Renewable energy is becoming more attractive as traditional fossil fuels are rapidly depleted and expensive,and their use would release pollutants.Power systems that use both wind and solar energy are more reliable an...Renewable energy is becoming more attractive as traditional fossil fuels are rapidly depleted and expensive,and their use would release pollutants.Power systems that use both wind and solar energy are more reliable and efficient than those that utilize only one energy.Hybrid renewable energy systems(HRES)are viable for remote areas operating in standalone mode.This paper aims to present the state-of-the-art research on off-grid solar-wind hybrid energy systems over the last two decades.More than 1500 published articles extracted from the Web of Science are analyzed by bibliometric methods and processed by CiteSpace to present the results with figures and tables.Productive countries and highly cited authors are identified,and hot topics with hotspot articles are shown in landscape and timeline views.Emerging trends and new developments related to techno-economic analysis and microgrids,as well as the application of HOMER software,are predicted based on the analysis of citation bursts.Furthermore,the opportunities of hybrid energy systems for sustainable development are discussed,and challenges and possible solutions are proposed.The study of this paper provides researchers with a comprehensive understanding and intuitive representation of standalone solar-wind hybrid energy systems.展开更多
针对如何精确取得基于飞思卡尔i.MX31硬件平台下WMA(Windows Media Audio)Decoder的运行性能,提高其执行效率这一课题,搭建了Standalone开发平台。搭建该平台的关键是如何配置i.MX31中的MMU(Memory Management Unit)。我们目前采用段存...针对如何精确取得基于飞思卡尔i.MX31硬件平台下WMA(Windows Media Audio)Decoder的运行性能,提高其执行效率这一课题,搭建了Standalone开发平台。搭建该平台的关键是如何配置i.MX31中的MMU(Memory Management Unit)。我们目前采用段存储块机制实现MMU。通过对在该平台下WMA Decoder实验数据的分析,已经精确地取得了项目的性能,而且运行效率也提高了29%。展开更多
Battery energy storage systems,fuel cells,and photovoltaic generators are being adopted in distribution networks to achieve CO;emission reduction.These power sources require inverters to connect to AC networks.However...Battery energy storage systems,fuel cells,and photovoltaic generators are being adopted in distribution networks to achieve CO;emission reduction.These power sources require inverters to connect to AC networks.However,sub-networks,such as a microgrids containing inverter power sources,may be disconnected from the utility network and operated in a standalone mode during extended blackouts.This study focuses on a standalone microgrid supplied by inverter power sources without a synchronous generator and proposes a new microgrid inverter control.In this inverter control,a single grid forming inverter is operated as a master power source to determine frequency and voltage,and other inverters,called grid following inverters,are operated as subordinate power sources with active and reactive power control.The necessary functions in the energy management system are examined,and the coordinated operation of all inverters in the microgrid is demonstrated via simulation.展开更多
Employing the full versions of GIS software with its numerous functions to manage case-specific applications is becoming inconvenient for many reasons. A convenient solution that is spreading worldwide to solve this p...Employing the full versions of GIS software with its numerous functions to manage case-specific applications is becoming inconvenient for many reasons. A convenient solution that is spreading worldwide to solve this problem is to develop customized tools that use the same GIS concept to meet specific applications. The water resource department in Gaza strip has been facing technical and financial difficulties in using the full GIS versions in managing groundwater resources. Thus, the objective of this paper was to develop a customized standalone GIS-Based ground water quality assessment tool (GWQAT) to be used by the water resources management department in Gaza strip. GWQAT was developed using Microsoft visual basic programming language, a regression mathematical model, map objects, and map files generated from ESRI ARC Info. GWQAT was designed to achieve many functions such as mapping, map overlaying, buffering, charting, soil hydro-geological profiling, and predicting future groundwater quality parameters variations. The simplicity and validity of GWQAT was demonstrated by its application on the groundwater quality parameters in Gaza strip wells with emphasis on chloride concentration.展开更多
