Research Article
Renewable Energy Resources and Technologies
Babak Keyvani; Bahador Fani; Hamed Karimi; Majid Moazzami; Ghazanfar Shahgholian
Abstract
Conventional droop control method has been widely adopted for power sharing between Distributed Generators (DGs) in microgrids. However, the mismatched feeder impedance of the Voltage-Sourced Inverters (VSI) may generate reactive power sharing error during islanding operation of a microgrid. In this ...
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Conventional droop control method has been widely adopted for power sharing between Distributed Generators (DGs) in microgrids. However, the mismatched feeder impedance of the Voltage-Sourced Inverters (VSI) may generate reactive power sharing error during islanding operation of a microgrid. In this paper, an improved droop control method is suggested to improve the reactive power sharing accuracy. In the proposed method, the slope correction of the droop characteristics is performed in such a way that the reactive power sharing error is reduced. In this method, the errors of reactive power sharing are detected by applying a clear signal to the microgrids and, then, by adding a new term to the P-ω and correcting the slope of Q-E, the reactive power sharing is done. In this way, the proposed method can successfully improve the reactive power sharing accuracy even at different X/R ratios. Another feature of this method is its high operation speed compared to the other methods of droop feature correction. The simulation results for a prototype microgrid point to the efficiency and flexibility of the proposed method.
Research Article
Renewable Energy Resources and Technologies
Rahul Dogra; Sanjay Kumar; Nikita Gupta
Abstract
The use of these conventional resources causes continuous depletion of fossil fuels and increased greenhouse effect. Solar power is the major renewable resource used for power generation across the globe. Solar energy activities depend on the available potential of any geographical location. Therefore, ...
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The use of these conventional resources causes continuous depletion of fossil fuels and increased greenhouse effect. Solar power is the major renewable resource used for power generation across the globe. Solar energy activities depend on the available potential of any geographical location. Therefore, prior to the installation of solar technologies for these activities, estimation of solar potential is very important due to costly technologies. Data of solar potential is not present at every location in Himachal Pradesh (H. P.) due to the high cost of measurement instruments. The objective of this study includes the solar potential estimation for 12 cities of the H. P. The present study could be divided into two parts. Initially, Artificial Neural Networks (ANNs) are utilized to estimate global sun radiation utilizing meteorological and geographical data from 23 places. The ANN model with seven input parameters including latitude, longitude, altitude, air temperature, humidity, pressure, and wind speed were used to estimate the solar irradiation. Statistical indicators including Mean Absolute Percentage Error (MAPE) were used for the performance evaluation of these ANNs. The minimum MAPE value was obtained to be 2.39 % with Multi-Layer Perception (MLP) architecture 7-11-1. For the 12 districts of the H. P., the acquired network 7-11-1 was utilized to estimate Global Solar Radiation (GSR). The output of ANN model was implemented in Geographic Information System (GIS) environment to obtain the solar potential map for each month. The available map of the present study may be helpful for solar application in each district.
Research Article
Environmental Impacts and Sustainability
Davar Rezakhani; Abdol Hamid Jafari; Mohammad Ali Hajabassi
Abstract
The application of nanomaterials to concrete is an innovative approach to enhance mechanical properties and durability performances. In this work, the addition of a combination of Graphene Oxide Nano-Platelets (GONP) and Ground Granulated Blast Furnace Slag (GGBFS) was studied as admixture in concrete. ...
