There is a growing need to explore the potential of coal-fired power plants(CFPPs)to enhance the utilization rate of wind power(wind)and photovoltaic power(PV)in the green energy field.This study developed a load regu...There is a growing need to explore the potential of coal-fired power plants(CFPPs)to enhance the utilization rate of wind power(wind)and photovoltaic power(PV)in the green energy field.This study developed a load regulation model for a multi-power generation system comprising wind,PV,and coal energy storage using realworld data.The power supply process was divided into eight fundamental load regulation scenarios,elucidating the influence of each scenario on load regulation.Within the framework of the multi-power generation system with the wind(50 MW)and PV(50 MW)alongside a CFPP(330 MW),a lithium-iron phosphate energy storage system(LIPBESS)was integrated to improve the system’s load regulation flexibility.The energy storage operation strategy was formulated based on the charging and discharging priority of the LIPBESS for each basic scenario and the charging and discharging load calculation method of LIPBESS auxiliary regulation.Through optimization using the particle swarm algorithm,the optimal capacity of LIPBESS was determined to be within the 5.24-4.88 MWh range.From an economic perspective,the LIPBESS operating with CFPP as the regulating power source was 49.1% lower in capacity compared to the renewable energy-based storage mode.展开更多
High-frequency oscillation(HFO)of gridconnected wind power generation systems(WPGS)is one of the most critical issues in recent years that threaten the safe access of WPGS to the grid.Ensuring the WPGS can damp HFO is...High-frequency oscillation(HFO)of gridconnected wind power generation systems(WPGS)is one of the most critical issues in recent years that threaten the safe access of WPGS to the grid.Ensuring the WPGS can damp HFO is becoming more and more vital for the development of wind power.The HFO phenomenon of wind turbines under different scenarios usually has different mechanisms.Hence,engineers need to acquire the working mechanisms of the different HFO damping technologies and select the appropriate one to ensure the effective implementation of oscillation damping in practical engineering.This paper introduces the general assumptions of WPGS when analyzing HFO,systematically summarizes the reasons for the occurrence of HFO in different scenarios,deeply analyses the key points and difficulties of HFO damping under different scenarios,and then compares the technical performances of various types of HFO suppression methods to provide adequate references for engineers in the application of technology.Finally,this paper discusses possible future research difficulties in the problem of HFO,as well as the possible future trends in the demand for HFO damping.展开更多
This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a u...This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a unified power quality conditioner(UPQC).In addition to supplying active power to the utility grid,the system of hybrid wind photovoltaic functions as a UPQC,compensating reactive power and suppressing the harmonic load currents.Additionally,the load is supplied with harmonic-free,balanced and regulated output voltages.Since PVWind-UPQC is established on a dual compensation scheme,the series inverter works like a sinusoidal current source,while the parallel inverter works like a sinusoidal voltage source.Consequently,a smooth alteration from interconnected operating modes to island operating modes and vice versa can be achieved without load voltage transients.Since PV-Wind-UPQC inverters handle the energy generated through the hybrid wind photovoltaic system and the energy demanded through the load,the converters should be sized cautiously.A detailed study of the flow of power via the PV-Wind-UPQC is imperative to gain a complete understanding of the system operation and the proper design of the converters.Thus,curves that allow the sizing of the power converters according to the power flow via the converters are presented and discussed.Simulation results are presented to assess both steady state and dynamic performances of the grid connected hybrid system of PV-Wind-UPQC.This investigation is verified by simulating and analyzing the results with Matlab/Simulink.展开更多
Electric-heat coupling characteristics of a cogeneration system and the operating mode of fixing electricity with heat are the main reasons for wind abandonment during the heating season in the Three North area.To imp...Electric-heat coupling characteristics of a cogeneration system and the operating mode of fixing electricity with heat are the main reasons for wind abandonment during the heating season in the Three North area.To improve the wind-power absorption capacity and operating economy of the system,the structure of the system is improved by adding a heat storage device and an electric boiler.First,aiming at the minimum operating cost of the system,the optimal scheduling model of the cogeneration system,including a heat storage device and electric boiler,is constructed.Second,according to the characteristics of the problem,a cultural gene algorithm program is compiled to simulate the calculation example.Finally,through the system improvement,the comparison between the conditions before and after and the simulation solutions of similar algorithms prove the effectiveness of the proposed scheme.The simulation results show that adding the heat storage device and electric boiler to the scheduling optimization process not only improves the wind power consumption capacity of the cogeneration system but also reduces the operating cost of the system by significantly reducing the coal consumption of the unit and improving the economy of the system operation.The cultural gene algorithm framework has both the global evolution process of the population and the local search for the characteristics of the problem,which has a better optimization effect on the solution.展开更多
Internal effects of the dynamic behaviors and nonlinear characteristics of a coupled fractional order hydropower generation system(HGS) are analyzed. A mathematical model of hydro-turbine governing system(HTGS) with r...Internal effects of the dynamic behaviors and nonlinear characteristics of a coupled fractional order hydropower generation system(HGS) are analyzed. A mathematical model of hydro-turbine governing system(HTGS) with rigid water hammer and hydro-turbine generator unit(HTGU) with fractional order damping forces are proposed. Based on Lagrange equations, a coupled fractional order HGS is established. Considering the dynamic transfer coefficient eis variational during the operation, introduced e as a periodic excitation into the HGS. The internal relationship of the dynamic behaviors between HTGS and HTGU is analyzed under different parameter values and fractional order. The results show obvious fast–slow dynamic behaviors in the HGS, causing corresponding vibration of the system, and some remarkable evolution phenomena take place with the changing of the periodic excitation parameter values.展开更多