<span style="font-family:Verdana;">This work presents the results of the characterization of a standalone photovoltaic system for the electrification of a household located in rural area in the western...<span style="font-family:Verdana;">This work presents the results of the characterization of a standalone photovoltaic system for the electrification of a household located in rural area in the western region of Cameroon: Nziih-Bafou in Dschang (5.35</span><span style="white-space:normal;background-color:#FFFFFF;font-family:Verdana;">°</span><span style="font-family:Verdana;">N, 10.05</span><span style="white-space:normal;background-color:#FFFFFF;font-family:Verdana;">°</span><span style="font-family:Verdana;">E and 1900 m). In order to cope with the</span><span "=""> </span><span style="font-family:Verdana;">maintenance charges and reduce the investment cost, a small mill was added to the appliances of the household for income generation. The assessment of the energy demand was made by taking into account the reactive energy due to the heavy</span><span "=""> </span><span style="font-family:Verdana;">consumption of energy by the mill’s motor, especially during ignition. The sizing of all the system’s components was carried out with the prospect of determining an optimum design in accordance with daily electricity demand, site irradiance profile and climatic conditions. In this context, tilt angles applicable to the PV structure and that allow</span><span "=""> </span><span style="font-family:Verdana;">to receive the maximum irradiance as a function of the periods of the year were determined using the Hay model.</span><span "=""> </span><span style="font-family:Verdana;">This approach provides the system with incident irradiance greater than or at the limit equal to that received by a horizontal surface on the same site</span><span "=""> </span><span style="font-family:Verdana;">compared to the case of a single tilt angle where the irradiance on the inclined plane is often lower than that</span><span "=""> </span><span "=""><span style="font-family:Verdana;">on the horizontal. The economic analysis of the PV system showed an </span><span style="font-family:Verdana;">initial cost of $4448</span></span><span "=""> </span><span style="font-family:Verdana;">and the Life Cost Cycle amounted to $24,495. This</span><span style="font-family:Verdana;"> amount corresponds to a present cost per kilowatt hour of $0.44. The Net Present Value</span><span "=""> </span><span style="font-family:Verdana;">(NPV) of the project ($7793) over its lifetime (20 years)</span><span "=""> </span><span style="font-family:Verdana;">shows a payback period of less than 4 years.</span>展开更多
The literature on multi-attribute optimization for renewable energy source(RES)placement in deregulated power markets is extensive and diverse in methodology.This study focuses on the most relevant publications direct...The literature on multi-attribute optimization for renewable energy source(RES)placement in deregulated power markets is extensive and diverse in methodology.This study focuses on the most relevant publications directly addressing the research problem at hand.Similarly,while the body of work on optimal location and sizing of renewable energy generators(REGs)in balanced distribution systems is substantial,only the most pertinent sources are cited,aligning closely with the study’s objective function.A comprehensive literature review reveals several key research areas:RES integration,RES-related optimization techniques,strategic placement of wind and solar generation,and RES promotion in deregulated powermarkets,particularly within transmission systems.Furthermore,the optimal location and sizing of REGs in both balanced and unbalanced distribution systems have been extensively studied.RESs demonstrate significant potential for standalone applications in remote areas lacking conventional transmission and distribution infrastructure.Also presents a thorough review of current modeling and optimization approaches for RES-based distribution system location and sizing.Additionally,it examines the optimal positioning,sizing,and performance of hybrid and standalone renewable energy systems.This paper provides a comprehensive review of current modeling and optimization approaches for the location and sizing of Renewable Energy Sources(RESs)in distribution systems,focusing on both balanced and unbalanced networks.展开更多
Partly because of advances in power electronic converters,the share of renewable energy in power generation is steadily increasing.The main medium of interface for integrating renewable energy sources to the utility g...Partly because of advances in power electronic converters,the share of renewable energy in power generation is steadily increasing.The main medium of interface for integrating renewable energy sources to the utility grid is the power electronic inverter.Virtual oscillator control(VOC)is a time-domain approach for controlling parallel inverters in a standalone microgrid(MG).The concept is to simulate nonlinear deadzone oscillator dynamics in a system of invert-ers to ensure a stable AC MG in the absence of communication.VOC is a time-domain and self-synchronizing control-ler that simply requires the measurement of filter current,whereas traditional droop control and the virtual synchro-nous machine(VSM)require low pass filters for active and reactive power calculations.In this work,a particle swarm optimization(PSO)-based VOC method(VOC-PSO)is proposed,in which the parameters of the VOC are designed using the PSO algorithm.The system performance using droop,VSM,VOC,and VOC-PSO controllers are investigated using MATLAB and Opal-RT real-time digital simulator platforms.The results show that the proposed VOC-PSO gives improved performance over other control strategies.The efficacy of the proposed VOC-PSO control method is also demonstrated by the experimental results.展开更多
