The Russian energy sector remains heavily reliant on thermal power plants,with gas generation accounting for approximately 66%of the installed capacity.However,the industry faces challenges such as depletion of reserv...The Russian energy sector remains heavily reliant on thermal power plants,with gas generation accounting for approximately 66%of the installed capacity.However,the industry faces challenges such as depletion of reserves,rising prices for hydrocarbons,and increasing concentrations of carbon dioxide in the atmosphere.This study focuses on developing new scientific and technical solutions to increase the efficiency and environmental safety of combined cycle power units.The research involves structural and parametric optimization of trinary cycle power plants operating on a methane-hydrogen mixture,as well as the development and optimization of turbine and heat exchange equipment for low-temperature power plants.The results show that the transition to trinary CCGT(Combine Cycle Gas Turbine)units with deep utilization and the use of hydrogen fuel can significantly reduce specific CO_(2) emissions and increase energy efficiency up to 0.21%with also increases in capacity of turbine of approximately 17 MW.The aim of this research is to calculate the efficiency,cost effectiveness and environmental-friendly solution for power generation using mixture of hydrogen-methane as fuel in combine cycle power plant that includes ORC.Additionally,the efficiency of the organic Rankine Cycle(ORC)benefits from the increased moisture,with capacity improvements of 1–2 MW observed when the hydrogen proportion rises from 25%to 50%.Moreover,the potential for zero emissions,coupled with significant increases in power output and efficiency,underscores hydrogen’s role as a pivotal component in the future of energy production.展开更多
The intermittency and volatility of wind and photovoltaic power generation exacerbate issues such as wind and solar curtailment,hindering the efficient utilization of renewable energy and the low-carbon development of...The intermittency and volatility of wind and photovoltaic power generation exacerbate issues such as wind and solar curtailment,hindering the efficient utilization of renewable energy and the low-carbon development of energy systems.To enhance the consumption capacity of green power,the green power system consumption optimization scheduling model(GPS-COSM)is proposed,which comprehensively integrates green power system,electric boiler,combined heat and power unit,thermal energy storage,and electrical energy storage.The optimization objectives are to minimize operating cost,minimize carbon emission,and maximize the consumption of wind and solar curtailment.The multi-objective particle swarm optimization algorithm is employed to solve the model,and a fuzzy membership function is introduced to evaluate the satisfaction level of the Pareto optimal solution set,thereby selecting the optimal compromise solution to achieve a dynamic balance among economic efficiency,environmental friendliness,and energy utilization efficiency.Three typical operating modes are designed for comparative analysis.The results demonstrate that the mode involving the coordinated operation of electric boiler,thermal energy storage,and electrical energy storage performs the best in terms of economic efficiency,environmental friendliness,and renewable energy utilization efficiency,achieving the wind and solar curtailment consumption rate of 99.58%.The application of electric boiler significantly enhances the direct accommodation capacity of the green power system.Thermal energy storage optimizes intertemporal regulation,while electrical energy storage strengthens the system’s dynamic regulation capability.The coordinated optimization of multiple devices significantly reduces reliance on fossil fuels.展开更多
To reduce carbon emissions,clean energy is being integrated into the power system.Wind power is connected to the grid in a distributed form,but its high variability poses a challenge to grid stability.This article com...To reduce carbon emissions,clean energy is being integrated into the power system.Wind power is connected to the grid in a distributed form,but its high variability poses a challenge to grid stability.This article combines wind turbine monitoring data with numerical weather prediction(NWP)data to create a suitable wind power prediction framework for distributed grids.First,high-precision NWP of the turbine range is achieved using weather research and forecasting models(WRF),and Kriging interpolation locates predicted meteorological data at the turbine site.Then,a preliminary predicted power series is obtained based on the fan’s wind speed-power conversion curve,and historical power is reconstructed using variational mode decomposition(VMD)filtering to form input variables in chronological order.Finally,input variables of a single turbine enter the temporal convolutional network(TCN)to complete initial feature extraction,and then integrate the outputs of all TCN layers using Long Short Term Memory Networks(LSTM)to obtain power prediction sequences for all turbine positions.The proposed method was tested on a wind farm connected to a distributed power grid,and the results showed it to be superior to existing typical methods.展开更多
In the long term,coal will remain a competitive resource in the thermal power sector,primarily due to its abundant global reserves and low costs.Despite numerous factors,including signifi cant environmental concerns,t...In the long term,coal will remain a competitive resource in the thermal power sector,primarily due to its abundant global reserves and low costs.Despite numerous factors,including signifi cant environmental concerns,the global share of coal power generation has remained at 40%over the past four decades.Effi cient and clean coal combustion is a high priority wherever coal is used as a fuel.An improved low-power boiler design has been proposed to enhance effi ciency during fi xedbed coal combustion.This design reduces harmful emissions into the atmosphere by optimizing parameters and operating modes.In this study,mathematical modeling of gas velocity and temperature distribution during fi xed-bed coal combustion was conducted for a conventional grate system and an improved grate-free system.Experimental methods were employed to develop descriptive airfl ow models in the fi xed coal layer,considering nozzle diameter and air supply pressure in the furnace chamber without a grate system.Comparative evaluations of fi xed-bed coal combustion rates were performed using an experimental laboratory setup with both grate and grate-free stove systems.展开更多