Although transmission systems are able to cover most of the areas in many countries, there are still some isolated areas such as rural counties and remote desert lands where grid power cannot be accessed. Therefore, a...Although transmission systems are able to cover most of the areas in many countries, there are still some isolated areas such as rural counties and remote desert lands where grid power cannot be accessed. Therefore, a reliable and economical power supply scheme is required to solve the problem. One of them combines wind/solar power generation with the support of storage system. This paper is to give an overview of the optimization methodologies about the wind/solar stand-alone system supported by storage systems or integrating with other renewable or conventional power generation sources. It is shown that continued research and optimization methodology in this area are still in great need for performance improvement.展开更多
Making full use of wind power is one of the main purposes of the wind turbine generator control. Conventional hill climbing search (HCS) method can realize the maximum power point tracking (MPPT). However, the ste...Making full use of wind power is one of the main purposes of the wind turbine generator control. Conventional hill climbing search (HCS) method can realize the maximum power point tracking (MPPT). However, the step size of HCS method is constant so that it cannot consider both steady-state response and dynamic response. A fuzzy logical control (FLC) algorithm is proposed to solve this problem in this paper, which can track the maximum power point (MPP) quickly and smoothly. To evaluate MPPT algorithms, four performance indices are also proposed in this paper. They are the energy captured by wind turbine, the maximum power-point tracking time when wind speed changes slowly, the fluctuation magnitude of real power during steady state, and the energy captured by wind turbine when wind speed changes fast. Three cases are designed and simulated in MATLAB/Simulink respectively. The comparison of the three MPPT strategies concludes that the proposed fuzzy logical control algorithm is more superior to the conventional HCS algorithms.展开更多
Due to growing concerns regarding climate change and environmental protection,smart power generation has become essential for the economical and safe operation of both conventional thermal power plants and sustainable...Due to growing concerns regarding climate change and environmental protection,smart power generation has become essential for the economical and safe operation of both conventional thermal power plants and sustainable energy.Traditional first-principle model-based methods are becoming insufficient when faced with the ever-growing system scale and its various uncertainties.The burgeoning era of machine learning(ML)and data-driven control(DDC)techniques promises an improved alternative to these outdated methods.This paper reviews typical applications of ML and DDC at the level of monitoring,control,optimization,and fault detection of power generation systems,with a particular focus on uncovering how these methods can function in evaluating,counteracting,or withstanding the effects of the associated uncertainties.A holistic view is provided on the control techniques of smart power generation,from the regulation level to the planning level.The benefits of ML and DDC techniques are accordingly interpreted in terms of visibility,maneuverability,flexibility,profitability,and safety(abbreviated as the“5-TYs”),respectively.Finally,an outlook on future research and applications is presented.展开更多
In order to investigate the aerodynamic characteristics of 6-MW wind turbine, experimental study on the aerodynamic characteristics of the model rotor system and on characterization of a wind generation system is carr...In order to investigate the aerodynamic characteristics of 6-MW wind turbine, experimental study on the aerodynamic characteristics of the model rotor system and on characterization of a wind generation system is carried out. In the test, a thrust-matched rotor system and a geometry-matched rotor system, which utilize redesigned thrustmatched and original geometry-matched blades, respectively, are applied. The 6-MW wind turbine system is introduced briefly. The proper scaling laws for model tests are established in the paper, which are then implemented in the construction of a model wind turbine with optimally designed blades. And the parameters of the model are provided. The aerodynamic characteristics of the proposed 6-MW wind rotor system are explored by testing a 1:65.3 scale model at the State Key Laboratory of Ocean Engineering at Shanghai Jiao Tong University. Before carrying out the wind rotor system test, the turbulence intensity and spatial uniformity of the wind generation system are tested and results demonstrate that the characterization of the wind generation system is satisfied and the average turbulence intensity of less than 10% within the wind rotor plane is proved in the test. And then, the aerodynamic characteristics of 6-MW wind rotor system are investigated. The response characteristic differences between the thrust-matched rotor system and the geometry-matched rotor system are presented. Results indicate that the aerodynamic characteristics of 6-MW wind rotor with the thrust-matched rotor system are satisfied. The conclusion is that the thrust-matched rotor system can better reflect the characteristics of the prototype wind turbine. A set of model test method is proposed in the work and preparations for further model basin test of the 6-MW SPAR-type floating offshore wind turbine system are made.展开更多
Due to the intermittency and instability of Wind-Solar energy and easy compensation of hydropower, this study proposes a Wind-Solar-Hydro power optimal scheduling model. This model is aimed at maximizing the total sys...Due to the intermittency and instability of Wind-Solar energy and easy compensation of hydropower, this study proposes a Wind-Solar-Hydro power optimal scheduling model. This model is aimed at maximizing the total system power generation and the minimum ten-day joint output. To effectively optimize the multi-objective model, a new algorithm named non-dominated sorting culture differential evolution algorithm(NSCDE) is proposed. The feasibility of NSCDE was verified through several well-known benchmark problems. It was then applied to the Jinping Wind-Solar-Hydro complementary power generation system. The results demonstrate that NSCDE can provide decision makers a series of optimized scheduling schemes.展开更多