Solar and wind energy are two of the most viable and sustainable sources of energy due to the tendency of renewal. The power generating supplies in Nigeria appear unreliable, rapidly diminishing and expensive. Researc...Solar and wind energy are two of the most viable and sustainable sources of energy due to the tendency of renewal. The power generating supplies in Nigeria appear unreliable, rapidly diminishing and expensive. Researches are sparse on operating both energy sources alongside fossil fuel for power generation in order to take advantage of their complementary characters. The aim of this study is to explore renewable sources combined with non-renewable source to generate electricity with the objective of establishing an optimal design for a hybrid solar-wind-diesel energy plant that minimizes cost. The capacity factor of the standalone system was determined for the study area. The cost of energy for the hybrid optimal mix was determined. Levelised cost of energy was also used to determine the cost of energy for standalone power system. The result shows that the energy generated 200 MW hybrid system is 392 GWh with a cost of energy of $0.24/kWh (47.8/kWh). The energy produced can power 39,200 homes in a year. The optimisation shows that the number of solar system, wind and diesel are 699, 1 and 300 respectively. The cost of energy for the standalone system was $0.06/kWh, $0.08/kWh and $0.27/kWh for wind, solar and diesel system. The capacity factor was 56%, 21% and 80% for wind, solar and diesel system. There is a reduction in the amount of greenhouse gases released to the environment alongside with cost of energy generation. Hybrid power generation system is good and effective solution for power generation than conventional energy resources.展开更多
Industrial timer requirements are multifaceted. On-delay, off-delay, cyclic or sequential timing requirements, with usual time range varying from seconds to days, depending on the process. Custom build timers cannot p...Industrial timer requirements are multifaceted. On-delay, off-delay, cyclic or sequential timing requirements, with usual time range varying from seconds to days, depending on the process. Custom build timers cannot provide all of these requirements simultaneously and hence an advanced timer rectifying this shortcoming has been designed and fabricated in this work. This timer is based on the real time clock chip used in mother boards. Our design can be programmed for a specific time requirement and can later be put to work in standalone mode. A demonstration board is fabricated and tested.展开更多
Battery based standalone SHS （solar home systems） are installed in Malawi to expedite rural electrification. A study was conducted to analyze the performance of SHS in low and high insolation areas of Malawi. It is ...Battery based standalone SHS （solar home systems） are installed in Malawi to expedite rural electrification. A study was conducted to analyze the performance of SHS in low and high insolation areas of Malawi. It is found that if the system is designed in accordance to procedures stipulated in Malawi standards, then it is capable of operating annually with mean performance ratio of 0.68, PV array production factor of 0.88 and system efficiency of 78% indicating a good system performance. The system is more reliable in high insulation areas （loss of load probability = 0.09） and when the battery charging is given priority during daytime, the overall system＇s reliability is improved by 40%. However, if the system is under-designed its performance ratio is reduced considerably and the system becomes less reliable. In overall, SHS in Malawi perform reliably if the system is well designed and maintained.展开更多
The aim of this paper is the evaluation of the performance of a low pressure PEM （proton exchange membrane） fuel cell stack to step load changes, which are characteristic of standalone fuel cell system applications....The aim of this paper is the evaluation of the performance of a low pressure PEM （proton exchange membrane） fuel cell stack to step load changes, which are characteristic of standalone fuel cell system applications. The goal is a better understanding of the electrical behavior of the FC （fuel cell）, as a result of the electrochemical processes, via the cell＇s voltage characteristic during transient response. While changing the load, the performance of significant parameters affected such as temperature, pressure, purge status etc. are registered and evaluated. The analysis and experiment are based on a low pressure 1.2 kW PEM fuel cell stack （NEXAS power module）. Then, the experiment is simulated using Matlab/Simulink tools, while PCU （power conditioning units） are added in order to control power flow for enhanced performance. Finally, both operational and simulation data are compared to each other showing that simple PCUs applications can improve system＇s efficiency.展开更多
