametrically uncertain system is obtained. To achieve robust performance, the μ-synthesis approach is applied to the derived LFR model to design a μ controller. The resultant controller is structurally...
Voltnar control in distribution networks with distributed generation
, Article 5th IFAC Symposium on Power Plants and Power Systems Control 2003, 15 September 2003 through 19 September 2003 ; Volume 36, Issue 20 , 2003 , Pages 547-552 ; 14746670 (ISSN) ; Ranjbar, A. M ; Shirane, A. R ; Sharif University of Technology
IFAC Secretariat
2003
Abstract
Due to the deregulation and restructuring in many countries, it is expected that amount of small-scale generations connected to the distribution networks increase. So it is necessary that impact of these kinds ofgenerators on VoltNar control would be investigated. This paper presents a new approach for VoltNar control in distribution system with Distributed Generation (DG) and it has shown that DG can improve the entire performance of network, by means of better controlling of the system and decreasing losses in network. In this approach Genetic Algorithm (GA) has been used as the optimization method where the amount of Dispersed Generation and its controlling parameters, Voltage regulators...
Voltage regulation through smart utilization of potential reactive power resources
, Article Proceedings - UKSim 5th European Modelling Symposium on Computer Modelling and Simulation, EMS 2011, 16 November 2011 through 18 November 2011, Madrid ; 2011 , Pages 293-298 ; 9780769546193 (ISBN) ; Abbaspour Tehrani Fard, A ; Dobakhshari, A. S ; Ranjbar, A. M ; Sharif University of Technology
Abstract
The introduction of demand response concept, in addition to increment of penetration of distributed generation (DG) based on renewable energies, make opportunities for the novel control schemes to be integrated in power system on a smart grid framework. Voltage control methods in power systems needs proper coordination among reactive power resources and conventional volt/var control equipments. In this work, potential reactive power resources are investigated and then, reactive power output of renewable DG units and controllable loads along with operation of conventional voltage controllers are optimized using a centralized control scheme. Considering the variability of demand and...
Voltage and frequency consensusability of autonomous microgrids over fading channels
, Article IEEE Transactions on Energy Conversion ; Volume 36, Issue 1 , 2021 , Pages 149-158 ; 08858969 (ISSN) ; Khorsandi, A ; Baghaee, H. R ; Sadati, N ; Shirvani Moghaddam, S ; Guerrero, J. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In this article, a novel cooperative secondary voltage/frequency control considering time-varying delays and noises in fading channels is presented for an autonomous alternating current (AC) voltage sourced-based converter (VSC)-based microgrid (MG), including inverter-interfaced distributed generations (DGs). Fading phenomenon makes complex random fluctuations on the voltage and frequency of every DG received from its neighbor DGs. In multi-agent cooperative systems, in addition to the total additive noise and time-variant delay, a multiplicative complex random variable is considered to model the main received signal and its replicas due to multipath propagation. The proposed...
Using genetic alghoritm for distributed generation allocation to reduce losses and improve voltage profile
, Article 42nd International Universities Power Engineering Conference, UPEC 2007, Brighton, 4 September 2007 through 6 September 2007 ; 2007 , Pages 954-959 ; 1905593368 (ISBN); 9781905593361 (ISBN) ; Sedighizadeh, M ; Bayat, M. R ; Khodayar, M. E ; Sharif University of Technology
2007
Abstract
This paper presents a method for the optimal allocation of Distributed generation in distribution systems. In this paper, our aim would be optimal distributed generation allocation for voltage profile improvement and loss reduction in distribution network. Genetic Algorithm (GA) was used as the solving tool, which referring two determined aim; the problem is defined and objective function is introduced. Considering to fitness values sensitivity in genetic algorithm process, there is needed to apply load flow for decision-making. Load flow algorithm is combined appropriately with GA, till access to acceptable results of this operation. We used MATPOWER package for load flow algorithm and...
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...