The use of high-temperature fuel cells as a power technology can improve the efficiency of electricity generation and achieve near-zero emissions of carbon dioxide.This work explores the performance of a 10 kW high-te...The use of high-temperature fuel cells as a power technology can improve the efficiency of electricity generation and achieve near-zero emissions of carbon dioxide.This work explores the performance of a 10 kW high-temperature molten carbonate fuel cell.The key materials of a single cell were characterized and analyzed using X-ray diffraction and scanning electron microscopy.The results show that the pore size of the key electrode material is 6.5 lm and the matrix material is a-LiAlO_(2).Experimentally,the open circuit voltage of the single cell was found to be 1.23 V.The current density was greater than 100 mA/cm^(2)at an operating voltage of 0.7 V.The 10 kW fuel cell stack comprised 80 single fuel cells with a total area of 2000 cm^(2)and achieved an open circuit voltage of greater than 85 V.The fuel cell stack power and current density could reach 11.7 kW and 104.5 mA/cm2 at an operating voltage of 56 V.The influence and long-term stable operation of the stack were also analyzed and discussed.The successful operation of a 10 kW high-temperature fuel cell promotes the large-scale use of fuel cells and provides a research basis for future investigations of fuel cell capacity enhancement and distributed generation in China.展开更多
The global Electricity Sector and its customers are faced with a number of challenges that are unparalleled since the advent of widespread electrification. Challenges including climate change, escalating energy prices...The global Electricity Sector and its customers are faced with a number of challenges that are unparalleled since the advent of widespread electrification. Challenges including climate change, escalating energy prices, energy security and energy efficiency are converging to drive fundamental change in the way energy is produced, delivered and utilized. The electricity system of the future must produce and distribute electricity that is reliable, affordable and clean. To accomplish these goals, both the electricity grid and the existing regulatory system must be smarter. This paper explores smart grid technologies, distributed generation systems, R & D efforts across Europe and the United States, and technical, economical and regulatory barriers facing modern utilities.展开更多
Disaster-hit and/or un-electrifed remote areas usually have electricity accessibility issues and an abundance of plant-derived debris and wood from destroyed wooden structures;this can be potentially addressed by empl...Disaster-hit and/or un-electrifed remote areas usually have electricity accessibility issues and an abundance of plant-derived debris and wood from destroyed wooden structures;this can be potentially addressed by employing a decentralized ultrasmall biomass-fed gasifcation power generating system.This paper presents an assessment of the technical viability of an ultra-small gasifcation system that utilizes densifed carbonized wood pellets/briquettes.The setup was run continuously for 100 h.A variety of biomass was densifed and carbonized by harnessing fugitive heat sources before charging into the reactor.Carbonized briquettes and furnished blends exhibited inferior gasifcation performance compared to the carbonized pellets.In the absence of tar blockage problems,steady-state conditions were achieved when pre-treated feedstock was used.Under steady-state conditions for carbonized pellets gasifcation operated at an equivalence ratio of 0.32,cold gas efciency and carbon conversion achieved 49.2%and 70.5%,respectively.Overall efciency and maximum power output of 20.3%and 21 kW were realised,respectively.It was found that the system could keep stable while the low heating valve of syngas was over 4 MJ/m^(3)on condition that avoiding tar blocking issues.The results indicate that the proposed compact ultra-small power generation system is a technically feasible approach to remedy power shortage challenge.In addition,process simulation considering carbonized wood gasifcation combined power generation was formulated to produce syngas and electricity.Woody pellets with the fow rate of 20 kg/h could generate a 15.18 kW power at the air fow rate of 40 Nm^(3)/h,which is in a good agreement with 15 kW in the 100 h operation.It is indicated that the gasifcation combined power generation cycle simulated by Aspen simulator could achieve reliable data to assist the complicated experiment operation.展开更多
Last decade witnessed tremendous research and development in the area of photo-electrolytic hydrogen generation using chemically stable nanostructured photo-cathode/anode materials. Due to intimately coupled charge se...Last decade witnessed tremendous research and development in the area of photo-electrolytic hydrogen generation using chemically stable nanostructured photo-cathode/anode materials. Due to intimately coupled charge separation and photo-catalytic processes, it is very difficult to optimize individual components of such system leading to a very low demonstrated solar-to-fuel efficiency (SFE) of less than 1%. Recently there has been growing interest in an integrated photovoltaic–electrochemical (PV–EC) system based on GaAs solar cells with the demonstrated SFE of 24.5% under concentrated illumination condition. But a high cost of GaAs based solar cells and recent price drop of poly-crystalline silicon (pc-Si) solar cells motivated researchers to explore silicon based integrated PV–EC system. In this paper a theoretical framework is introduced to model silicon-based integrated PV–EC device. The theoretical framework is used to analyze the coupling and kinetic losses of a silicon solar cell based integrated PV–EC water splitting system under varying temperature and illumination. The kinetic loss occurs in the range of 19.1%–27.9% and coupling loss takes place in the range of 5.45%–6.74% with respect to varying illumination in the range of 20–100?mW/cm2. Similarly, the effect of varying temperature has severe impact on the performance of the system, wherein the coupling loss occurs in the range of 0.84%–21.51% for the temperature variation from 25 to 50?°C. ? 2016 Science Press展开更多
Formal methods for test sequence generation from FSM have been studied widely andthoroughly,but most real communication systems can only be modeled as EFSM exactly.Data portion in EFSM brings difficulties for test sui...Formal methods for test sequence generation from FSM have been studied widely andthoroughly,but most real communication systems can only be modeled as EFSM exactly.Data portion in EFSM brings difficulties for test suite generation.In this paper,the strategyof generating test suite from protocols modelled as EFSM is presented.This strategy consid-ers testing of both the control portion and data portion of protocols.A software,the testsuite generation system(TSGS)based on above strategy,is introduced.展开更多