Modern electric traction networks(ETN)are equipped with automated systems for commercial accounting of power consumption(ASCAPC),which allows solving properly the problems of enhancing the energy efficiency of transpo...Modern electric traction networks(ETN)are equipped with automated systems for commercial accounting of power consumption(ASCAPC),which allows solving properly the problems of enhancing the energy efficiency of transportation processes.Energy efficiency of ETNs is defined as the amount of power losses in ETN components:overhead catenary systems and traction transformers.Due to the instability of traction loads and changes in their location in space,the electric traction network is different from the general network.It is necessary to develop an approach for loss analysis in traction networks and in transformers of traction substations.To solve this prob-lem,a balance-based technique for power loss calculation in traction networks based on ASCAPC data is proposed.First,the balance-based technique presented here breaks down the power consumption of the train by source.Then,calculates technical power losses in 25 and 225 kV traction networks as well as in traction transformers.Last,the technique is implemented in the form of an algorithm tested on real-life data and it is ready for practical use.展开更多
It has been thought that wall thinning on the secondary side piping in nu-clear power plants is mostly caused by Flow-Accelerated Corrosion (FAC). Recently, it has been seen that wall thinning on the secondary side pi...It has been thought that wall thinning on the secondary side piping in nu-clear power plants is mostly caused by Flow-Accelerated Corrosion (FAC). Recently, it has been seen that wall thinning on the secondary side piping carrying two-phase flow is caused by not only FAC but also Liquid Droplet Impingement Erosion (LDIE). Moreover, it turns out that LDIE in nuclear power plants does not result from a single degradation mechanism but also from the simultaneous happenings of LDIE and FAC. This paper presents a comparison of the mass loss rate of the tested materials between carbon steel (A106 B) and low alloy steel (A335 P22) resulting from degradation effect. An experimental facility was set up to develop a prediction model for clarifying multiple degradation mechanisms that occur together. The experimental facility allows examining liquid droplet impingement erosion in the same conditions as the secondary side piping in nuclear power plants by generating the magnetite on the surface of the test materials. The magnetite is formed by controlling the water chemistry and the temperature of fluid inside the facility. In the initial stage of the experiments, the mass loss rate of A106 B was greater than that of A335 P22. However, after a certain period of time, the mass loss rate of A335 P22 became greater than that of A106 B. It is presumed that the results are caused by the different yield strengths of the test materials and the different degrees of buffer action of the magnetite deposited on their surfaces. The layer of magnetite on the surface of A106 is thicker than that of A335 P22, due to the different amount of chrome content. In nuclear power plants, carbon steel piping having experienced wall thinning degradation is generally replaced with low-alloy steel piping. However, the materials of pipes carrying two-phase flow should be selected considering their susceptibility to LDIE.展开更多
In this paper, operation characteristic of condensate polishing system is studied during startup, based on generator blowdown limit, given limit ion concentration in condensate during condenser leakage. Further give c...In this paper, operation characteristic of condensate polishing system is studied during startup, based on generator blowdown limit, given limit ion concentration in condensate during condenser leakage. Further give conclusion about condensate polishing system configuration and operation requirement： full flow condensate polishing system （CPS） is necessary to the units cooled by sea water, and it is better that one or two series put in service during normal operation other than all of them in hot standby. While continuous condensate tube leakage is 256 L/h, the units cooled by fresh water will be shutdown immediately, for this level leakage, whichever condensate polishing system capacity is 50% （30%） or 100%, action level 2 will be preformed, so 50% （30%） is enough for fresh water cooled units.展开更多
A dust collector is an important equipment in a thermal power plant,and reasonable selection of a dust collector is important for environmental protection in the power plant. Huaneng Xining Power Plant is located at a...A dust collector is an important equipment in a thermal power plant,and reasonable selection of a dust collector is important for environmental protection in the power plant. Huaneng Xining Power Plant is located at an elevation of 2 360 m. Based on the characteristics of the high altitude area and their special requirements for dust collectors,the selection of dust collectors for the thermal power unit in the high altitude area was studied,and then two types of dust collectors( a rotary electrode electrostatic precipitator and electric-bag composite precipitator) for the thermal power unit were compared from the aspects of technological and economical feasibility. Finally,a proposal to select a suitable dust collector for the thermal power plant was put forward.展开更多
To manage the wall thinning of carbon steel piping in nuclear power plants, the utility of Korea has performed thickness inspection for some quantity of pipe components during every refueling outage and determined whe...To manage the wall thinning of carbon steel piping in nuclear power plants, the utility of Korea has performed thickness inspection for some quantity of pipe components during every refueling outage and determined whether repair or replacement after evaluating UT data. Generally used UT thickness data evaluation methods are Band, Blanket, and PTP (Point to Point) methods. Those may not desirable to identify wall thinning on local area caused by erosion. This is because the space between inspecting points of those methods are wide for covering full surface being inspected components. When the evaluation methods are applied to a certain pipe component, unnecessary re-inspection may also be generated even though wall thinning of components does not progress. In those cases, economical loss caused by repeated inspection and problems of maintaining the pipe integrity followed by decreasing the number of newly inspected components may be generated. EPRI (Electric Power Research Institute in USA) has suggested several statistical methods such as FRIEDMAN test method, ANOVA (Analysis of Variance) method, Monte Carlo method, and TPM (Total Point Method) to distinguish whether multiple inspecting components have been thinned or not. This paper presents the NAM (Near Area of Minimum) method developed by KEPCO-E & C for distinguishing whether multiple inspecting components have been thinned or not. In addition, this paper presents the analysis results for multiple inspecting ones over three times based on the NAM method compared with the other methods suggested by EPRI.展开更多
