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Showing 9 results for Microgrid
Mr. Babak Rashidi Pour , Dr. Hossein Haroonabadi ,
Volume 1, Issue 3 (3-2013)
Abstract
In today's electric grid, due to demand growth, environmental issues and limited energy resources, distributed energy resources (DERs) application and demand-side management methods have received special attention. High penetration of DERs and implementation of demand response (DR) programs, especially in distribution networks, have affected several issues on these networks such as their control and operation. Although DERs can reduce the required network operation and planning costs, control and operation of a large number of DERs with different characteristics is a major challenge for the secure and efficient operation of power system. This challenge is introducing a new concept as microgrid which is a MV/LV grid with embedded DERs interconnected with the upstream grid to exchange thesurplus or deficit of electrical power locally produced respect to the load. Therefore, according to the key role of distribution networks in restructured environment, optimal energy management in this new environment requires considerable research. Due to these reasons, this thesis presents a comprehensive energy management framework for an active distribution network considering high penetration of distributed energy resources and demand response programs. In the proposed model, microgrid maximizes its profit by participating in energy and reserve markets and selling energy to its end-use customers; this is achieved by optimal scheduling of its internal resources during 24 hours time horizon. The proposed method can assess various DERs (both dispatchable and non-dispatchable units) along with their technical and economical constraints. It also considers distribution network security constraints, the possibility of power exchange with the neighboring microgrid, and uncertainties associated with renewable production and load pattern.
Also, a real-time pricing (RTP) in a smart grid environment is presented. Using the RTP, microgrid maximizes its profit considering customers’ benefit. This pricing scheme could be used as an efficient tool to manage customers’ energy consumption and distribution grid operation costs. Finally, a comprehensive model for energy management in an active distribution network in presence of DERs and proposed pricing scheme is presented in order to participate in energy and reserve markets. The proposed model is a mixed-integer nonlinear programming (MINLP) problem which is solved in GAMS software using DICOPT solver. A 32-bus distribution network including dispatchable generators, electric energy storage, wind turbine units, interruptible loads, and interties is used to evaluate the effectiveness and feasibility of the proposed method. Numerical studies show that by applying the proposed method, in comparison with fixed electricity price tariff, the distribution companies could increase the revenue of participants by modifying the consumption pattern. Also, they can operate the distributed energy sources in distribution network more efficiently
Mortezaa Mozaffari, Dr. Ebrahim Aghajari, Dr. Mehdi Forouzanfar,
Volume 8, Issue 4 (2-2020)
Abstract
The active-frequency and reactive-voltage droop control method is one of the most widely used decentralized control methods in island-controlled microgrids. With the active-frequency droop control, it can be used to divide the exact active power between distributed energy sources, but the reactive-voltage droop, due to the high dependence on the line impedance and the load rate, often makes it worse to divide the reactive power between resources. Another challenge of the droop control is the frequency deviation and voltage mediated by load changes. In this paper, a new independent method for accurate account of reactive power between the distributed energy resources and the recovery of the micro-grid frequency has been provided. The proposed method improves the reliability and simplicity of the network. Simulation results show that the performance accuracy of the proposed method is especially about the correct splitting of reactive power and retrieval of the network frequency, as the difference in the reactive power of resources is reduced from approximately 1200 to 700 var and the network frequency is maintained on 314 radians per second.
Dr. Ali Darvish Falehi,
Volume 10, Issue 3 (12-2021)
Abstract
Currently, renewable power plants based on photovoltaic farms are considered as main sources of energy production which have been rapidly growing. However, changes in weather conditions are one of the issues facing this energy conversion system to provide the required power for the consumer. An efficient controller can appropriately control and improve the dynamic performance of the island microgrid based on the photovoltaic system. In this paper, a perturbation and observation method based on optimal fuzzy control is proposed to provide the required energy for the microgrid. In this regard, partial changes in the proportional and integral constants during the climate changes are calculated to ensure the convergence at the desired point. In order to find the desired parameters of the fuzzy system membership functions, a non-dominated sorting genetic algorithm is used. Then, the optimal duty cycle signal is injected into the boost converter. To verify and validate the performance of the proposed controller, a comparison is also made with the conventional observation and perturbation strategy. Also, different radiation conditions are considered for the under study photovoltaic system. Modeling of photovoltaic system and proposed control system has been performed by MATLAB / Simulink software. Finally, the simulation results show that the speed and accuracy of the maximum power point tracking by the proposed control system has been significantly improved.
Mahdi Abolhassan Beygi, Dr. Soodabeh Soleymani, Dr. Seyed Babak Mozafari, Dr. Reza Sharifi,
Volume 11, Issue 4 (3-2023)
Abstract
In this article, a comprehensive management plan for the operation of a multiple microgrid will be presented based on economic and environmental considerations with the formation of a coalition between microgrids with the aim of increasing the profit of microgrid operation. The proposed model is formulated as a multilevel optimization problem with a game theory approach. At the local level, the environmental and economic dual-objective optimization problem is presented for each microgrid based on distributed production and renewable energy resources. Since the problem of planning for electrical and thermal loads is applied, therefore, energy carriers such as electrical energy and fuel required by power plants are included in the optimization plan, and due to the penetration of scattered productions based on renewable energies, there is uncertainty in power. output in the microgrid, in the proposed structure, two practical tools are proposed for the optimal use of this equipment and increasing the profit of the microgrid operator, the first tool is the optimal use of energy storage resources and the second tool is responsive loads and the management plan of these loads in order to achieve The objectives of the microgrid operator will be. In this research, particle consensus algorithm as well as game theory-based modeling are used for optimization, simulation is done using Games software, and its results are implemented by implementing a collaboration space and forming a coalition between microgrids and distribution network. It has significantly reduced the final costs of the collection.