Transmission congestion management using distributed generation considering load uncertainty
, Article Asia-Pacific Power and Energy Engineering Conference, APPEEC, 28 March 2010 through 31 March 2010 ; March , 2010 ; 21574839 (ISSN) ; 9781424448135 (ISBN) ; Noory, A. R ; Abbaspour T. F., A ; Rashidinejad, M ; Sharif University of Technology
2010
Abstract
This Paper presents a model for optimal locating and sizing of Distributed Generation (DG) for congestion management in deregulated electricity market. For reducing the solution space a priority list of candidate buses is formed and then optimal placement and sizing of DG in potential buses is discussed. In order to incorporate stochastic nature of power system in this study, Monte-Carlo method is used to simulate the effect of uncertainty of loads and system on the optimal location and size of the DGs in the network. The proposed method is applied to IEEE Reliability Test System (RTS). The impacts of load uncertainty on optimum DG size and location are studied
Toward small scale renewable energy hub-based hybrid fuel stations: appraising structure and scheduling
, Article IEEE Transactions on Transportation Electrification ; Volume 6, Issue 1 , 2020 , Pages 267-277 ; Alahyari, A ; Farrokhifar, M ; Momeni, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
In recent years, there has been a rapid change in the portfolio of road vehicles. This transformation needs to be supported by reshaping fuel stations. The existing structures can be modified to supply multiple vehicle types while utilizing renewable energies. In this article, we introduce a hybrid fuel station (HFS) to supply both electric and natural gas vehicles. We incorporate an energy hub and thoroughly explain the structure and components in detail. The configuration of the proposed HFS includes renewable energy sources (RESs), a power-to-gas unit (P2G), a natural gas distributed generator (NGDG), an energy storage device, a compressor, and a gas storage device. The optimal operation...
The effects of excitation control systems on parallel operation of DG with the main grid
, Article International Journal of Power and Energy Systems ; Volume 28, Issue 4 , 2008 , Pages 438-447 ; 10783466 (ISSN) ; Parniani, M ; Rasouli, M ; Sharif University of Technology
2008
Abstract
This paper presents actual cases of steady reactive power oscillation of distributed generations (DGs) during parallel operation with the main grid. The cause of the problem was found to be the adverse effects of excitation system voltage regulation. It is shown, through preliminary investigation and detailed simulation studies, that how the excitation control system can be modified to overcome this problem. On-site test results verify the analysis results and effectiveness of the remedial actions. Finally, general practical recommendations are offered for excitation control of synchronous generator-based DG, such that it performs properly, both in grid connected and in islanding conditions
Sustainable solutions for advanced energy management system of campus microgrids: model opportunities and future challenges
, Article Sensors ; Volume 22, Issue 6 , 2022 ; 14248220 (ISSN) ; Javed, H ; Akhter, M. N ; Shahzad, M ; Munir, H. M ; Nadeem, M. U ; Bukhari, S. S. H ; Huba, M ; Sharif University of Technology
MDPI
2022
Abstract
Distributed generation connected with AC, DC, or hybrid loads and energy storage systems is known as a microgrid. Campus microgrids are an important load type. A university campus microgrids, usually, contains distributed generation resources, energy storage, and electric vehicles. The main aim of the microgrid is to provide sustainable, economical energy, and a reliable system. The advanced energy management system (AEMS) provides a smooth energy flow to the microgrid. Over the last few years, many studies were carried out to review various aspects such as energy sustainability, demand response strategies, control systems, energy management systems with different types of optimization...
Stochastic modeling of the energy supply system with uncertain fuel price - A case of emerging technologies for distributed power generation
, Article Applied Energy ; Volume 93 , 2012 , Pages 668-674 ; 03062619 (ISSN) ; Saboohi, Y ; Sharif University of Technology
2012
Abstract
A deterministic energy supply model with bottom-up structure has limited capability in handling the uncertainties. To enhance the applicability of such a model in an uncertain environment two main issues have been investigated in the present paper. First, a binomial lattice is generated based on the stochastic nature of the source of uncertainty. Second, an energy system model (ESM) has been reformulated as a multistage stochastic problem. The result of the application of the modified energy model encompasses all uncertain outcomes together and enables optimal timing of capacity expansion. The performance of the model has been demonstrated with the help of a case study. The case study has...
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...
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...
