The rapid growth of distributed generator(DG)capacities has introduced additional controllable assets to improve the performance of distribution systems in terms of service restoration.Renewable DGs are of particular ...The rapid growth of distributed generator(DG)capacities has introduced additional controllable assets to improve the performance of distribution systems in terms of service restoration.Renewable DGs are of particular interest to utility companies,but the stochastic nature of intermittent renewable DGs could have a negative impact on the electric grid if they are not properly handled.In this study,we investigate distribution system service restoration using DGs as the primary power source,and we develop an effective approach to handle the uncertainty of renewable DGs under extreme conditions.The distribution system service restoration problem can be described as a mixed-integer second-order cone programming model by modifying the radial topology constraints and power flow equations.The uncertainty of renewable DGs will be modeled using a chance-constrained approach.Furthermore,the forecast errors and noises in real-time operation are solved using a novel model-free control algorithm that can automatically track the trajectory of real-time DG output.The proposed service restoration strategy and model-free control algorithm are validated using an IEEE 123-bus test system.展开更多
This study describes an automatic berthing system with mooring lines. It is designed to be berthed by using mooring device on the upper deck of a ship. It is to berth once maintaining parallel with the quay by control...This study describes an automatic berthing system with mooring lines. It is designed to be berthed by using mooring device on the upper deck of a ship. It is to berth once maintaining parallel with the quay by controlling both forward and aft breast lines. Berthing method is used through length adjustment of mooring lines connected between ship and quay by controlling the angular velocity and the torque of hydraulic motor in mooring device. The study is conducted under three changing conditions of draft, such as even-keel, rise of the gravity center and trim to stern. Variables affecting berthing stability are determined based on the control performance of each condition. Bond graphs method is used to model the system. Controller is designed as PID control method of reference-model algorithm. The control program is composed of synchronous control system based on the equations derived with the numerical analysis. The tank test is conducted to verify the usefulness of the control program.展开更多
In this paper a new market based analytical model is proposed for optimal placement of Wind Turbines (WTs) in power systems. In addition to wind turbines, thermal units (THUs) and Pumped Storage Hydro Power Plants (PS...In this paper a new market based analytical model is proposed for optimal placement of Wind Turbines (WTs) in power systems. In addition to wind turbines, thermal units (THUs) and Pumped Storage Hydro Power Plants (PSHPPs) owners participate in power market. Objective function is defined as participants’ social welfare achieved from power pool and ancillary markets in yearly horizon. Wind turbines have been modeled by probability-generation tree scenarios based on statistical information. We concentrate on investment profits of WTs numbers and its generation capacity beside to PSHPPs and THUs power plants in power systems due to increase in high flexible tools for Independent system operator into the planning and operation planning time interval. For effectiveness evaluation of proposed model, simulation studies are applied on 14-Bus IEEE test power system.展开更多
A kind of micro/nanostructured 2205 duplex stainless steel(DSS)with uniform distribution of nanocrystals was prepared via aluminothermic reaction method.The analysis of stress-strain curve showed that the fracture str...A kind of micro/nanostructured 2205 duplex stainless steel(DSS)with uniform distribution of nanocrystals was prepared via aluminothermic reaction method.The analysis of stress-strain curve showed that the fracture strength and elongation of the specimen were 946 MPa and 24.7%,respectively.At present,the research on microstructure of bimodal 2205 DSS at room temperature(RT)mainly depended on scanning electron microscope(SEM)observation after loading experiments.The test result indicates that there are two different yield stages in stress-strain curve of specimen during tensile process.The microstructure of duplex bimodal structured stainless steel consists of two pairs of soft hard regions and phases.By studying deformation mechanism of bimodal structured stainless steel,the interaction between soft phase and hard phase are discussed.The principle of composition design and microstructure control of typical duplex stainless steel is obtained,which provides an important research basis for designing of advanced duplex stainless steel.展开更多