Paraphrase is an expression of a text with alternative words and orders to achieve a better clarity. Paraphrases have been found vital for augmenting training dataset, which aid to enhance performance of machine learn...Paraphrase is an expression of a text with alternative words and orders to achieve a better clarity. Paraphrases have been found vital for augmenting training dataset, which aid to enhance performance of machine learning models that intended for various natural language processing (NLP) tasks. Thus, recently, automatic paraphrase generation has received increasing attention. However, evaluating quality of generated paraphrases is technically challenging. In the literature, the importance of generated paraphrases is tended to be determined by their impact on the performance of other NLP tasks. This kind of evaluation is referred as extrinsic evaluation, which requires high computational resources to train and test the models. So far, very little attention has been paid to the role of intrinsic evaluation in which quality of generated paraphrase is judged against predefined ground truth (reference paraphrases). In fact, it is also very challenging to find ideal and complete reference paraphrases. Therefore, in this study, we propose semantic or meaning oriented automatic evaluation metric that helps to evaluate quality of generated paraphrases against the original text, which is an intrinsic evaluation approach. Further, we evaluate quality of the paraphrases by assessing their impact on other NLP tasks, which is an extrinsic evaluation method. The goal is to explore the relationship between intrinsic and extrinsic evaluation methods. To ensure the effectiveness of proposed evaluation methods, extensive experiments are done on different publicly available datasets. The experimental results demonstrate that our proposed intrinsic and extrinsic evaluation strategies are promising. The results further reveal that there is a significant correlation between intrinsic and extrinsic evaluation approaches.展开更多
Coal, petroleum and natural gas will still be the basis of economic development for a long time. However, with a rapider consumption speed, these fossil fuels will be exhausted in the near future. In addition, the usa...Coal, petroleum and natural gas will still be the basis of economic development for a long time. However, with a rapider consumption speed, these fossil fuels will be exhausted in the near future. In addition, the usage of these fossil fuels can also cause environmental pollution and greenhouse effect. To deal with energy security and environmental crisis, it is wise to work towards three directions: energy saving and emission reduction, energy recovery, exploration of new renewable energy. Currently, the electricity generation technology using piezoelectric material to recover the compressional or vibrational energy begins to draw attention. However, most of the researches are devoted to designing small self-powered devices. This paper presents an overview of the feasibility of piezoelectric power generation system for electric power system, in which the fundamentals of piezoelectric power generation and the feasible structure of the system are discussed.展开更多
In this study, a circular plate that is installing a piezoelectric element at its center is adopted as energy-harvesting system and is subjected to a harmonic point force. Because this system cannot avoid the influenc...In this study, a circular plate that is installing a piezoelectric element at its center is adopted as energy-harvesting system and is subjected to a harmonic point force. Because this system cannot avoid the influence of its acoustic radiation, the influence is considered theoretically using the equation of plate motion taking into account its radiation impedance and is estimated by the electricity generation efficiency, which is derived from the ratio of the electric power in the electricity generation and the mechanical power supplied to the plate. As a result, the efficiency is suppressed by the acoustic radiation from the plate, so that the efficiencies are so different in whether to take into consideration the radiation impedance or not. Because those results are verified by the electricity generation experiment and radiation acoustic energy has a hopeful prospect for improving the performance of this system, mechanical-acoustic coupling is used to make the most of the acoustic energy. Therefore, a cylinder that has the above plates at both ends is also adopted as the electricity generation system and mechanical-acoustic coupling is caused between the plate vibrations and an internal sound field into the cylindrical enclosure by subjecting one side of each plate to a harmonic point force. Then, the effect of coupling is evaluated by comparing with the efficiencies in the electricity generation system of only plate. Specifically, because the radiation impedance increases with the plate thickness, i.e., with the natural frequency of the plate, it is demonstrated that the effect of coupling becomes remarkable with increasing the thickness on the electricity generation efficiency.展开更多
A laboratory system was designed to generate bitumen fumes and expose tested samplers in a homogenised chamber. The system was also designed to condense the fumes in the form of oil that could be used as a standard fo...A laboratory system was designed to generate bitumen fumes and expose tested samplers in a homogenised chamber. The system was also designed to condense the fumes in the form of oil that could be used as a standard for further analytical method development. The laboratory system was evaluated in terms of stability, repeatability, aging, and ranges, focusing on the quality and quantity of the fumes and their physical characteristics. The fumes generated with the laboratory system were also compared to fumes emitted at workplaces to evaluate their similarity. The results demonstrated that laboratory fume generation was stable and repeatable. Humidity ranged from 20% to 80% RH and the total fume concentration ranged from 0.01 to 9.36 mg.m<sup>-3</sup>, covering the conditions encountered for road paving worksites. The fumes generated in the laboratory were found to be similar to those of workplaces, with slight differences in light compounds equivalent to C12 and below n-alkanes. Thus, the system designed in this study is considered capable of generating bitumen fumes used to develop sampling and analysis methods.展开更多
This research is based on the detailed design and study of a plant power generation system for green building roofs based on the combination of bionics and design science.The selection of power generation plants is ca...This research is based on the detailed design and study of a plant power generation system for green building roofs based on the combination of bionics and design science.The selection of power generation plants is carried out through experiments and research,and based on which the connection between the plant power generation unit and the internal circuit of the building is studied to generate a complete building roof plant power generation system.展开更多
基金supported by the Natural Science Foundation of China(Grant Nos.52076079,52206010)Natural Science Foundation of Hebei Province,China(Grant No.E2020502013)the Fundamental Research Funds for the Central Universities(2021MS076,2021MS079).