Scheduling and sizing of campus microgrid considering demand response and economic analysis
, Article Sensors ; Volume 22, Issue 16 , 2022 ; 14248220 (ISSN) ; Shahzad, M ; Javed, H ; Muqeet, H. A ; Akhter, M. N ; Liaqat, R ; Hussain, M. M ; Sharif University of Technology
MDPI
2022
Abstract
Current energy systems face multiple problems related to inflation in energy prices, reduction of fossil fuels, and greenhouse gas emissions which are disturbing the comfort zone of energy consumers and the affordability of power for large commercial customers. These kinds of problems can be alleviated with the help of optimal planning of demand response policies and with distributed generators in the distribution system. The objective of this article is to give a strategic proposition of an energy management system for a campus microgrid (µG) to minimize the operating costs and to increase the self-consuming energy of the green distributed generators (DGs). To this end, a real-time based...
Robust tuning of transient droop gains based on kharitonov's stability theorem in droopcontrolled microgrids
, Article IET Generation, Transmission and Distribution ; Volume 12, Issue 14 , 2018 , Pages 3495-3501 ; 17518687 (ISSN) ; Sadati, N ; Hamzeh, M ; Sharif University of Technology
Abstract
This study addresses the robust stability analysis for an islanded microgrid with droop-controlled inverter-based distributed generators (DGs). Owing to large load changes, microgrid structure reconfiguration, and higher-power demands, the low-frequency (LF) dominant modes of a microgrid stir toward unstable zone and make the system more oscillatory or even unstable. In this study, a robust two-degree-of-freedom (2DOF) decentralised droop controller, which is the combination of the conventional droop with a robust transient droop function, is utilised for each inverter-based DG unit. Unlike conventional tuning of 2DOF droop controllers, a new design procedure is proposed to robustly...
Robust restoration of distribution systems considering DG units and direct load control programs
, Article Turkish Journal of Electrical Engineering and Computer Sciences ; Volume 26, Issue 5 , 2018 , Pages 2676-2687 ; 13000632 (ISSN) ; Fotuhi Firuzabad, M ; Sharif University of Technology
Turkiye Klinikleri Journal of Medical Sciences
2018
Abstract
This paper presents a new method for restoration of distribution networks after a fault occurrence. This problem is solved from the viewpoint of the distribution system operator with the main goal of minimizing the operating cost during the fault clearance period. The effects of distributed generation (DG) units and direct load control (DLC) programs are considered in designing the proposed restoration procedure. Moreover, the uncertainties associated with the predicted loads of different nodes and the availability of DG are modeled here. Robust optimization is used to model the uncertainties of restoration problems and manage their associated risks. Finally, a robust reconfiguration plan is...
Robust decomposition and structured control of an islanded multi-DG microgrid
, Article IEEE Transactions on Smart Grid ; 2018 ; 19493053 (ISSN) ; Nobakhti, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
This paper presents a new robust control strategy for islanded operation of a microgrid consisting of several distributed generation (DG) units with arbitrary topology. Each DG unit is connected to its local load through a voltage-source converter (VSC), a series RL filter and a step-up transformer. The multi-DG microgrid with arbitrary connectivity graph is modeled as a linear time-invariant (LTI) system subject to a parametric, norm-bounded uncertain block. By utilizing the developed model for multi-DG microgrids, a systematic approach for the design of structured dynamic output feedback control is proposed. A convex optimization problem is developed which yields a low-order dynamic...
Robust decomposition and structured control of an islanded multi-DG microgrid
, Article IEEE Transactions on Smart Grid ; Volume 10, Issue 3 , 2019 , Pages 2463-2474 ; 19493053 (ISSN) ; Nobakhti, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper presents a new robust control strategy for islanded operation of a microgrid consisting of several distributed generation (DG) units with arbitrary topology. Each DG unit is connected to its local load through a voltage-source converter, a series RL filter and a step-up transformer. The multi-DG microgrid with arbitrary connectivity graph is modeled as a linear time-invariant system subject to a parametric, norm-bounded uncertain block. By utilizing the developed model for multi-DG microgrids, a systematic approach for the design of structured dynamic output feedback control is proposed. A convex optimization problem is developed which yields a low-order dynamic controller of...
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,...
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...