The calculation of square roots is a frequently used operation in control systems of power electronics for different applications:motor drives,power converters,etc.At the same time,the execution of this procedure sign...The calculation of square roots is a frequently used operation in control systems of power electronics for different applications:motor drives,power converters,etc.At the same time,the execution of this procedure significantly loads microcontrollers and uses its power,which can be utilized for performing other important tasks.Therefore,it restricts the size of code,which can be processed by the microcontroller and compels developers to limit the number of functions,or to decrease execution frequency of a program.Thus,the calculation of square roots is a bottle-neck in implementation of high-performance control systems,thus effective optimization of this task is extremely important in modern and efficient devices.In respect that many applications do not need precise calculation of square roots,the optimization of execution time can be achieved by decreasing of precision of the result.The proposed technique is based on the approximation of parabola with hyperbola,which allows you to rapidly find the approximate value of a square root.Taking into account that many digital signal processors(DSP)are not equipped with an effective divider,the developed algorithm does not use divisions,so it can be executed faster.The payback for this optimization is approximation error with a maximum of 0.5%,however,it is acceptable for the overwhelming majority of control systems.展开更多
The paper considers some issues related to the evaluation of power plants using renewable energy sources： energy efficiency, economic efficiency, the share of renewable energy in the world＇s electricity generation. ...The paper considers some issues related to the evaluation of power plants using renewable energy sources： energy efficiency, economic efficiency, the share of renewable energy in the world＇s electricity generation. At one time in the world there was a myth that more energy is expended on the construction of wind and photoelectric power stations, than they produce for the service life. Adherents of this myth are still found in Russia. In response to this myth, numerous studies have been carried out for the manufacturers of wind turbines and photovoltaic modules. It was proved that these power plants spent energy on them are produced within a period of less than a year and the energy consumed by them cannot be taken into account, since it is renewable. The author showed that power plants on organic fuel and existing nuclear plants using depleted fuel with a coefficient less than unity fundamentally cannot compensate for the energy used during their construction. In the world, the concept of the LEC （Levelized Energy Cost） produced by any power plant is widely used to estimate economic efficiency. However, the formula for determining it, in the author＇s opinion, contains an inaccuracy, which is proposed to be eliminated. At present, there are different opinions on the role of RES （Renewable Energy Sources） in the production of electricity. A summary indicator is the share of renewable energy in the world＇s electricity generation. The determination of the actual share of RES and the forecast of its growth is of significant importance for the development of the world economy. The author shows the differences in the estimates and suggests an approach for establishing agreed estimates.展开更多
This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable cond...This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable conductor temperature as well as load current determination principles are proposed. On one hand, the principles are based on mechanical limitations; on the other hand, they are based on thermal limitations. The simulation tasks were based on specific data information of three existing overhead lines of Latvian power system as well as the planned 330 kV overhead line. Moreover, the special thermovision device was used for precious determination of conductor temperature of the existing transmission lines. The simulation results of the obtained data are reviewed in the paper.展开更多
Single-phase 25 kV traction networks of electrified alternating current(AC)railways create electromagnetic fields(EMFs)with significant levels of intensity.The most intense magnetic fields occur when short circuits ex...Single-phase 25 kV traction networks of electrified alternating current(AC)railways create electromagnetic fields(EMFs)with significant levels of intensity.The most intense magnetic fields occur when short circuits exist between the contact wire and rails or ground.Despite the short duration of exposure,they can adversely affect electronic devices and induce significant voltages in adjacent power lines,which is dangerous for operating personnel.Although numerous investigations have focused on modeling the EMF of traction networks and power lines,the challenge of determining the three-dimensional electromagnetic fields near metal supports during the flow of a short-circuit current through them is yet to be resolved.In this case,the field has a complex spatial structure that significantly complicates the calculations of intensities.This study proposes a methodology,algorithms,software,and digital models for determining the EMF in the described emergency scenarios.During the modeling process,the objects being studied were represented by segments of thin wires to analyze the distribution of the electric charge and calculate the intensities of the electric and magnetic fields.This approach was implemented in the Fazonord software,and the modeling results show a substantial increase in EMF levels close to the support,with a noticeable decrease in the levels as the distance from it increases.The procedure implemented in the commercial software Fazonord is universal and can be used to determine electromagnetic fields at any electrical power facility that includes live parts of limited length.Based on the proposed procedure,the EMF near the supports of overhead power lines and traction networks of various designs could be determined,the EMF levels at substations can be calculated,and the influence of metal structures located near traction networks,such as pedestrian crossings at railway stations,can be considered.展开更多
Global energy and environmental issues are becoming increasingly problematic,and the vibration and noise problem of 110 kV transformers,which are the most widely distributed,have attracted widespread attention from bo...Global energy and environmental issues are becoming increasingly problematic,and the vibration and noise problem of 110 kV transformers,which are the most widely distributed,have attracted widespread attention from both inside and outside the industry.DC bias is one of the main contributing factors to vibration noise during the normal operation of transformers.To clarify the vibration and noise mechanism of a 110 kV transformer under a DC bias,a multi-field coupling model of a 110 kV transformer was established using the finite element method.The electromagnetic,vibration,and noise characteristics during the DC bias process were compared and quantified through field circuit coupling in parallel with the power frequency of AC,harmonic,and DC power sources.It was found that a DC bias can cause significant distortions in the magnetic flux density,force,and displacement distributions of the core and winding.The contributions of the DC bias effect to the core and winding are different at Kdc=0.85.At this point,the core approached saturation,and the increase in the core force and displacement slowed.However,the saturation of the core increased the leakage flux,and the stress and displacement of the winding increased faster.The sound field distribution characteristics of the 110 kV transformer under a DC bias are related to the force characteristics.When the DC bias coefficient was 1.25,the noise sound pressure level reached 73.6 dB.展开更多