The standalone hybrid power system constitu- tes a synchronous generator driven by a diesel engine, renewable energy source （wind） apart from a battery energy storage system. A coherent control strategy to regulate ...The standalone hybrid power system constitu- tes a synchronous generator driven by a diesel engine, renewable energy source （wind） apart from a battery energy storage system. A coherent control strategy to regulate the voltage and frequency of the standalone grid is proposed in this paper. The system is simulated using Matlab/Simulink for preliminary validation and further tested on a laboratory prototype which involves a TMS320LF2407A DSP controller to digitally implement the control strategy. The dynamic behavior of the system is perused through the direct connection of an induction machine. The control strategy is verified for step changes in load and variation in wind power.展开更多
基金This work was supported by Education Department of Hunan Province,China under Grant 22C013(Q.Zhou received this grant and the sponsor’s websites is https://jyt.hunan.gov.cn/).
文摘Renewable energy is becoming more attractive as traditional fossil fuels are rapidly depleted and expensive,and their use would release pollutants.Power systems that use both wind and solar energy are more reliable and efficient than those that utilize only one energy.Hybrid renewable energy systems(HRES)are viable for remote areas operating in standalone mode.This paper aims to present the state-of-the-art research on off-grid solar-wind hybrid energy systems over the last two decades.More than 1500 published articles extracted from the Web of Science are analyzed by bibliometric methods and processed by CiteSpace to present the results with figures and tables.Productive countries and highly cited authors are identified,and hot topics with hotspot articles are shown in landscape and timeline views.Emerging trends and new developments related to techno-economic analysis and microgrids,as well as the application of HOMER software,are predicted based on the analysis of citation bursts.Furthermore,the opportunities of hybrid energy systems for sustainable development are discussed,and challenges and possible solutions are proposed.The study of this paper provides researchers with a comprehensive understanding and intuitive representation of standalone solar-wind hybrid energy systems.
文摘Battery energy storage systems,fuel cells,and photovoltaic generators are being adopted in distribution networks to achieve CO;emission reduction.These power sources require inverters to connect to AC networks.However,sub-networks,such as a microgrids containing inverter power sources,may be disconnected from the utility network and operated in a standalone mode during extended blackouts.This study focuses on a standalone microgrid supplied by inverter power sources without a synchronous generator and proposes a new microgrid inverter control.In this inverter control,a single grid forming inverter is operated as a master power source to determine frequency and voltage,and other inverters,called grid following inverters,are operated as subordinate power sources with active and reactive power control.The necessary functions in the energy management system are examined,and the coordinated operation of all inverters in the microgrid is demonstrated via simulation.
文摘Employing the full versions of GIS software with its numerous functions to manage case-specific applications is becoming inconvenient for many reasons. A convenient solution that is spreading worldwide to solve this problem is to develop customized tools that use the same GIS concept to meet specific applications. The water resource department in Gaza strip has been facing technical and financial difficulties in using the full GIS versions in managing groundwater resources. Thus, the objective of this paper was to develop a customized standalone GIS-Based ground water quality assessment tool (GWQAT) to be used by the water resources management department in Gaza strip. GWQAT was developed using Microsoft visual basic programming language, a regression mathematical model, map objects, and map files generated from ESRI ARC Info. GWQAT was designed to achieve many functions such as mapping, map overlaying, buffering, charting, soil hydro-geological profiling, and predicting future groundwater quality parameters variations. The simplicity and validity of GWQAT was demonstrated by its application on the groundwater quality parameters in Gaza strip wells with emphasis on chloride concentration.