In this paper, a multi-objective load shedding framework on the power system is presented. The frame work is useable in any kind of smart power systems;the word of smart here refers to the availability of data transmi...In this paper, a multi-objective load shedding framework on the power system is presented. The frame work is useable in any kind of smart power systems;the word of smart here refers to the availability of data transmission infrastructure (like PLC or power line carrier) in the system, in order to carry the system data to the load shedding framework. This is an open framework that means it can optimize load shedding problem by considering unlimited number of objective functions, in other word, the number of objectives can be as much as the operator decides, finally in the end of frame work just one matrix breaker state is chosen in a way of having the most compatibility with the operator ideas which are determined by objectives importance percentage which are one input groups of the framework. A two-stage methodology is used for the optimal load shedding problem. In the first stage, Discrete Multi-objective Particle Swarm Optimization method is used to find a collection of the best states of load shedding (Pareto front). In the second stage, the fuzzy logic is used as a Pareto front inference engine. Fuzzy selection algorithm (FSA) is designed in a way that it can infer according to the operator’s opinion without the expert interference that means rule base is formed automatically by fuzzy algorithm. FSA is consisted of two parts. Membership functions and rules base are formed automatically in the first part, the former in accordance with the costs of Pareto front particles and the latter in correspondence with importance percentage of objectives which are entered to FSA by operator;in other word, decision matrix is formed automatically in the algorithm according to the cost of Pareto front particles and importance percentage of objectives. In the Second part, Mamdani inference engine scrutinizes the Pareto front particles by the use of formed membership functions and rules base to know if they are compatible to operator’s opinion or not. Getting this approach, cost functions of each particle are considered as the inputs of (FSA), then a fuzzy combined fitness (FCF) is allocated to each Pareto front particle by Mamdani inference engine. In other word, FCF shows how much the particle is compatible to the operator’s opinion. Finding minimum FCF, final inference is done. The proposed method is tested on 30-bus, and 118-bus IEEE systems by considering two or three objective functions and the results are presented.展开更多
The seismic hazard value is a fundamental quantity for the seismic risk assessment and for the determination of terms of references of seismic design of important facilities as dams, chemical plants, nuclear power pla...The seismic hazard value is a fundamental quantity for the seismic risk assessment and for the determination of terms of references of seismic design of important facilities as dams, chemical plants, nuclear power plants, etc.. In real sites, the seismic hazard value is influenced by both, the earthquake sizes, the impacts of which in a given site may be expected, and the properties of geological structure through which seismic waves spread from earthquake loci to a given site. The seismic risk is predetermined by hazard value, distribution of assets in the given site and asset numbers and vulnerabilities. The paper describes the used procedure of hazard assessment of important sites. The attention is especially paid to the basic steps as the data collection （homogeneity level, uncertainty and vagueness）, the focal region boundaries （their uncertainties and vagueness）, and the maximum expected earthquake size in each focal region that must be taken into account （its uncertainty and vagueness）, because they substantially influence the hazard value. Discussion is also concentrated to the attenuation that Central Europe substantially depends on the azimuth between earthquake focus and the given site. The attenuation differences are shown in seismic scenarios for individual focal regions. They are caused by focal mechanisms in near focal zone and differences in structure properties in distant zone; the boundary between near and distant zone in Central Europe is ca 2.5 h, where h is the focal depth in km. The real results are given for a real locality in Central Europe. It is shown than that great influence on hazard value is caused by great differences in azimuth attenuation curves. It is the reality that the Bohemian Massif is characterised with very low seismic attenuation in comparison with its vicinity. The following real results are presented： geological structure of near site vicinity, earthquake catalogue for Central Europe, focal regions in Central Europe, attenuation curves in Central Europe, typical earthquake isoseismals for individual focal regions, frequency graph, recurrence probability curve, etc.. The approaches used for nuclear facilities were recommended by the IAEA （International Atomic Energy Agency）.展开更多