This study explores the mechanism behind the generation of pressure pulses on the outer surface of a molten metal droplet when immersed in water.The absence of any external trigger is assumed,and the droplet is surrou...This study explores the mechanism behind the generation of pressure pulses on the outer surface of a molten metal droplet when immersed in water.The absence of any external trigger is assumed,and the droplet is surrounded by a vapor layer with surface hydrodynamic waves at the vapor-liquid interface.The study examines the heating conditions of a cylindrical column of water used to model a volume of cold liquid interacting with a hot metal surface,which explosively boils upon direct contact.Within the framework of classical homogeneous nucleation theory,the relationship between pressure pulse magnitude and rise time and the size of the contact area and surface temperature of the droplet is established.A criterion for determining the magnitude of the pressure pulse is derived,showing that significant pressure pulses occur within a narrow range of values for this criterion.Experimental investigations have been conducted to measure the key parameters—such as the duration and area of contact and pressure amplitude buildup—when room-temperature water comes into contact with a hot steel surface.The experimental results are compared with the theoretical predictions.Incorporating Skripov’s theory of explosive boiling into the model helps explain the relationship between the pressure pulse and contact area,only when the droplet surface temperature is near or exceeds the temperature of the maximum possible water superheating.展开更多
Structural collapse under blast loads is a very complex process. For several decades, the engineering profession has considered some approaches to analyze the essential physics of collapse phenomena. Recently, the int...Structural collapse under blast loads is a very complex process. For several decades, the engineering profession has considered some approaches to analyze the essential physics of collapse phenomena. Recently, the interest in this topic has risen to an apex since the collapse of the World Trade Center towers. A two-step analysis approach to capture the characteristics of structural collapse during explosions is proposed. A numerical example is presented to illustrate the performance of the presented approach.展开更多
Numerical simulation are conducted to explore the characteristics of the axial inflow and related aerodynamic noise for a large-scale adjustable fan with the installation angle changing from−12°to 12°.In suc...Numerical simulation are conducted to explore the characteristics of the axial inflow and related aerodynamic noise for a large-scale adjustable fan with the installation angle changing from−12°to 12°.In such a range the maximum static(gauge)pressure at the inlet changes from−2280 Pa to 382 Pa,and the minimum static pressure decreases from−3389 Pa to−8000 Pa.As for the axial intermediate flow surface,one low pressure zone is located at the junction of the suction surface and the hub,another is located at the suction surface close to the casing position.At the outlet boundary,the low pressure is negative and decreases from−1716 Pa to−4589 Pa.The sound pressure level of the inlet and outlet noise tends to increase monotonously by 11.6 dB and 7.3 dB,respectively.The acoustic energy of discrete noise is always higher than that of broadband noise regardless of whether the inlet or outlet flow surfaces are considered.The acoustic energy ratio of discrete noise at the inlet tends to increase from 0.78 to 0.93,while at the outlet it first decreases from 0.79 to 0.73 and then increases to 0.84.展开更多
As primary separators in pressurized water reactors (PWRs), cyclone separators separate most of the water from vapor-water two-phase mixture, which is important to the safety and economics of nuclear power plants. To ...As primary separators in pressurized water reactors (PWRs), cyclone separators separate most of the water from vapor-water two-phase mixture, which is important to the safety and economics of nuclear power plants. To improve the performance of cyclone separators, we tested new structures in this study, e.g. porosity and inclined angle of the separator wall. Under different structures, separation efficiency and pressure drop were studied theoretically and experimentally. Results show that each of the structural parameters has an effect on separator performance, but none of the trends is monotonically in experimental ranges. Besides separator structures, the comprehensive performance is also determined by flow patterns. From segregated to homogeneous flow, the separation ability decreases. The separation efficiency is about 5% higher at 20° inclined angle when the superficial velocities are 0.012 and 16 m·s-1 for the liquid and gas, respectively. The separation efficiency is only 91% without an impeller, while it is up to 100% at the same superficial velocities of air and water, 16 and 0.015 m·s-1 , respectively. Based on the study, it is promising to understand deeply the separation mechanism and further to provide data for designing large-scaled separators for advanced pressurized water reactors.展开更多
Mesoporous silica(mSiO_(2))has attracted great interest as anode for lithium-ion batteries.However,the low intrinsic conductivity is a major challenge for its commercialization.In this study,a low-cost sol–gel method...Mesoporous silica(mSiO_(2))has attracted great interest as anode for lithium-ion batteries.However,the low intrinsic conductivity is a major challenge for its commercialization.In this study,a low-cost sol–gel method is employed to synthesize mesoporous silica anchored on graphene nanosheets(rGO)for lithium storage.The results exhibit that the nanocomposite(mSiO_(2)@rGO)with high surface area(616.45 m^(2)·g^(–1))has chemical coupling bonds(Si–O–C)between SiO2 and rGO species,which would be favorable for lithium storage upon synergistic effects.Consequently,the mSiO_(2)@rGO exhibits a high specific capacity of 1119.6 mAh·g^(–1)at 0.1 A·g^(–1)with outstanding cycling stability(92.5%retention over 1400 cycles at 1.0 A·g^(–1)).展开更多
基金This study conducted by Moscow Power Engineering Institute was financially supported by the Ministry of Science and Higher Education of the Russian Federation(project No.FSWF-2023-0014,contract No.075-03-2023-383,2023/18/01).
