Original Article
Transformation of Generated Electricity by Renewable Energies to Grid
Ling Tan; Bin Wang; Julong Chen; Yongqing Zhu; Junqiu Fan; Jiang Hu
Abstract
Medium- and long-term PV power forecasting is of great significance for the planning and management of new energy grids, and the existing medium- and long-term PV power forecasting methods generally suffer from the problems of insufficient processing means and low forecasting efficiency. Aiming at the ...
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Medium- and long-term PV power forecasting is of great significance for the planning and management of new energy grids, and the existing medium- and long-term PV power forecasting methods generally suffer from the problems of insufficient processing means and low forecasting efficiency. Aiming at the challenges of weak spatial and temporal correlation of medium- and long-term PV power data, as well as data redundancy and low forecasting efficiency brought about by long-time forecasting, this paper proposes a medium- and long-term PV power forecasting method based on the Transformer, SP-Transformer (Spatiotemporal-ProbSparse Transformer), which aims to effectively capture the spatio-temporal correlation between meteorological and geographical elements and PV power. The method embeds the geographic location information of PV sites into the model through spatio-temporal location coding and designs a spatio-temporal probabilistic sparse self-attention mechanism, which reduces model complexity while allowing the model to better capture the spatio-temporal correlation between input data. To further enhance the model's ability to capture and generalize potential patterns in complex PV power data, this paper proposes a feature pyramid-based self-attention distillation module to ensure the accuracy and robustness of the model in long-term forecasting tasks. The SP-Transformer model performs well in the PV power forecasting task, with a medium-term (48 hours) forecasting accuracy of 93.8% and a long-term (336 hours) forecasting accuracy of 90.4%, both of which are better than all the comparative algorithms involved in the experiment.
Original Article
Electricity Generation by Green Energy Sources
Magdi G. Muftah; Mohamed Salem; Mahmood Swadi; Khlid Ben Hamad; Mohamad Kamarol
Abstract
This paper proposes a new modified P–Q control scheme with a simple design using Static Quadratic Optimization (SQO) concept for a grid-connected hybrid system of photovoltaic (PV) and Fuel Cell (FC) sources. Contrary to traditional design practices involving voltage-oriented control (VOC) employing ...
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This paper proposes a new modified P–Q control scheme with a simple design using Static Quadratic Optimization (SQO) concept for a grid-connected hybrid system of photovoltaic (PV) and Fuel Cell (FC) sources. Contrary to traditional design practices involving voltage-oriented control (VOC) employing proportional-integral (PI) controllers or existing predictive strategies involving quadratic optimization by iterative computation, this proposed design of SQO directly computes an analytical expression of dq-axis current references as the optimal solution of a static-quadratic cost minimization problem. The proposed design enables optimal real and reactive power control simultaneously in a single step. The design of an efficient voltage-oriented current controller effectively utilizes measured values of grid current and voltage, as well as reference powers, which allows optimal bidirectional reactive controlled supply or absorption of reactive powers according to grid needs. The simulation of the grid-connected system has been performed in a MATLAB/Simulink environment. The simulation outcome verified the proposed P-Q voltage-oriented current controller design with a power factor of 0.998, phase displacement of 0.12°, total harmonic distortion (THD) levels of 1.2% for current and 0.39% for voltage, strictly within the IEEE-519 standards.
Original Article
Wind Energy
E.Yu. Rakhimov; N.R. Avezova; F.Z. Jamoldinov; Samad Emamgholizadeh; M. Ziaii
Abstract
This study analyzes wind speeds across various regions of the Republic of Uzbekistan to assess wind potential at 10 meters above ground level. Utilizing meteorological data from 77 ground-based stations collected between 2000 and 2022 at three-hour intervals, wind power densities were calculated to evaluate ...