文摘There is a growing need to explore the potential of coal-fired power plants(CFPPs)to enhance the utilization rate of wind power(wind)and photovoltaic power(PV)in the green energy field.This study developed a load regulation model for a multi-power generation system comprising wind,PV,and coal energy storage using realworld data.The power supply process was divided into eight fundamental load regulation scenarios,elucidating the influence of each scenario on load regulation.Within the framework of the multi-power generation system with the wind(50 MW)and PV(50 MW)alongside a CFPP(330 MW),a lithium-iron phosphate energy storage system(LIPBESS)was integrated to improve the system’s load regulation flexibility.The energy storage operation strategy was formulated based on the charging and discharging priority of the LIPBESS for each basic scenario and the charging and discharging load calculation method of LIPBESS auxiliary regulation.Through optimization using the particle swarm algorithm,the optimal capacity of LIPBESS was determined to be within the 5.24-4.88 MWh range.From an economic perspective,the LIPBESS operating with CFPP as the regulating power source was 49.1% lower in capacity compared to the renewable energy-based storage mode.
基金supported in part by the Fundamental Research Funds for the Central Universities under Grant 2682023CX019National Natural Science Foundation of China under Grant U23B6007 and Grant 52307141Sichuan Science and Technology Program under Grant 2024NSFSC0115。
文摘High-frequency oscillation(HFO)of gridconnected wind power generation systems(WPGS)is one of the most critical issues in recent years that threaten the safe access of WPGS to the grid.Ensuring the WPGS can damp HFO is becoming more and more vital for the development of wind power.The HFO phenomenon of wind turbines under different scenarios usually has different mechanisms.Hence,engineers need to acquire the working mechanisms of the different HFO damping technologies and select the appropriate one to ensure the effective implementation of oscillation damping in practical engineering.This paper introduces the general assumptions of WPGS when analyzing HFO,systematically summarizes the reasons for the occurrence of HFO in different scenarios,deeply analyses the key points and difficulties of HFO damping under different scenarios,and then compares the technical performances of various types of HFO suppression methods to provide adequate references for engineers in the application of technology.Finally,this paper discusses possible future research difficulties in the problem of HFO,as well as the possible future trends in the demand for HFO damping.
文摘This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a unified power quality conditioner(UPQC).In addition to supplying active power to the utility grid,the system of hybrid wind photovoltaic functions as a UPQC,compensating reactive power and suppressing the harmonic load currents.Additionally,the load is supplied with harmonic-free,balanced and regulated output voltages.Since PVWind-UPQC is established on a dual compensation scheme,the series inverter works like a sinusoidal current source,while the parallel inverter works like a sinusoidal voltage source.Consequently,a smooth alteration from interconnected operating modes to island operating modes and vice versa can be achieved without load voltage transients.Since PV-Wind-UPQC inverters handle the energy generated through the hybrid wind photovoltaic system and the energy demanded through the load,the converters should be sized cautiously.A detailed study of the flow of power via the PV-Wind-UPQC is imperative to gain a complete understanding of the system operation and the proper design of the converters.Thus,curves that allow the sizing of the power converters according to the power flow via the converters are presented and discussed.Simulation results are presented to assess both steady state and dynamic performances of the grid connected hybrid system of PV-Wind-UPQC.This investigation is verified by simulating and analyzing the results with Matlab/Simulink.
基金supported by the National Natural Science Foundation of China(61773269)China Scholarship for Overseas Studying(CSC No.202008210181),Department of Education of Liaoning Province of China(LJKZ1110)+1 种基金the Natural Science Foundation of Liaoning Province of China(2019-KF-03-08)the Program for Shenyang High Level Innovative Talents(RC190042).
文摘Electric-heat coupling characteristics of a cogeneration system and the operating mode of fixing electricity with heat are the main reasons for wind abandonment during the heating season in the Three North area.To improve the wind-power absorption capacity and operating economy of the system,the structure of the system is improved by adding a heat storage device and an electric boiler.First,aiming at the minimum operating cost of the system,the optimal scheduling model of the cogeneration system,including a heat storage device and electric boiler,is constructed.Second,according to the characteristics of the problem,a cultural gene algorithm program is compiled to simulate the calculation example.Finally,through the system improvement,the comparison between the conditions before and after and the simulation solutions of similar algorithms prove the effectiveness of the proposed scheme.The simulation results show that adding the heat storage device and electric boiler to the scheduling optimization process not only improves the wind power consumption capacity of the cogeneration system but also reduces the operating cost of the system by significantly reducing the coal consumption of the unit and improving the economy of the system operation.The cultural gene algorithm framework has both the global evolution process of the population and the local search for the characteristics of the problem,which has a better optimization effect on the solution.