文摘The Russian energy sector remains heavily reliant on thermal power plants,with gas generation accounting for approximately 66%of the installed capacity.However,the industry faces challenges such as depletion of reserves,rising prices for hydrocarbons,and increasing concentrations of carbon dioxide in the atmosphere.This study focuses on developing new scientific and technical solutions to increase the efficiency and environmental safety of combined cycle power units.The research involves structural and parametric optimization of trinary cycle power plants operating on a methane-hydrogen mixture,as well as the development and optimization of turbine and heat exchange equipment for low-temperature power plants.The results show that the transition to trinary CCGT(Combine Cycle Gas Turbine)units with deep utilization and the use of hydrogen fuel can significantly reduce specific CO_(2) emissions and increase energy efficiency up to 0.21%with also increases in capacity of turbine of approximately 17 MW.The aim of this research is to calculate the efficiency,cost effectiveness and environmental-friendly solution for power generation using mixture of hydrogen-methane as fuel in combine cycle power plant that includes ORC.Additionally,the efficiency of the organic Rankine Cycle(ORC)benefits from the increased moisture,with capacity improvements of 1–2 MW observed when the hydrogen proportion rises from 25%to 50%.Moreover,the potential for zero emissions,coupled with significant increases in power output and efficiency,underscores hydrogen’s role as a pivotal component in the future of energy production.
基金funded by the National Key Research and Development Program of China(2024YFE0106800)Natural Science Foundation of Shandong Province(ZR2021ME199).
文摘The intermittency and volatility of wind and photovoltaic power generation exacerbate issues such as wind and solar curtailment,hindering the efficient utilization of renewable energy and the low-carbon development of energy systems.To enhance the consumption capacity of green power,the green power system consumption optimization scheduling model(GPS-COSM)is proposed,which comprehensively integrates green power system,electric boiler,combined heat and power unit,thermal energy storage,and electrical energy storage.The optimization objectives are to minimize operating cost,minimize carbon emission,and maximize the consumption of wind and solar curtailment.The multi-objective particle swarm optimization algorithm is employed to solve the model,and a fuzzy membership function is introduced to evaluate the satisfaction level of the Pareto optimal solution set,thereby selecting the optimal compromise solution to achieve a dynamic balance among economic efficiency,environmental friendliness,and energy utilization efficiency.Three typical operating modes are designed for comparative analysis.The results demonstrate that the mode involving the coordinated operation of electric boiler,thermal energy storage,and electrical energy storage performs the best in terms of economic efficiency,environmental friendliness,and renewable energy utilization efficiency,achieving the wind and solar curtailment consumption rate of 99.58%.The application of electric boiler significantly enhances the direct accommodation capacity of the green power system.Thermal energy storage optimizes intertemporal regulation,while electrical energy storage strengthens the system’s dynamic regulation capability.The coordinated optimization of multiple devices significantly reduces reliance on fossil fuels.
基金funded by National Key Research and Development Program of China (2021YFB2601400)。
文摘To reduce carbon emissions,clean energy is being integrated into the power system.Wind power is connected to the grid in a distributed form,but its high variability poses a challenge to grid stability.This article combines wind turbine monitoring data with numerical weather prediction(NWP)data to create a suitable wind power prediction framework for distributed grids.First,high-precision NWP of the turbine range is achieved using weather research and forecasting models(WRF),and Kriging interpolation locates predicted meteorological data at the turbine site.Then,a preliminary predicted power series is obtained based on the fan’s wind speed-power conversion curve,and historical power is reconstructed using variational mode decomposition(VMD)filtering to form input variables in chronological order.Finally,input variables of a single turbine enter the temporal convolutional network(TCN)to complete initial feature extraction,and then integrate the outputs of all TCN layers using Long Short Term Memory Networks(LSTM)to obtain power prediction sequences for all turbine positions.The proposed method was tested on a wind farm connected to a distributed power grid,and the results showed it to be superior to existing typical methods.
基金The Committee of Science of the Ministry of Science and Higher Education of the Republic of Kazakhstan(No.AP19679995)have funded this research.
文摘In the long term,coal will remain a competitive resource in the thermal power sector,primarily due to its abundant global reserves and low costs.Despite numerous factors,including signifi cant environmental concerns,the global share of coal power generation has remained at 40%over the past four decades.Effi cient and clean coal combustion is a high priority wherever coal is used as a fuel.An improved low-power boiler design has been proposed to enhance effi ciency during fi xedbed coal combustion.This design reduces harmful emissions into the atmosphere by optimizing parameters and operating modes.In this study,mathematical modeling of gas velocity and temperature distribution during fi xed-bed coal combustion was conducted for a conventional grate system and an improved grate-free system.Experimental methods were employed to develop descriptive airfl ow models in the fi xed coal layer,considering nozzle diameter and air supply pressure in the furnace chamber without a grate system.Comparative evaluations of fi xed-bed coal combustion rates were performed using an experimental laboratory setup with both grate and grate-free stove systems.