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The application of nanomaterials to concrete is an innovative approach to enhance mechanical properties and durability performances. In this work, the addition of a combination of Graphene Oxide Nano-Platelets (GONP) and Ground Granulated Blast Furnace Slag (GGBFS) was studied as admixture in concrete. Tests on mechanical and chloride permeation properties were conducted. The results showed that the mix with 0.05 % GONP and the mix with 30 % GGBFS obtained better mechanical strength than the rest of the mixes. The highest electrical resistivity was achieved for the 90-day cured sample with 50 % GGBFS in CONP-free concrete and the 0.01 % GONP in GGBFS-free concrete, which was found to be the most effective in increasing concrete resistance to chloride permeation. The mix with 0.1 w % GONP and 50 w % GGBFS exhibited considerable performance even with other mechanical and durability performances. The addition of 0.1 % graphene oxide and 50 % granular slag increased the compressive strength of the concrete sample by 19.9 % during 28 days and 17.6 % during 90 days compared to the conventional concrete sample. Concrete with a combination of 0.1 % graphene oxide and 50 % granular slag experienced an increase in flexural strength by 15 % during 28 days and 13.6 % during 90 days. A significant reduction in electrical conductivity from 4012C to 1200C was observed for 90-day cured samples containing 0.1 wt % GO and 50 wt % GGBFS compared to the conventional sample. Response Surface Method (RSM) applied to the test data presented an optimized concrete mix containing 0.08 w % GONP and 50 w % GGBFS, the outcome of which was in close agreement with the experimental results.
Research Article
Advanced Energy Technologies
Shokoofeh Bagheri; Hassan Moradi CheshmehBeigi
Abstract
Today, the presence of energy storage systems along with the alternative nature of renewable energy sources has become undeniable and one of these types of systems is battery energy storage systems. The most important factor in studying the stability of DC microgrids (DCMGs) is the stabilization of the ...
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Today, the presence of energy storage systems along with the alternative nature of renewable energy sources has become undeniable and one of these types of systems is battery energy storage systems. The most important factor in studying the stability of DC microgrids (DCMGs) is the stabilization of the DC bus voltage when an error occurs on its reference value. Therefore, batteries along with power electronic converters play an important role in maintaining DCMG stability. In this paper, the use of Cascaded Buck-Boost Converter (CBBC) can be considered as a suitable alternative to bidirectional buck-boost converter due to such advantages as high power density, 98 % efficiency, and higher operating temperature in battery. The control strategy is applied in the microgrid implemented in the converter system set with storage, and Virtual DC Machine (VDCM) is based on charging and discharging battery through CBBC. In the studied control method, the theoretical properties of the DC machine, which is responsible for amplifying the virtual inertia in the system, are directed to the CBBC for correct switching. VDCM can be changed from motoring to generating mode or vice versa, regardless of mechanical machinery. Therefore, the proposed control system is simulated in an islanded DCMG in Matlab/Simulink and the stability of the studied system is analyzed according to the small-signal model of the proposed control and converter units. According to the simulation results and small-signal model analysis, the stability of the proposed idea under different scenarios is confirmed.
Research Article
Advanced Energy Technologies
Ashkan Zolriasatein; Zahra RajabiMashhadi; Majid Rezaei Abadchi; Nastaran Riahi Noori; Siamak Abyazi
Abstract
The crisis of contamination that leads to the accumulation of dust particles on insulation equipment and electrical insulators has disrupted the electricity grid. Electric discharge on infected insulators in wet conditions is a serious threat to the reliability of the grid, which can lead to grid failure ...
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The crisis of contamination that leads to the accumulation of dust particles on insulation equipment and electrical insulators has disrupted the electricity grid. Electric discharge on infected insulators in wet conditions is a serious threat to the reliability of the grid, which can lead to grid failure and blackout. In this regard, the importance of hydrophobic and dustproof coatings in the electricity industry has increased in recent years. In this paper, silica nanoparticles in the silicon rubber matrix were used to coat ceramic insulators to decrease the environmental impact of dust and moisture on the insulator’s coatings. One of the essential properties of these coatings is their hydrophobicity to prevent possible problems in power transmission. With this regard, nanocomposites were applied to 70 kN insulators and the tests were designed according to the available standards. The performance of these nanocoatings was evaluated by the implementation of electrical, salt fog, and hydrophobicity tests. Finally, the nanocomposite sample containing 3 wt % silica was recognized as the best one.