基金Project supported by the National Natural Science Foundation of China for Outstanding Youth(Grant No.51622906)the National Natural Science Foundation of China(Grant No.51479173)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.201304030577)the Scientific Research Funds of Northwest A&F University(Grant No.2013BSJJ095)the Science Fund for Excellent Young Scholars from Northwest A&F University and Shaanxi Nova Program,China(Grant No.2016KJXX-55)
文摘Internal effects of the dynamic behaviors and nonlinear characteristics of a coupled fractional order hydropower generation system(HGS) are analyzed. A mathematical model of hydro-turbine governing system(HTGS) with rigid water hammer and hydro-turbine generator unit(HTGU) with fractional order damping forces are proposed. Based on Lagrange equations, a coupled fractional order HGS is established. Considering the dynamic transfer coefficient eis variational during the operation, introduced e as a periodic excitation into the HGS. The internal relationship of the dynamic behaviors between HTGS and HTGU is analyzed under different parameter values and fractional order. The results show obvious fast–slow dynamic behaviors in the HGS, causing corresponding vibration of the system, and some remarkable evolution phenomena take place with the changing of the periodic excitation parameter values.
文摘Although transmission systems are able to cover most of the areas in many countries, there are still some isolated areas such as rural counties and remote desert lands where grid power cannot be accessed. Therefore, a reliable and economical power supply scheme is required to solve the problem. One of them combines wind/solar power generation with the support of storage system. This paper is to give an overview of the optimization methodologies about the wind/solar stand-alone system supported by storage systems or integrating with other renewable or conventional power generation sources. It is shown that continued research and optimization methodology in this area are still in great need for performance improvement.
基金supported by the National High Technology Research and Development Program of China under Grant No.2011AA05S113Major State Basic Research Development Program under Grant No.2012CB215106+1 种基金Science and Technology Plan Program in Zhejiang Province under Grant No.2009C34013National Science and Technology Supporting Plan Project under Grant No.2009BAG12A09
文摘Making full use of wind power is one of the main purposes of the wind turbine generator control. Conventional hill climbing search (HCS) method can realize the maximum power point tracking (MPPT). However, the step size of HCS method is constant so that it cannot consider both steady-state response and dynamic response. A fuzzy logical control (FLC) algorithm is proposed to solve this problem in this paper, which can track the maximum power point (MPP) quickly and smoothly. To evaluate MPPT algorithms, four performance indices are also proposed in this paper. They are the energy captured by wind turbine, the maximum power-point tracking time when wind speed changes slowly, the fluctuation magnitude of real power during steady state, and the energy captured by wind turbine when wind speed changes fast. Three cases are designed and simulated in MATLAB/Simulink respectively. The comparison of the three MPPT strategies concludes that the proposed fuzzy logical control algorithm is more superior to the conventional HCS algorithms.
文摘Due to growing concerns regarding climate change and environmental protection,smart power generation has become essential for the economical and safe operation of both conventional thermal power plants and sustainable energy.Traditional first-principle model-based methods are becoming insufficient when faced with the ever-growing system scale and its various uncertainties.The burgeoning era of machine learning(ML)and data-driven control(DDC)techniques promises an improved alternative to these outdated methods.This paper reviews typical applications of ML and DDC at the level of monitoring,control,optimization,and fault detection of power generation systems,with a particular focus on uncovering how these methods can function in evaluating,counteracting,or withstanding the effects of the associated uncertainties.A holistic view is provided on the control techniques of smart power generation,from the regulation level to the planning level.The benefits of ML and DDC techniques are accordingly interpreted in terms of visibility,maneuverability,flexibility,profitability,and safety(abbreviated as the“5-TYs”),respectively.Finally,an outlook on future research and applications is presented.
基金financially supported by the National Basic Research Program of China(973 Program,Grant No.2014CB046205)
文摘In order to investigate the aerodynamic characteristics of 6-MW wind turbine, experimental study on the aerodynamic characteristics of the model rotor system and on characterization of a wind generation system is carried out. In the test, a thrust-matched rotor system and a geometry-matched rotor system, which utilize redesigned thrustmatched and original geometry-matched blades, respectively, are applied. The 6-MW wind turbine system is introduced briefly. The proper scaling laws for model tests are established in the paper, which are then implemented in the construction of a model wind turbine with optimally designed blades. And the parameters of the model are provided. The aerodynamic characteristics of the proposed 6-MW wind rotor system are explored by testing a 1:65.3 scale model at the State Key Laboratory of Ocean Engineering at Shanghai Jiao Tong University. Before carrying out the wind rotor system test, the turbulence intensity and spatial uniformity of the wind generation system are tested and results demonstrate that the characterization of the wind generation system is satisfied and the average turbulence intensity of less than 10% within the wind rotor plane is proved in the test. And then, the aerodynamic characteristics of 6-MW wind rotor system are investigated. The response characteristic differences between the thrust-matched rotor system and the geometry-matched rotor system are presented. Results indicate that the aerodynamic characteristics of 6-MW wind rotor with the thrust-matched rotor system are satisfied. The conclusion is that the thrust-matched rotor system can better reflect the characteristics of the prototype wind turbine. A set of model test method is proposed in the work and preparations for further model basin test of the 6-MW SPAR-type floating offshore wind turbine system are made.