基金the state assign-ment of Ministry of Science and Higher Education of the Russian Federation(theme No 123102000012-2“Compre-hensive study of aerodynamic characteristics of plasma systems of thermochemical fuel preparation”,agreement No 075-03-2023-028/1 of 05.10.2023).
文摘Modern electric traction networks(ETN)are equipped with automated systems for commercial accounting of power consumption(ASCAPC),which allows solving properly the problems of enhancing the energy efficiency of transportation processes.Energy efficiency of ETNs is defined as the amount of power losses in ETN components:overhead catenary systems and traction transformers.Due to the instability of traction loads and changes in their location in space,the electric traction network is different from the general network.It is necessary to develop an approach for loss analysis in traction networks and in transformers of traction substations.To solve this prob-lem,a balance-based technique for power loss calculation in traction networks based on ASCAPC data is proposed.First,the balance-based technique presented here breaks down the power consumption of the train by source.Then,calculates technical power losses in 25 and 225 kV traction networks as well as in traction transformers.Last,the technique is implemented in the form of an algorithm tested on real-life data and it is ready for practical use.
文摘It has been thought that wall thinning on the secondary side piping in nu-clear power plants is mostly caused by Flow-Accelerated Corrosion (FAC). Recently, it has been seen that wall thinning on the secondary side piping carrying two-phase flow is caused by not only FAC but also Liquid Droplet Impingement Erosion (LDIE). Moreover, it turns out that LDIE in nuclear power plants does not result from a single degradation mechanism but also from the simultaneous happenings of LDIE and FAC. This paper presents a comparison of the mass loss rate of the tested materials between carbon steel (A106 B) and low alloy steel (A335 P22) resulting from degradation effect. An experimental facility was set up to develop a prediction model for clarifying multiple degradation mechanisms that occur together. The experimental facility allows examining liquid droplet impingement erosion in the same conditions as the secondary side piping in nuclear power plants by generating the magnetite on the surface of the test materials. The magnetite is formed by controlling the water chemistry and the temperature of fluid inside the facility. In the initial stage of the experiments, the mass loss rate of A106 B was greater than that of A335 P22. However, after a certain period of time, the mass loss rate of A335 P22 became greater than that of A106 B. It is presumed that the results are caused by the different yield strengths of the test materials and the different degrees of buffer action of the magnetite deposited on their surfaces. The layer of magnetite on the surface of A106 is thicker than that of A335 P22, due to the different amount of chrome content. In nuclear power plants, carbon steel piping having experienced wall thinning degradation is generally replaced with low-alloy steel piping. However, the materials of pipes carrying two-phase flow should be selected considering their susceptibility to LDIE.
文摘In this paper, operation characteristic of condensate polishing system is studied during startup, based on generator blowdown limit, given limit ion concentration in condensate during condenser leakage. Further give conclusion about condensate polishing system configuration and operation requirement： full flow condensate polishing system （CPS） is necessary to the units cooled by sea water, and it is better that one or two series put in service during normal operation other than all of them in hot standby. While continuous condensate tube leakage is 256 L/h, the units cooled by fresh water will be shutdown immediately, for this level leakage, whichever condensate polishing system capacity is 50% （30%） or 100%, action level 2 will be preformed, so 50% （30%） is enough for fresh water cooled units.
文摘A dust collector is an important equipment in a thermal power plant,and reasonable selection of a dust collector is important for environmental protection in the power plant. Huaneng Xining Power Plant is located at an elevation of 2 360 m. Based on the characteristics of the high altitude area and their special requirements for dust collectors,the selection of dust collectors for the thermal power unit in the high altitude area was studied,and then two types of dust collectors( a rotary electrode electrostatic precipitator and electric-bag composite precipitator) for the thermal power unit were compared from the aspects of technological and economical feasibility. Finally,a proposal to select a suitable dust collector for the thermal power plant was put forward.
文摘To manage the wall thinning of carbon steel piping in nuclear power plants, the utility of Korea has performed thickness inspection for some quantity of pipe components during every refueling outage and determined whether repair or replacement after evaluating UT data. Generally used UT thickness data evaluation methods are Band, Blanket, and PTP (Point to Point) methods. Those may not desirable to identify wall thinning on local area caused by erosion. This is because the space between inspecting points of those methods are wide for covering full surface being inspected components. When the evaluation methods are applied to a certain pipe component, unnecessary re-inspection may also be generated even though wall thinning of components does not progress. In those cases, economical loss caused by repeated inspection and problems of maintaining the pipe integrity followed by decreasing the number of newly inspected components may be generated. EPRI (Electric Power Research Institute in USA) has suggested several statistical methods such as FRIEDMAN test method, ANOVA (Analysis of Variance) method, Monte Carlo method, and TPM (Total Point Method) to distinguish whether multiple inspecting components have been thinned or not. This paper presents the NAM (Near Area of Minimum) method developed by KEPCO-E & C for distinguishing whether multiple inspecting components have been thinned or not. In addition, this paper presents the analysis results for multiple inspecting ones over three times based on the NAM method compared with the other methods suggested by EPRI.