文摘<span style="font-family:Verdana;">This work presents the results of the characterization of a standalone photovoltaic system for the electrification of a household located in rural area in the western region of Cameroon: Nziih-Bafou in Dschang (5.35</span><span style="white-space:normal;background-color:#FFFFFF;font-family:Verdana;">°</span><span style="font-family:Verdana;">N, 10.05</span><span style="white-space:normal;background-color:#FFFFFF;font-family:Verdana;">°</span><span style="font-family:Verdana;">E and 1900 m). In order to cope with the</span><span "=""> </span><span style="font-family:Verdana;">maintenance charges and reduce the investment cost, a small mill was added to the appliances of the household for income generation. The assessment of the energy demand was made by taking into account the reactive energy due to the heavy</span><span "=""> </span><span style="font-family:Verdana;">consumption of energy by the mill’s motor, especially during ignition. The sizing of all the system’s components was carried out with the prospect of determining an optimum design in accordance with daily electricity demand, site irradiance profile and climatic conditions. In this context, tilt angles applicable to the PV structure and that allow</span><span "=""> </span><span style="font-family:Verdana;">to receive the maximum irradiance as a function of the periods of the year were determined using the Hay model.</span><span "=""> </span><span style="font-family:Verdana;">This approach provides the system with incident irradiance greater than or at the limit equal to that received by a horizontal surface on the same site</span><span "=""> </span><span style="font-family:Verdana;">compared to the case of a single tilt angle where the irradiance on the inclined plane is often lower than that</span><span "=""> </span><span "=""><span style="font-family:Verdana;">on the horizontal. The economic analysis of the PV system showed an </span><span style="font-family:Verdana;">initial cost of $4448</span></span><span "=""> </span><span style="font-family:Verdana;">and the Life Cost Cycle amounted to $24,495. This</span><span style="font-family:Verdana;"> amount corresponds to a present cost per kilowatt hour of $0.44. The Net Present Value</span><span "=""> </span><span style="font-family:Verdana;">(NPV) of the project ($7793) over its lifetime (20 years)</span><span "=""> </span><span style="font-family:Verdana;">shows a payback period of less than 4 years.</span>
文摘The literature on multi-attribute optimization for renewable energy source(RES)placement in deregulated power markets is extensive and diverse in methodology.This study focuses on the most relevant publications directly addressing the research problem at hand.Similarly,while the body of work on optimal location and sizing of renewable energy generators(REGs)in balanced distribution systems is substantial,only the most pertinent sources are cited,aligning closely with the study’s objective function.A comprehensive literature review reveals several key research areas:RES integration,RES-related optimization techniques,strategic placement of wind and solar generation,and RES promotion in deregulated powermarkets,particularly within transmission systems.Furthermore,the optimal location and sizing of REGs in both balanced and unbalanced distribution systems have been extensively studied.RESs demonstrate significant potential for standalone applications in remote areas lacking conventional transmission and distribution infrastructure.Also presents a thorough review of current modeling and optimization approaches for RES-based distribution system location and sizing.Additionally,it examines the optimal positioning,sizing,and performance of hybrid and standalone renewable energy systems.This paper provides a comprehensive review of current modeling and optimization approaches for the location and sizing of Renewable Energy Sources(RESs)in distribution systems,focusing on both balanced and unbalanced networks.
基金supported by DST project Scheme for Young Scientists and Technologists (SP/YO/2019/1349).
文摘Partly because of advances in power electronic converters,the share of renewable energy in power generation is steadily increasing.The main medium of interface for integrating renewable energy sources to the utility grid is the power electronic inverter.Virtual oscillator control(VOC)is a time-domain approach for controlling parallel inverters in a standalone microgrid(MG).The concept is to simulate nonlinear deadzone oscillator dynamics in a system of invert-ers to ensure a stable AC MG in the absence of communication.VOC is a time-domain and self-synchronizing control-ler that simply requires the measurement of filter current,whereas traditional droop control and the virtual synchro-nous machine(VSM)require low pass filters for active and reactive power calculations.In this work,a particle swarm optimization(PSO)-based VOC method(VOC-PSO)is proposed,in which the parameters of the VOC are designed using the PSO algorithm.The system performance using droop,VSM,VOC,and VOC-PSO controllers are investigated using MATLAB and Opal-RT real-time digital simulator platforms.The results show that the proposed VOC-PSO gives improved performance over other control strategies.The efficacy of the proposed VOC-PSO control method is also demonstrated by the experimental results.