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This study analyzes wind speeds across various regions of the Republic of Uzbekistan to assess wind potential at 10 meters above ground level. Utilizing meteorological data from 77 ground-based stations collected between 2000 and 2022 at three-hour intervals, wind power densities were calculated to evaluate wind potential, with average wind speeds determined monthly and annually. Data analysis from 13 regions identified locations with high wind energy potential, computing wind power densities and Weibull distribution parameters for wind speeds. Maps of average annual wind speed and power distribution, along with wind rose diagrams, illustrated predominant wind directions essential for optimal wind turbine placement. The highest average wind speeds were recorded in the Republic of Karakalpakstan, Navoi, Bukhara, Dehkanabad district (Kashkadarya), and Bekabad city (Tashkent region). Notable wind potential was found in Jaslyk district (Karakalpakstan) at 202.01 W/m², Navoi city (94.05 W/m²), and Dehkanabad district (85.33 W/m²). These results suggest that regions with high wind potential offer significant opportunities for efficient wind energy use. A comparison with previous studies on Uzbekistan's wind potential confirmed the accuracy and reliability of the data, indicating a high degree of consistency. This information can guide optimal planning and strategic placement of wind energy installations, furthering the development of “green energy” and enhancing Uzbekistan’s energy security
Original Article
Energy Policy
Saravanakumar V; Balu P; Saravanan C; Navaneetha Krishnan P
Abstract
Renewable and cleaner diesel engine fuel has received a lot of attention recently as a result of the depletion of fossil resources. In light of this, biodiesel has proven to be a viable substitute for diesel fuel. The finest B20 Jamun blends were combined with three different types of nano-additives ...
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Renewable and cleaner diesel engine fuel has received a lot of attention recently as a result of the depletion of fossil resources. In light of this, biodiesel has proven to be a viable substitute for diesel fuel. The finest B20 Jamun blends were combined with three different types of nano-additives to create Syzygium cumini (Jamun) biodiesel, which was tested in a naturally aspirated diesel engine. Global researchers are increasingly developing novel nano-additives, recognizing them as a promising and effective approach for enhancing fuel properties and engine performance. This technology was combined with different biodiesels. Also included in this chapter is an examination of a test engine using three distinct nano-additives: titanium dioxide (TiO2), zirconium oxide (ZrO2), and cerium oxide (CeO2). These additives were combined to create the best blends of Syzygium cumini (B20), and the results were evaluated based on factors such as performance, combustion, and output emissions. Additionally, a proposal is made to further improve the construction of a realistic and economically feasible nanoparticle addition for diesel and biodiesel fuel.
Original Article
Electricity Generation by Green Energy Sources
Kaveh Soleimani; Ataollah Gharechae; Mohammad Javad Ketabdari
Abstract
This research evaluates the feasibility of utilizing wave energy at Chabahar Port as an alternative power source. The first part of the study analyzed seasonal and annual wind and wave characteristics, as well as the directional distributions of winds and waves, utilizing long-term buoy measurements. ...
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This research evaluates the feasibility of utilizing wave energy at Chabahar Port as an alternative power source. The first part of the study analyzed seasonal and annual wind and wave characteristics, as well as the directional distributions of winds and waves, utilizing long-term buoy measurements. The extractable power output was determined based on the wave scatter diagram for Chabahar Port and the power matrix of various existing wave power devices. The average annual wave power at this location is 4.1 kW/m. However, wave power exhibited significant variation across the autumn, winter, spring, and summer seasons, averaging 1.46, 1.48, 4.4, and 6.94 kW/m, respectively. Among the thirteen wave power concepts evaluated, the Wave Dragon and the 1500 kW Pelamis demonstrated the best performance. The Wave Dragon is identified as the preferred wave power device for Chabahar Port, considering its power production capability, seabed compatibility, and adaptability to diverse meteorological conditions. Additionally, RETScreen Expert software was employed to conduct a cost and emissions analysis, indicating that the Wave Dragon and Pelamis can reduce greenhouse gas emissions by 719.7 and 351.6 tons of carbon dioxide, respectively. Consequently, the Wave Dragon offers the most economical power solution for Chabahar Port, with a greater reduction in greenhouse gas emissions.
Review Paper
Energy Policy
Abolfazl Dehghanmongabadi; Zahra Tahmasbnia
Abstract
In recent decades, rapid urbanization and increasing demands for energy created serious challenges in energy supply and environmental conservation. Based on this fact that 71% to 86 % greenhouse gas emissions are from energy consumption in urban areas, the importance of using renewable energy sources ...
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In recent decades, rapid urbanization and increasing demands for energy created serious challenges in energy supply and environmental conservation. Based on this fact that 71% to 86 % greenhouse gas emissions are from energy consumption in urban areas, the importance of using renewable energy sources becomes increasingly evident. In this regard, the main objective of this research is to identify social sustainability indicators and strategies for developing the use of renewable energy in cities based on identified indicators. This research attempts to respond to the raised questions by conducting a narrative review of existing studies based on the scoping review methodology. The findings of this study examine the challenges in using renewable energy resources and emphasize that to increase the use of renewable energy sources, special attention must be paid to various indicators that affect social sustainability in urban communities. The findings of this study demonstrate that social sustainability indicators play a key role in increasing the use of renewable energy in urban communities, and that attention to these indicators can contribute to the sustainable development of energy in cities. Consequently, recommendations to promote the use of renewable energy in urban communities with an emphasis on social sustainability indicators have been presented.