The first part of this study is focused on the numerical modelling and experimental investigation of transonic flow through a 2D model of the male rotor-housing gap in a dry screw compressor.Numerical simulations of t...The first part of this study is focused on the numerical modelling and experimental investigation of transonic flow through a 2D model of the male rotor-housing gap in a dry screw compressor.Numerical simulations of the clearance flow are performed with the help of the in-house compressible Navier-Stokes solver.Experimental measurements based on the Schlieren method in Toepler configuration are carried out.The objective of the second part of the study is to derive the analytical solution of gas microflow development in a gap between two parallel plates.The microflow is assumed to be laminar,incompressible and the velocity slip boundary conditions are considered at the walls.The constant velocity profile is prescribed at the inlet.For the mathematical description of the problem,the Oseen equation is used.The analytical results are compared with the numerical ones obtained using the developed incompressible Navier-Stokes solver including the slip flow boundary conditions.展开更多
Wind power is crucial for achieving carbon neutrality,but its output can vary due to local wind conditions.The spatio-temporal behavior of wind power generation connected to the power grid can have a significant impac...Wind power is crucial for achieving carbon neutrality,but its output can vary due to local wind conditions.The spatio-temporal behavior of wind power generation connected to the power grid can have a significant impact on system operations.To assess this impact,the use of long-term reanalysis results of wind data based on a numerical weather prediction(NWP)model is considered valid.However,in Japan,the behavior of on-shore wind power generation is influenced by diverse topographical and meteorological features(TMFs)of the installation site,making it challenging to assess possible operational impacts based solely on power curve-based estimates using a popular conversion equation.In this study,a nonparametric machine learning-based post-processing model that learns the statistical relationship between the TMFs at the target location and the actual wind farm(WF)output was developed to represent the expected per-unit output at each location.Focusing on historical reconstruction results and using this post-processing model to reproduce the real-world WF output behavior created a set of expected wind power generation profiles.The dataset includes hourly long term(1958-2012)wind power generation profiles expected under the WF installation assumptions at various on-shore locations in Japan with a 5 km spatial resolution and is expected to contribute to an accurate understanding of the impact of spatio-temporal wind power behavior.The dataset is publicly accessible at https://doi.org/10.5281/zenodo.11496867(Fujimotoet al.,2024).展开更多
基金the National Renewable Energy Laboratory(NREL)operated by Alliance for Sustainable Energy,LLC,for the U.S.Department of Energy(DOE)under Contract No.DE-AC36-08GO28308the U.S.Department of Energy Office of Electricity AOP Distribution Grid Resilience Project.The views expressed in the article do not necessarily represent the views of the DOE or the U.S.Government.The U.S.Government retains and the publisher,by accepting the article for publication,acknowledges that the U.S.Government retains a nonexclusive,paid-up,irrevocable,worldwide license to publish or reproduce the published form of this work,or allow others to do so,for U.S.Government purposes.
文摘The rapid growth of distributed generator(DG)capacities has introduced additional controllable assets to improve the performance of distribution systems in terms of service restoration.Renewable DGs are of particular interest to utility companies,but the stochastic nature of intermittent renewable DGs could have a negative impact on the electric grid if they are not properly handled.In this study,we investigate distribution system service restoration using DGs as the primary power source,and we develop an effective approach to handle the uncertainty of renewable DGs under extreme conditions.The distribution system service restoration problem can be described as a mixed-integer second-order cone programming model by modifying the radial topology constraints and power flow equations.The uncertainty of renewable DGs will be modeled using a chance-constrained approach.Furthermore,the forecast errors and noises in real-time operation are solved using a novel model-free control algorithm that can automatically track the trajectory of real-time DG output.The proposed service restoration strategy and model-free control algorithm are validated using an IEEE 123-bus test system.