文摘Solar and wind energy are two of the most viable and sustainable sources of energy due to the tendency of renewal. The power generating supplies in Nigeria appear unreliable, rapidly diminishing and expensive. Researches are sparse on operating both energy sources alongside fossil fuel for power generation in order to take advantage of their complementary characters. The aim of this study is to explore renewable sources combined with non-renewable source to generate electricity with the objective of establishing an optimal design for a hybrid solar-wind-diesel energy plant that minimizes cost. The capacity factor of the standalone system was determined for the study area. The cost of energy for the hybrid optimal mix was determined. Levelised cost of energy was also used to determine the cost of energy for standalone power system. The result shows that the energy generated 200 MW hybrid system is 392 GWh with a cost of energy of $0.24/kWh (47.8/kWh). The energy produced can power 39,200 homes in a year. The optimisation shows that the number of solar system, wind and diesel are 699, 1 and 300 respectively. The cost of energy for the standalone system was $0.06/kWh, $0.08/kWh and $0.27/kWh for wind, solar and diesel system. The capacity factor was 56%, 21% and 80% for wind, solar and diesel system. There is a reduction in the amount of greenhouse gases released to the environment alongside with cost of energy generation. Hybrid power generation system is good and effective solution for power generation than conventional energy resources.
文摘Industrial timer requirements are multifaceted. On-delay, off-delay, cyclic or sequential timing requirements, with usual time range varying from seconds to days, depending on the process. Custom build timers cannot provide all of these requirements simultaneously and hence an advanced timer rectifying this shortcoming has been designed and fabricated in this work. This timer is based on the real time clock chip used in mother boards. Our design can be programmed for a specific time requirement and can later be put to work in standalone mode. A demonstration board is fabricated and tested.
文摘Battery based standalone SHS （solar home systems） are installed in Malawi to expedite rural electrification. A study was conducted to analyze the performance of SHS in low and high insolation areas of Malawi. It is found that if the system is designed in accordance to procedures stipulated in Malawi standards, then it is capable of operating annually with mean performance ratio of 0.68, PV array production factor of 0.88 and system efficiency of 78% indicating a good system performance. The system is more reliable in high insulation areas （loss of load probability = 0.09） and when the battery charging is given priority during daytime, the overall system＇s reliability is improved by 40%. However, if the system is under-designed its performance ratio is reduced considerably and the system becomes less reliable. In overall, SHS in Malawi perform reliably if the system is well designed and maintained.
文摘The aim of this paper is the evaluation of the performance of a low pressure PEM （proton exchange membrane） fuel cell stack to step load changes, which are characteristic of standalone fuel cell system applications. The goal is a better understanding of the electrical behavior of the FC （fuel cell）, as a result of the electrochemical processes, via the cell＇s voltage characteristic during transient response. While changing the load, the performance of significant parameters affected such as temperature, pressure, purge status etc. are registered and evaluated. The analysis and experiment are based on a low pressure 1.2 kW PEM fuel cell stack （NEXAS power module）. Then, the experiment is simulated using Matlab/Simulink tools, while PCU （power conditioning units） are added in order to control power flow for enhanced performance. Finally, both operational and simulation data are compared to each other showing that simple PCUs applications can improve system＇s efficiency.
文摘The standalone hybrid power system constitu- tes a synchronous generator driven by a diesel engine, renewable energy source （wind） apart from a battery energy storage system. A coherent control strategy to regulate the voltage and frequency of the standalone grid is proposed in this paper. The system is simulated using Matlab/Simulink for preliminary validation and further tested on a laboratory prototype which involves a TMS320LF2407A DSP controller to digitally implement the control strategy. The dynamic behavior of the system is perused through the direct connection of an induction machine. The control strategy is verified for step changes in load and variation in wind power.