Original Article
Wind Energy
Ali Khaleghi; Hadi Bayat
Abstract
The noise generated by a blade is assumed as one of the most central acoustic generation sources in a turbine. The sound induced by the movement of turbulent fluid over the turbine blade and its interaction with the surrounding environment causes the presence of vortices of different sizes in the turbulent ...
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The noise generated by a blade is assumed as one of the most central acoustic generation sources in a turbine. The sound induced by the movement of turbulent fluid over the turbine blade and its interaction with the surrounding environment causes the presence of vortices of different sizes in the turbulent flow. These vortices are considered as the major sources of acoustic waves in a wide range of frequencies. In the present study, the acoustic field induced by turbine blades is simulated by the aid of numerical simulation. In this respect, the flow_field around the blades is solved by using the flow governing equations and then the acoustic solution of flow is modeled by using the Ffowcs Williams-Hawkings acoustic model. The main objectives of the present study include investigations of sound propagation at different distances of turbine axis, the extent of sound propagation along the blade direction, and the effect of the cavity implemented over the blade on acoustic results. The obtained results reveal that the sound pressure level generally decreases as the observer’s distance increases. Furthermore, based on the obtained results, one can infer that the reduction in the sound pressure level is triggered by the presence of larger vortices with higher energy close to the blade (a larger sound pressure level) and smaller vortices at a further distance from the blade (a lower sound pressure level). Numerical simulations indicate that adding a cavity to the turbine blade does not reduce noise but instead increases the acoustic generation level.
Original Article
Systems with Low Energy Consumption
Ali Fahim; Ahmad Nazari; mohammad Zamen; Amirreza Salamat Asrami
Abstract
A significant portion of energy consumption, particularly during the summer, is attributed to cooling demands in buildings. The most common methods for providing cooling are vapor compression and absorption refrigeration systems. However, in recent years, alternative methods based on adsorption have ...
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A significant portion of energy consumption, particularly during the summer, is attributed to cooling demands in buildings. The most common methods for providing cooling are vapor compression and absorption refrigeration systems. However, in recent years, alternative methods based on adsorption have been explored, and some systems have even reached the commercial market. In Iran, however, such systems have only been investigated at the laboratory level. The goal of this study experimental evaluation of a silica gel–water adsorption cooling system. The constructed system included an adsorbent bed filled with silica gel, a condenser, an evaporator, a heating unit, and a cooling water circulation system. A key feature of this design is the use of a chamber for both the adsorbent bed and the condenser which makes the system simpler. After construction, the system was tested and its performance data were collected. The cooling energy produced at the end of each cycle was measured based on the temperature change in the evaporator. According to the results, the cooling energy per cycle ranged between 1.3 and 1.8 kWh, with a maximum heating energy requirement of approximately 1.8 kWh. Based on various experimental runs, the coefficient of performance (COP) of the system was calculated to be in the range of 0.035 to 0.048. The use of an integrated chamber simplifies the system, but it results in reduced performance.
Original Article
Solar Thermal Engineering
Mahdi Rezaei Rad; Rouzbeh Shafaghat; Amirhossein Aghajani Afghan; Behrad Alizadeh Kharkeshi
Abstract
This experimental study introduces a solar humidifier-dehumidifier desalination model as a type of open-air-open water (OAOW) system; also, a new condenser with thermoelectric modules is applied in the dehumidifier unit. The experimental tests were done by considering climate conditions in the north ...
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This experimental study introduces a solar humidifier-dehumidifier desalination model as a type of open-air-open water (OAOW) system; also, a new condenser with thermoelectric modules is applied in the dehumidifier unit. The experimental tests were done by considering climate conditions in the north of Iran (Mazandaran province, Babol), and the effect of the inlet air's temperature and flow rate on the system's functional characteristics and condenser was investigated to improve the performance. Sensors measured the data related to the fluid temperature and humidity of the cycle at different points; other data was also gathered by psychrometric chart and EES software. The results section investigates water generation rate, GOR, coefficient of performance (COP), and condenser efficiency. The results showed that the highest water production is 420 g/hr, and the highest GOR is 0.19. Also, the water production rate and COP increase as the inlet air temperature rises. At temperatures lower than 75o Celsius, due to the air saturation, the maximum point of the water production and COP occurs at a flow rate of 0.022 kg/s. at high temperatures, increasing the flow rate raises water production, and on the other hand, the COP in the condenser is 0.8 at the highest point. According to the economic analysis done for the proposed model, the freshwater cost is 0.098-0.049 $/year for one liter.