基金financially supported by the Post Innovation Program of the Fisheries Science Institute of Chonnam National University
文摘This study describes an automatic berthing system with mooring lines. It is designed to be berthed by using mooring device on the upper deck of a ship. It is to berth once maintaining parallel with the quay by controlling both forward and aft breast lines. Berthing method is used through length adjustment of mooring lines connected between ship and quay by controlling the angular velocity and the torque of hydraulic motor in mooring device. The study is conducted under three changing conditions of draft, such as even-keel, rise of the gravity center and trim to stern. Variables affecting berthing stability are determined based on the control performance of each condition. Bond graphs method is used to model the system. Controller is designed as PID control method of reference-model algorithm. The control program is composed of synchronous control system based on the equations derived with the numerical analysis. The tank test is conducted to verify the usefulness of the control program.
文摘In this paper a new market based analytical model is proposed for optimal placement of Wind Turbines (WTs) in power systems. In addition to wind turbines, thermal units (THUs) and Pumped Storage Hydro Power Plants (PSHPPs) owners participate in power market. Objective function is defined as participants’ social welfare achieved from power pool and ancillary markets in yearly horizon. Wind turbines have been modeled by probability-generation tree scenarios based on statistical information. We concentrate on investment profits of WTs numbers and its generation capacity beside to PSHPPs and THUs power plants in power systems due to increase in high flexible tools for Independent system operator into the planning and operation planning time interval. For effectiveness evaluation of proposed model, simulation studies are applied on 14-Bus IEEE test power system.
基金Funded by the National Natural Science Foundation of China(No.51911530119)the Department of Education of Gansu Province Innovation Fund(No.2021A-023)the Open Fund Project of Key Laboratory of Solar Power System Engineering Project(No.2022SPKL01)。
文摘A kind of micro/nanostructured 2205 duplex stainless steel(DSS)with uniform distribution of nanocrystals was prepared via aluminothermic reaction method.The analysis of stress-strain curve showed that the fracture strength and elongation of the specimen were 946 MPa and 24.7%,respectively.At present,the research on microstructure of bimodal 2205 DSS at room temperature(RT)mainly depended on scanning electron microscope(SEM)observation after loading experiments.The test result indicates that there are two different yield stages in stress-strain curve of specimen during tensile process.The microstructure of duplex bimodal structured stainless steel consists of two pairs of soft hard regions and phases.By studying deformation mechanism of bimodal structured stainless steel,the interaction between soft phase and hard phase are discussed.The principle of composition design and microstructure control of typical duplex stainless steel is obtained,which provides an important research basis for designing of advanced duplex stainless steel.
文摘In this paper, a multi-objective load shedding framework on the power system is presented. The frame work is useable in any kind of smart power systems;the word of smart here refers to the availability of data transmission infrastructure (like PLC or power line carrier) in the system, in order to carry the system data to the load shedding framework. This is an open framework that means it can optimize load shedding problem by considering unlimited number of objective functions, in other word, the number of objectives can be as much as the operator decides, finally in the end of frame work just one matrix breaker state is chosen in a way of having the most compatibility with the operator ideas which are determined by objectives importance percentage which are one input groups of the framework. A two-stage methodology is used for the optimal load shedding problem. In the first stage, Discrete Multi-objective Particle Swarm Optimization method is used to find a collection of the best states of load shedding (Pareto front). In the second stage, the fuzzy logic is used as a Pareto front inference engine. Fuzzy selection algorithm (FSA) is designed in a way that it can infer according to the operator’s opinion without the expert interference that means rule base is formed automatically by fuzzy algorithm. FSA is consisted of two parts. Membership functions and rules base are formed automatically in the first part, the former in accordance with the costs of Pareto front particles and the latter in correspondence with importance percentage of objectives which are entered to FSA by operator;in other word, decision matrix is formed automatically in the algorithm according to the cost of Pareto front particles and importance percentage of objectives. In the Second part, Mamdani inference engine scrutinizes the Pareto front particles by the use of formed membership functions and rules base to know if they are compatible to operator’s opinion or not. Getting this approach, cost functions of each particle are considered as the inputs of (FSA), then a fuzzy combined fitness (FCF) is allocated to each Pareto front particle by Mamdani inference engine. In other word, FCF shows how much the particle is compatible to the operator’s opinion. Finding minimum FCF, final inference is done. The proposed method is tested on 30-bus, and 118-bus IEEE systems by considering two or three objective functions and the results are presented.