基金supported by the National Key R&D Program of China (2016YFC0402209)the Major Research Plan of the National Natural Science Foundation of China (No. 91647114)
文摘Due to the intermittency and instability of Wind-Solar energy and easy compensation of hydropower, this study proposes a Wind-Solar-Hydro power optimal scheduling model. This model is aimed at maximizing the total system power generation and the minimum ten-day joint output. To effectively optimize the multi-objective model, a new algorithm named non-dominated sorting culture differential evolution algorithm(NSCDE) is proposed. The feasibility of NSCDE was verified through several well-known benchmark problems. It was then applied to the Jinping Wind-Solar-Hydro complementary power generation system. The results demonstrate that NSCDE can provide decision makers a series of optimized scheduling schemes.
基金This project was supported by National Key R&D Program of China(2017YFB0601903)Beijing Science and Technology Commission Technology Collaborative Innovation Project(201100004520001)the Huaneng Clean Energy Institute(TZ-11-SST01-JY-01).
文摘The use of high-temperature fuel cells as a power technology can improve the efficiency of electricity generation and achieve near-zero emissions of carbon dioxide.This work explores the performance of a 10 kW high-temperature molten carbonate fuel cell.The key materials of a single cell were characterized and analyzed using X-ray diffraction and scanning electron microscopy.The results show that the pore size of the key electrode material is 6.5 lm and the matrix material is a-LiAlO_(2).Experimentally,the open circuit voltage of the single cell was found to be 1.23 V.The current density was greater than 100 mA/cm^(2)at an operating voltage of 0.7 V.The 10 kW fuel cell stack comprised 80 single fuel cells with a total area of 2000 cm^(2)and achieved an open circuit voltage of greater than 85 V.The fuel cell stack power and current density could reach 11.7 kW and 104.5 mA/cm2 at an operating voltage of 56 V.The influence and long-term stable operation of the stack were also analyzed and discussed.The successful operation of a 10 kW high-temperature fuel cell promotes the large-scale use of fuel cells and provides a research basis for future investigations of fuel cell capacity enhancement and distributed generation in China.
文摘The global Electricity Sector and its customers are faced with a number of challenges that are unparalleled since the advent of widespread electrification. Challenges including climate change, escalating energy prices, energy security and energy efficiency are converging to drive fundamental change in the way energy is produced, delivered and utilized. The electricity system of the future must produce and distribute electricity that is reliable, affordable and clean. To accomplish these goals, both the electricity grid and the existing regulatory system must be smarter. This paper explores smart grid technologies, distributed generation systems, R & D efforts across Europe and the United States, and technical, economical and regulatory barriers facing modern utilities.
基金The authors thank for the project of the National Key Research and development(R&D)Program and International Science and Technology Innovation Project between Governments(2021YFE0108900)Pujiang Talent Program Supported by Fund of Shanghai Science and Technology Committee(project code:20PJ1402800)supported by Innovative Science and Technology Initiative for Security(Ministry of Defence,Japan).
文摘Disaster-hit and/or un-electrifed remote areas usually have electricity accessibility issues and an abundance of plant-derived debris and wood from destroyed wooden structures;this can be potentially addressed by employing a decentralized ultrasmall biomass-fed gasifcation power generating system.This paper presents an assessment of the technical viability of an ultra-small gasifcation system that utilizes densifed carbonized wood pellets/briquettes.The setup was run continuously for 100 h.A variety of biomass was densifed and carbonized by harnessing fugitive heat sources before charging into the reactor.Carbonized briquettes and furnished blends exhibited inferior gasifcation performance compared to the carbonized pellets.In the absence of tar blockage problems,steady-state conditions were achieved when pre-treated feedstock was used.Under steady-state conditions for carbonized pellets gasifcation operated at an equivalence ratio of 0.32,cold gas efciency and carbon conversion achieved 49.2%and 70.5%,respectively.Overall efciency and maximum power output of 20.3%and 21 kW were realised,respectively.It was found that the system could keep stable while the low heating valve of syngas was over 4 MJ/m^(3)on condition that avoiding tar blocking issues.The results indicate that the proposed compact ultra-small power generation system is a technically feasible approach to remedy power shortage challenge.In addition,process simulation considering carbonized wood gasifcation combined power generation was formulated to produce syngas and electricity.Woody pellets with the fow rate of 20 kg/h could generate a 15.18 kW power at the air fow rate of 40 Nm^(3)/h,which is in a good agreement with 15 kW in the 100 h operation.It is indicated that the gasifcation combined power generation cycle simulated by Aspen simulator could achieve reliable data to assist the complicated experiment operation.
文摘Last decade witnessed tremendous research and development in the area of photo-electrolytic hydrogen generation using chemically stable nanostructured photo-cathode/anode materials. Due to intimately coupled charge separation and photo-catalytic processes, it is very difficult to optimize individual components of such system leading to a very low demonstrated solar-to-fuel efficiency (SFE) of less than 1%. Recently there has been growing interest in an integrated photovoltaic–electrochemical (PV–EC) system based on GaAs solar cells with the demonstrated SFE of 24.5% under concentrated illumination condition. But a high cost of GaAs based solar cells and recent price drop of poly-crystalline silicon (pc-Si) solar cells motivated researchers to explore silicon based integrated PV–EC system. In this paper a theoretical framework is introduced to model silicon-based integrated PV–EC device. The theoretical framework is used to analyze the coupling and kinetic losses of a silicon solar cell based integrated PV–EC water splitting system under varying temperature and illumination. The kinetic loss occurs in the range of 19.1%–27.9% and coupling loss takes place in the range of 5.45%–6.74% with respect to varying illumination in the range of 20–100?mW/cm2. Similarly, the effect of varying temperature has severe impact on the performance of the system, wherein the coupling loss occurs in the range of 0.84%–21.51% for the temperature variation from 25 to 50?°C. ? 2016 Science Press
基金Sponsored by Natural Sclence Foundation of China.