Original Article
Photovoltaic Systems
Maede Khakpour; Yaser Karimi; Mohammad-Hadi Zare
Abstract
To address key challenges in the widespread adoption of electric vehicles, this article introduces a bidirectional, integrated on-board battery charger capable of flexibly drawing power from various AC sources, such as single-phase and three-phase grids, as well as renewable energy DC sources like photovoltaic ...
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To address key challenges in the widespread adoption of electric vehicles, this article introduces a bidirectional, integrated on-board battery charger capable of flexibly drawing power from various AC sources, such as single-phase and three-phase grids, as well as renewable energy DC sources like photovoltaic (PV) energy systems. The charger is designed for vehicles with an open-end winding motor powered by a dual inverter, consisting of two three-phase traction inverters and two sets of batteries. The proposed design utilizes a bidirectional current source converter at the input stage and integrates the dual inverter and the motor windings' leakage inductance as part of the charger, reducing both size and cost. Operating bidirectionally, the charger supports various grid support strategies, offering controlled active and reactive power with low total harmonic distortion (THD) in the grid current. It can also be directly connected to PV panels or DC fast-charging stations. A zero-net-torque-generating, interleaved switching pattern is employed to control the dual inverter switches, minimizing current ripple throughout the system. This article provides a detailed explanation and analysis of the proposed integrated charger, with system feasibility and performance validated through simulations.
Original Article
Energy Policy
Ali Eyvazi
Abstract
This evaluation presents a new multi-generation system that incorporates a gas turbine, an appropriate transformer, a cogeneration system, and a heat exchanger for generating electricity along with heating and cooling capabilities. A comprehensive analysis of the system's thermodynamic and economic performance ...
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This evaluation presents a new multi-generation system that incorporates a gas turbine, an appropriate transformer, a cogeneration system, and a heat exchanger for generating electricity along with heating and cooling capabilities. A comprehensive analysis of the system's thermodynamic and economic performance has been conducted. The waste heat from the gas turbine is captured and utilized to generate additional electricity within the turbine, while cooling capacity is achieved by recovering heat from the absorption transformer. Among the assessment techniques used, the application of cutting-edge technology enhances cost efficiency, resulting in improved economic effectiveness across various production systems. A sensitivity analysis was also performed to assess how the system responds to different conditions. Additionally, a two-objective genetic optimization algorithm was employed to identify the optimal solutions. The thermodynamic assessment indicates that the proposed system achieves an energy efficiency of 21.29% and an exergy efficiency of 20.68%. The analysis reveals that the system's cooling capacity is 2,746 kW, while the total exergy destruction within the system is 2,409 kW. The system is expected to produce a heating load of 2,921 kW and an output power of 3,874 kW. The economic analysis shows that with a total cost of 93.56 $/s and a combined investment and maintenance cost of 1,732 $/s, the proposed system is highly cost-effective.
Original Article
Energy Policy
Seyed Zaman Hosseini; Farhad Hossinzadeh Lotfi; Mahnaz Ahadzadeh Namin
Abstract
Assessment of progress and regression of organizations is necessary to determine their performance and determination of the efficacy of managerial decisions, supply usage, and weak and strong points for the senior managers and decision-makers. They can improve the efficiency of the units based on this ...
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Assessment of progress and regression of organizations is necessary to determine their performance and determination of the efficacy of managerial decisions, supply usage, and weak and strong points for the senior managers and decision-makers. They can improve the efficiency of the units based on this assessment. In this paper, using data envelopment analysis, the performance of regional electric companies of Iran in 2015 and 2016 is assessed. Because of semi-positive and negative indexes, the Slack-Based Measure (SBM) model of efficiency is developed for the 16 regional electric companies of Iran. To determine progress and regression in 2016 compared with 2015, models are proposed to compute the indexes of productivity. Finally, solving the proposed models, the Malmquist productivity index is computed for regional electric companies of Iran with 18 input, intermediate and output indexes and considering the amount of production of renewable energies as one of the important output indexes because of the irrefutable necessity of this kind of energies in the world. Their progress and regression are obtained using the Gams software showing progress in two companies, and regression in 13 companies while one company had neither progress nor regression. Studies performed show that agility of the organizational structure, financial and human resource limitations, sanctions and imbalance between the actual price of production of one kilowatt-hour of electricity and its sale price are most effective factors on the progress and regression of the companies.
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