文摘The seismic hazard value is a fundamental quantity for the seismic risk assessment and for the determination of terms of references of seismic design of important facilities as dams, chemical plants, nuclear power plants, etc.. In real sites, the seismic hazard value is influenced by both, the earthquake sizes, the impacts of which in a given site may be expected, and the properties of geological structure through which seismic waves spread from earthquake loci to a given site. The seismic risk is predetermined by hazard value, distribution of assets in the given site and asset numbers and vulnerabilities. The paper describes the used procedure of hazard assessment of important sites. The attention is especially paid to the basic steps as the data collection （homogeneity level, uncertainty and vagueness）, the focal region boundaries （their uncertainties and vagueness）, and the maximum expected earthquake size in each focal region that must be taken into account （its uncertainty and vagueness）, because they substantially influence the hazard value. Discussion is also concentrated to the attenuation that Central Europe substantially depends on the azimuth between earthquake focus and the given site. The attenuation differences are shown in seismic scenarios for individual focal regions. They are caused by focal mechanisms in near focal zone and differences in structure properties in distant zone; the boundary between near and distant zone in Central Europe is ca 2.5 h, where h is the focal depth in km. The real results are given for a real locality in Central Europe. It is shown than that great influence on hazard value is caused by great differences in azimuth attenuation curves. It is the reality that the Bohemian Massif is characterised with very low seismic attenuation in comparison with its vicinity. The following real results are presented： geological structure of near site vicinity, earthquake catalogue for Central Europe, focal regions in Central Europe, attenuation curves in Central Europe, typical earthquake isoseismals for individual focal regions, frequency graph, recurrence probability curve, etc.. The approaches used for nuclear facilities were recommended by the IAEA （International Atomic Energy Agency）.
基金supported by the grant GACR 101/08/0623 of the Czech Science Foundation and by the research project MSM4977751303 of the Ministry of Education,Youth and Sports of the Czech Republic
文摘The first part of this study is focused on the numerical modelling and experimental investigation of transonic flow through a 2D model of the male rotor-housing gap in a dry screw compressor.Numerical simulations of the clearance flow are performed with the help of the in-house compressible Navier-Stokes solver.Experimental measurements based on the Schlieren method in Toepler configuration are carried out.The objective of the second part of the study is to derive the analytical solution of gas microflow development in a gap between two parallel plates.The microflow is assumed to be laminar,incompressible and the velocity slip boundary conditions are considered at the walls.The constant velocity profile is prescribed at the inlet.For the mathematical description of the problem,the Oseen equation is used.The analytical results are compared with the numerical ones obtained using the developed incompressible Navier-Stokes solver including the slip flow boundary conditions.
文摘Wind power is crucial for achieving carbon neutrality,but its output can vary due to local wind conditions.The spatio-temporal behavior of wind power generation connected to the power grid can have a significant impact on system operations.To assess this impact,the use of long-term reanalysis results of wind data based on a numerical weather prediction(NWP)model is considered valid.However,in Japan,the behavior of on-shore wind power generation is influenced by diverse topographical and meteorological features(TMFs)of the installation site,making it challenging to assess possible operational impacts based solely on power curve-based estimates using a popular conversion equation.In this study,a nonparametric machine learning-based post-processing model that learns the statistical relationship between the TMFs at the target location and the actual wind farm(WF)output was developed to represent the expected per-unit output at each location.Focusing on historical reconstruction results and using this post-processing model to reproduce the real-world WF output behavior created a set of expected wind power generation profiles.The dataset includes hourly long term(1958-2012)wind power generation profiles expected under the WF installation assumptions at various on-shore locations in Japan with a 5 km spatial resolution and is expected to contribute to an accurate understanding of the impact of spatio-temporal wind power behavior.The dataset is publicly accessible at https://doi.org/10.5281/zenodo.11496867(Fujimotoet al.,2024).