文摘The calculation of square roots is a frequently used operation in control systems of power electronics for different applications:motor drives,power converters,etc.At the same time,the execution of this procedure significantly loads microcontrollers and uses its power,which can be utilized for performing other important tasks.Therefore,it restricts the size of code,which can be processed by the microcontroller and compels developers to limit the number of functions,or to decrease execution frequency of a program.Thus,the calculation of square roots is a bottle-neck in implementation of high-performance control systems,thus effective optimization of this task is extremely important in modern and efficient devices.In respect that many applications do not need precise calculation of square roots,the optimization of execution time can be achieved by decreasing of precision of the result.The proposed technique is based on the approximation of parabola with hyperbola,which allows you to rapidly find the approximate value of a square root.Taking into account that many digital signal processors(DSP)are not equipped with an effective divider,the developed algorithm does not use divisions,so it can be executed faster.The payback for this optimization is approximation error with a maximum of 0.5%,however,it is acceptable for the overwhelming majority of control systems.
文摘The paper considers some issues related to the evaluation of power plants using renewable energy sources： energy efficiency, economic efficiency, the share of renewable energy in the world＇s electricity generation. At one time in the world there was a myth that more energy is expended on the construction of wind and photoelectric power stations, than they produce for the service life. Adherents of this myth are still found in Russia. In response to this myth, numerous studies have been carried out for the manufacturers of wind turbines and photovoltaic modules. It was proved that these power plants spent energy on them are produced within a period of less than a year and the energy consumed by them cannot be taken into account, since it is renewable. The author showed that power plants on organic fuel and existing nuclear plants using depleted fuel with a coefficient less than unity fundamentally cannot compensate for the energy used during their construction. In the world, the concept of the LEC （Levelized Energy Cost） produced by any power plant is widely used to estimate economic efficiency. However, the formula for determining it, in the author＇s opinion, contains an inaccuracy, which is proposed to be eliminated. At present, there are different opinions on the role of RES （Renewable Energy Sources） in the production of electricity. A summary indicator is the share of renewable energy in the world＇s electricity generation. The determination of the actual share of RES and the forecast of its growth is of significant importance for the development of the world economy. The author shows the differences in the estimates and suggests an approach for establishing agreed estimates.
文摘This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable conductor temperature as well as load current determination principles are proposed. On one hand, the principles are based on mechanical limitations; on the other hand, they are based on thermal limitations. The simulation tasks were based on specific data information of three existing overhead lines of Latvian power system as well as the planned 330 kV overhead line. Moreover, the special thermovision device was used for precious determination of conductor temperature of the existing transmission lines. The simulation results of the obtained data are reviewed in the paper.
文摘Single-phase 25 kV traction networks of electrified alternating current(AC)railways create electromagnetic fields(EMFs)with significant levels of intensity.The most intense magnetic fields occur when short circuits exist between the contact wire and rails or ground.Despite the short duration of exposure,they can adversely affect electronic devices and induce significant voltages in adjacent power lines,which is dangerous for operating personnel.Although numerous investigations have focused on modeling the EMF of traction networks and power lines,the challenge of determining the three-dimensional electromagnetic fields near metal supports during the flow of a short-circuit current through them is yet to be resolved.In this case,the field has a complex spatial structure that significantly complicates the calculations of intensities.This study proposes a methodology,algorithms,software,and digital models for determining the EMF in the described emergency scenarios.During the modeling process,the objects being studied were represented by segments of thin wires to analyze the distribution of the electric charge and calculate the intensities of the electric and magnetic fields.This approach was implemented in the Fazonord software,and the modeling results show a substantial increase in EMF levels close to the support,with a noticeable decrease in the levels as the distance from it increases.The procedure implemented in the commercial software Fazonord is universal and can be used to determine electromagnetic fields at any electrical power facility that includes live parts of limited length.Based on the proposed procedure,the EMF near the supports of overhead power lines and traction networks of various designs could be determined,the EMF levels at substations can be calculated,and the influence of metal structures located near traction networks,such as pedestrian crossings at railway stations,can be considered.
基金supported by the Key R&D Program of Shandong Province(2021CXGC010210).
文摘Global energy and environmental issues are becoming increasingly problematic,and the vibration and noise problem of 110 kV transformers,which are the most widely distributed,have attracted widespread attention from both inside and outside the industry.DC bias is one of the main contributing factors to vibration noise during the normal operation of transformers.To clarify the vibration and noise mechanism of a 110 kV transformer under a DC bias,a multi-field coupling model of a 110 kV transformer was established using the finite element method.The electromagnetic,vibration,and noise characteristics during the DC bias process were compared and quantified through field circuit coupling in parallel with the power frequency of AC,harmonic,and DC power sources.It was found that a DC bias can cause significant distortions in the magnetic flux density,force,and displacement distributions of the core and winding.The contributions of the DC bias effect to the core and winding are different at Kdc=0.85.At this point,the core approached saturation,and the increase in the core force and displacement slowed.However,the saturation of the core increased the leakage flux,and the stress and displacement of the winding increased faster.The sound field distribution characteristics of the 110 kV transformer under a DC bias are related to the force characteristics.When the DC bias coefficient was 1.25,the noise sound pressure level reached 73.6 dB.