文摘Formal methods for test sequence generation from FSM have been studied widely andthoroughly,but most real communication systems can only be modeled as EFSM exactly.Data portion in EFSM brings difficulties for test suite generation.In this paper,the strategyof generating test suite from protocols modelled as EFSM is presented.This strategy consid-ers testing of both the control portion and data portion of protocols.A software,the testsuite generation system(TSGS)based on above strategy,is introduced.
文摘Paraphrase is an expression of a text with alternative words and orders to achieve a better clarity. Paraphrases have been found vital for augmenting training dataset, which aid to enhance performance of machine learning models that intended for various natural language processing (NLP) tasks. Thus, recently, automatic paraphrase generation has received increasing attention. However, evaluating quality of generated paraphrases is technically challenging. In the literature, the importance of generated paraphrases is tended to be determined by their impact on the performance of other NLP tasks. This kind of evaluation is referred as extrinsic evaluation, which requires high computational resources to train and test the models. So far, very little attention has been paid to the role of intrinsic evaluation in which quality of generated paraphrase is judged against predefined ground truth (reference paraphrases). In fact, it is also very challenging to find ideal and complete reference paraphrases. Therefore, in this study, we propose semantic or meaning oriented automatic evaluation metric that helps to evaluate quality of generated paraphrases against the original text, which is an intrinsic evaluation approach. Further, we evaluate quality of the paraphrases by assessing their impact on other NLP tasks, which is an extrinsic evaluation method. The goal is to explore the relationship between intrinsic and extrinsic evaluation methods. To ensure the effectiveness of proposed evaluation methods, extensive experiments are done on different publicly available datasets. The experimental results demonstrate that our proposed intrinsic and extrinsic evaluation strategies are promising. The results further reveal that there is a significant correlation between intrinsic and extrinsic evaluation approaches.
文摘Coal, petroleum and natural gas will still be the basis of economic development for a long time. However, with a rapider consumption speed, these fossil fuels will be exhausted in the near future. In addition, the usage of these fossil fuels can also cause environmental pollution and greenhouse effect. To deal with energy security and environmental crisis, it is wise to work towards three directions: energy saving and emission reduction, energy recovery, exploration of new renewable energy. Currently, the electricity generation technology using piezoelectric material to recover the compressional or vibrational energy begins to draw attention. However, most of the researches are devoted to designing small self-powered devices. This paper presents an overview of the feasibility of piezoelectric power generation system for electric power system, in which the fundamentals of piezoelectric power generation and the feasible structure of the system are discussed.
文摘In this study, a circular plate that is installing a piezoelectric element at its center is adopted as energy-harvesting system and is subjected to a harmonic point force. Because this system cannot avoid the influence of its acoustic radiation, the influence is considered theoretically using the equation of plate motion taking into account its radiation impedance and is estimated by the electricity generation efficiency, which is derived from the ratio of the electric power in the electricity generation and the mechanical power supplied to the plate. As a result, the efficiency is suppressed by the acoustic radiation from the plate, so that the efficiencies are so different in whether to take into consideration the radiation impedance or not. Because those results are verified by the electricity generation experiment and radiation acoustic energy has a hopeful prospect for improving the performance of this system, mechanical-acoustic coupling is used to make the most of the acoustic energy. Therefore, a cylinder that has the above plates at both ends is also adopted as the electricity generation system and mechanical-acoustic coupling is caused between the plate vibrations and an internal sound field into the cylindrical enclosure by subjecting one side of each plate to a harmonic point force. Then, the effect of coupling is evaluated by comparing with the efficiencies in the electricity generation system of only plate. Specifically, because the radiation impedance increases with the plate thickness, i.e., with the natural frequency of the plate, it is demonstrated that the effect of coupling becomes remarkable with increasing the thickness on the electricity generation efficiency.
文摘A laboratory system was designed to generate bitumen fumes and expose tested samplers in a homogenised chamber. The system was also designed to condense the fumes in the form of oil that could be used as a standard for further analytical method development. The laboratory system was evaluated in terms of stability, repeatability, aging, and ranges, focusing on the quality and quantity of the fumes and their physical characteristics. The fumes generated with the laboratory system were also compared to fumes emitted at workplaces to evaluate their similarity. The results demonstrated that laboratory fume generation was stable and repeatable. Humidity ranged from 20% to 80% RH and the total fume concentration ranged from 0.01 to 9.36 mg.m<sup>-3</sup>, covering the conditions encountered for road paving worksites. The fumes generated in the laboratory were found to be similar to those of workplaces, with slight differences in light compounds equivalent to C12 and below n-alkanes. Thus, the system designed in this study is considered capable of generating bitumen fumes used to develop sampling and analysis methods.
文摘This research is based on the detailed design and study of a plant power generation system for green building roofs based on the combination of bionics and design science.The selection of power generation plants is carried out through experiments and research,and based on which the connection between the plant power generation unit and the internal circuit of the building is studied to generate a complete building roof plant power generation system.