Seyede Mahsa Sarhaddi , Dr. Soodabeh Soleymani , Dr. Seyed Babak Mozaffari ,
Volume 12, Issue 3 (12-2023)
Abstract
In this paper, the resilience-oriented energy management of the multiple microgrids is followed. For this purpose, a three levelgame theory based model is developed for energy management of microgrids. In this model, the coalition between the microgrids is formed to achieve optimal cumulative energy management considering the resilience concept. In this model, at first, a bi-level problem is developed from the perspective of the central operator to determine the optimal energy trading between the upstream network and multiple microgrids. The proposed bi-level model is formulated as a mathematical program with equilibrium constraints (MPEC) problem. In the bi-level problem, an optimization problem is formulated in the upper level from the perspective of the whole coalition. Therefore, minimizing the operating cost of the entire coalition is considered as the objective function. The lower level of the problem is also modeled from the point of view of each microgrid. In order to resilience-oriented model the energy management problem, the possibility of disconnecting the coalition connection line with the upstream network is probabilistically modeled based on the scenarios. After solving the MPEC problem and determining the energy exchanges, the local microgrids are operated separately from the perspective of the local operator in the third level.In this way, the operational statues of the electrical units as well as the energy storage systems are determined.The results of the simulations show that by using the method proposed in this article, with the presence of energy storage systems, the interrupted load and also the operating cost in the resilient mode will be equal to the normal mode.Also, the studies demonstrate using the proposed three-level model, the total cost is reduced by about 5.7 for the normal mode and about 7% for the resilience mode compared to the conventional two-level model.
Dr. Iman Chaharmahali, Dr. Mohammad Jafarifar,
Volume 12, Issue 3 (12-2023)
Abstract
To evaluate the reliability of active distribution networks, there is a need to model distributed generation sources, mainly renewable ones. The traditional (common) reliability models are not able to take into account the intermittent and random nature of these energy sources, so the need for a new reliability model is necessary to model the production sources of this type of distribution network. In analytical methods, an analytical model of the network is prepared and the problem is solved mathematically; but with the complexity of the network, solving problems becomes very difficult and practically impossible. Therefore, in terms of the complexity of the structure and the variety of operating modes of active distribution networks, a simulation [Monte Carlo] method has been proposed to evaluate their reliability. In this method, all failure modes of network components are randomly classified and specified. On the other hand, by using the proposed model of reliability of DGs, the nature of randomness of these sources has been accurately considered in the simulation process. The simulation results of a sample active distribution network indicate that, with the introduction of microgrids, the reliability indicators of the network and its loads have improved, but the microgrid has had the greatest impact on the load indicators within the microgrid itself.
Mohammad Reza Ghodsi, Dr. Alireza Tavakoli, Dr. Amin Samanfar,
Volume 12, Issue 3 (12-2023)
Abstract
To deal with the challenge of the level of penetration of renewable energy sources against uncertainties and in order to develop the secondary load frequency control loop, with the aim of reducing the impact of disturbances and adjusting the resistant gain coefficient to uncertainties, using a virtual inertial controller based on the resistant control of the Mu-synthesis method. For the lack of inertia in the islanded microgrid clusters, alternating current has been done. The stability and performance of this method is proved based on the structured singular value. The experimental results of the hardware in the loop by the TMS320F2812 digital signal processor and the simulation in the MATLAB/SIMULINK software environment confirm the performance of the proposed controller for the development of traditional load frequency control in comparison with the enhanced virtual inertial control and inertialess mode, under various disturbances, that the application of the controller The virtual inertia based on Mu-synthesis improves the stability of islanded microgrid clusters and damping of power fluctuations, and also reduces frequency deviations to a significant extent.
Sattar Shojaeiyan, Dr. Taher Niknam, Dr. Mehdi Nafar,
Volume 12, Issue 4 (2-2024)
Abstract
Achieving optimal and safe energy management and planning, taking into account the reduction of electricity production, transmission and distribution costs, as well as the reduction of environmental pollutants, has become increasingly important in many power companies in developing countries. With the optimal use of renewable energy sources and the use of a secure platform, including blockchain technology, the aforementioned goals can be achieved. To solve optimization problem, after modeling the hybrid AC-DC microgrid and considering the high complexity of the proposed formulation, the grey wolf optimization algorithm is proposed to solve the problem. In order to check the efficiency of the system under cyber-attacks, the system is subjected to false data injection attacks in different parts of the system, and then the operation is done under normal conditions and cyber-attacks. In this paper, MATLAB software package is used to solve the optimization problem and modeling the cyber-attacks. The operation results have been examined in different scenarios and the negative effects of such attacks are shown by comparing with the normal state. Then, to enhance the security of the system and prevent attacks, blockchain technology is presented to increase the security of the data exchanged in the system.
Dr, Ghazanfar Shahgholian,
Volume 13, Issue 1 (5-2024)
Abstract
Drop control is one of the conventional and widely used methods for microgrid control. Drop control is in the first level of hierarchical control, and it is used in microgrid to adjust voltage and frequency independently, and it does not need to be connected. This method offers high reliability, and is usually used in inverters that form microgrids. Microgrids can work in two modes connected to the network and island mode. In this article, an overview of the application of the drop control strategy in inverter-based island microgrids is presented according to the studies. Droop control is an example of decentralized control, and the importance of droop control in the islanded mode of operation will become apparent when it is possible to share energy among all units without the need to communicate with other units. In the drop control method, the frequency and voltage are adjusted according to the load demand and power balance in the network. This review study shows the importance of using drop control and its improvement in microgrids.
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