基金supported by the Ministry of Science and Higher Education of the Russian Federation(State Assignment No.075-00270-24-00).
文摘This study explores the mechanism behind the generation of pressure pulses on the outer surface of a molten metal droplet when immersed in water.The absence of any external trigger is assumed,and the droplet is surrounded by a vapor layer with surface hydrodynamic waves at the vapor-liquid interface.The study examines the heating conditions of a cylindrical column of water used to model a volume of cold liquid interacting with a hot metal surface,which explosively boils upon direct contact.Within the framework of classical homogeneous nucleation theory,the relationship between pressure pulse magnitude and rise time and the size of the contact area and surface temperature of the droplet is established.A criterion for determining the magnitude of the pressure pulse is derived,showing that significant pressure pulses occur within a narrow range of values for this criterion.Experimental investigations have been conducted to measure the key parameters—such as the duration and area of contact and pressure amplitude buildup—when room-temperature water comes into contact with a hot steel surface.The experimental results are compared with the theoretical predictions.Incorporating Skripov’s theory of explosive boiling into the model helps explain the relationship between the pressure pulse and contact area,only when the droplet surface temperature is near or exceeds the temperature of the maximum possible water superheating.
基金the National Basic Research Program(973) of China (No. 2002CB412709)the National Natural Science Foundation of China (No. 50378054)
文摘Structural collapse under blast loads is a very complex process. For several decades, the engineering profession has considered some approaches to analyze the essential physics of collapse phenomena. Recently, the interest in this topic has risen to an apex since the collapse of the World Trade Center towers. A two-step analysis approach to capture the characteristics of structural collapse during explosions is proposed. A numerical example is presented to illustrate the performance of the presented approach.
基金supported by Key Research and Development Project of Shandong Province[2019GSF109084]Young Scholars Program of Shandong University[2018WLJH73].
文摘Numerical simulation are conducted to explore the characteristics of the axial inflow and related aerodynamic noise for a large-scale adjustable fan with the installation angle changing from−12°to 12°.In such a range the maximum static(gauge)pressure at the inlet changes from−2280 Pa to 382 Pa,and the minimum static pressure decreases from−3389 Pa to−8000 Pa.As for the axial intermediate flow surface,one low pressure zone is located at the junction of the suction surface and the hub,another is located at the suction surface close to the casing position.At the outlet boundary,the low pressure is negative and decreases from−1716 Pa to−4589 Pa.The sound pressure level of the inlet and outlet noise tends to increase monotonously by 11.6 dB and 7.3 dB,respectively.The acoustic energy of discrete noise is always higher than that of broadband noise regardless of whether the inlet or outlet flow surfaces are considered.The acoustic energy ratio of discrete noise at the inlet tends to increase from 0.78 to 0.93,while at the outlet it first decreases from 0.79 to 0.73 and then increases to 0.84.
基金Supported by National Natural Science Foundation of China (No. 51006068)Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China
文摘As primary separators in pressurized water reactors (PWRs), cyclone separators separate most of the water from vapor-water two-phase mixture, which is important to the safety and economics of nuclear power plants. To improve the performance of cyclone separators, we tested new structures in this study, e.g. porosity and inclined angle of the separator wall. Under different structures, separation efficiency and pressure drop were studied theoretically and experimentally. Results show that each of the structural parameters has an effect on separator performance, but none of the trends is monotonically in experimental ranges. Besides separator structures, the comprehensive performance is also determined by flow patterns. From segregated to homogeneous flow, the separation ability decreases. The separation efficiency is about 5% higher at 20° inclined angle when the superficial velocities are 0.012 and 16 m·s-1 for the liquid and gas, respectively. The separation efficiency is only 91% without an impeller, while it is up to 100% at the same superficial velocities of air and water, 16 and 0.015 m·s-1 , respectively. Based on the study, it is promising to understand deeply the separation mechanism and further to provide data for designing large-scaled separators for advanced pressurized water reactors.
基金This study was financially supported by the Postdoctoral Science Foundation of Jiangsu Province(No.2019K295)the Six Talent Peaks Project in Jiangsu Province(No.XNY-007,2018)+3 种基金the“333”Project in Jiangsu Province(No.BRA2019277)the Natural Science Foundation of Jiangsu Province(No.BK20170549)and the National Natural Science Foundation of China(Nos.21706103 and 22075109)Sherif A.El-Khodary would like to thank Jiangsu University for supporting the post-doctoral fellowship and funding the current project.
文摘Mesoporous silica(mSiO_(2))has attracted great interest as anode for lithium-ion batteries.However,the low intrinsic conductivity is a major challenge for its commercialization.In this study,a low-cost sol–gel method is employed to synthesize mesoporous silica anchored on graphene nanosheets(rGO)for lithium storage.The results exhibit that the nanocomposite(mSiO_(2)@rGO)with high surface area(616.45 m^(2)·g^(–1))has chemical coupling bonds(Si–O–C)between SiO2 and rGO species,which would be favorable for lithium storage upon synergistic effects.Consequently,the mSiO_(2)@rGO exhibits a high specific capacity of 1119.6 mAh·g^(–1)at 0.1 A·g^(–1)with outstanding cycling stability(92.5%retention over 1400 cycles at 1.0 A·g^(–1)).
