Fault Ride-Through （FRT） capabilities set up according to the grid codes may affect the performance of related protective elements during fault periods. Therefore, in this paper the coordination between the FRT capa...Fault Ride-Through （FRT） capabilities set up according to the grid codes may affect the performance of related protective elements during fault periods. Therefore, in this paper the coordination between the FRT capability and over-current protection of DFIG Wind Generators in MV networks is investigated. Simulation test cases using MATLAB-Simulink are implemented on a 365-MW wind farm in AL-Zaafarana, Egypt. The simulation results show the influence of the FRT capability on the protective relaying coordination in wind farms, showing that the FRT may work in situations where is were expected not to work, and then disabling the over-current protection, which should have worked in this situation.展开更多
We give a new result on the construction of K-frame generators for unitary systems by using the pseudo-inverses of involved operators,which provides an improvement to one known result on this topic.We also introduce t...We give a new result on the construction of K-frame generators for unitary systems by using the pseudo-inverses of involved operators,which provides an improvement to one known result on this topic.We also introduce the concept of K-woven generators for unitary systems,by means of which we investigate the weaving properties of K-frame generators for unitary systems.展开更多
This review paper examines the various types of electrical generators used to convert wave energy into electrical energy.The focus is on both linear and rotary generators,including their design principles,operational ...This review paper examines the various types of electrical generators used to convert wave energy into electrical energy.The focus is on both linear and rotary generators,including their design principles,operational efficiencies,and technological advancements.Linear generators,such as Induction,permanent magnet synchronous,and switched reluctance types,are highlighted for their direct conversion capability,eliminating the need for mechanical gearboxes.Rotary Induction generators,permanent magnet synchronous generators,and doubly-fed Induction generators are evaluated for their established engineering principles and integration with existing grid infrastructure.The paper discusses the historical development,environmental benefits,and ongoing advancements in wave energy technologies,emphasizing the increasing feasibility and scalability of wave energy as a renewable source.Through a comprehensive analysis,this review provides insights into the current state and future prospects of electrical generators in wave energy conversion,underscoring their potential to significantly reduce reliance on fossil fuels and mitigate environmental impacts.展开更多
To address the excessive complexity of monthly scheduling and the impact of uncertain net load on the chargeable energy of storage,a reduced time-period monthly scheduling model for thermal generators and energy stora...To address the excessive complexity of monthly scheduling and the impact of uncertain net load on the chargeable energy of storage,a reduced time-period monthly scheduling model for thermal generators and energy storage,incorporating daily minimum chargeable energy constraints,was developed.Firstly,considering the variations in the frequency of unit start-ups and shutdowns under different levels of net load fluctuation,a method was proposed to reduce decision time periods for unit start-up and shut-down operations.This approach,based on the characteristics of net load fluctuations,minimizes the decision variables of units,thereby simplifying the monthly schedulingmodel.Secondly,the relationship between energy storage charging and discharging power,net load,and the total maximum/minimum output of units was analyzed.Based on this,daily minimum chargeable energy constraints were established to ensure the energy storage system meets charging requirements under extreme net load scenarios.Finally,taking into account the operational costs of thermal generators and energy storage,load loss costs,and operational constraints,the reduced time-period monthly schedulingmodel was constructed.Case studies demonstrate that the proposedmethod effectively generates economical monthly operation plans for thermal generators and energy storage,significantly reduces model solution time,and satisfies the charging requirements of energy storage under extreme net load conditions.展开更多
背景全科医生的培养和发展始终是医学界关注的焦点,而各国对全科医生的培训模式和方法存在显著的差异。目的总结并揭示我国全科医生培养的热点、趋势以及挑战,同时对比国外做法,为我国全科医生的未来发展提供借鉴和指导。方法采用文献...背景全科医生的培养和发展始终是医学界关注的焦点,而各国对全科医生的培训模式和方法存在显著的差异。目的总结并揭示我国全科医生培养的热点、趋势以及挑战,同时对比国外做法,为我国全科医生的未来发展提供借鉴和指导。方法采用文献计量学的方法,以CiteSpace 6.1.R Advanced软件为工具,国内研究分析基于中国知网(CNKI),国外研究分析选取Web of Science核心数据库(WOSCC),对2013—2023年国内外全科医生培养的文献进行筛选与定量化分析,并归纳总结。结果我国全科医生教育的研究数量逐年增长;我国研究机构以首都医科大学全科医学与继续教育学院发文量最多,但各机构间的合作不紧密;国外主要发文国家为英国和澳大利亚;我国全科医生培养研究偏向于教育方法改革和服务方向优化,而同期国外全科医生培养的研究侧重于人工智能技术的应用和对精神心理疾病的关注。结论我国全科医生培养的研究活动增长显著,集中在教育方法改革和服务方向优化,但各研究机构间需加强合作。对比国外研究模式,我国需要更多地引入新兴技术(如人工智能),并提升对精神心理疾病的关注度,以促进全科医生培养的深度和广度发展。展开更多
文摘Fault Ride-Through （FRT） capabilities set up according to the grid codes may affect the performance of related protective elements during fault periods. Therefore, in this paper the coordination between the FRT capability and over-current protection of DFIG Wind Generators in MV networks is investigated. Simulation test cases using MATLAB-Simulink are implemented on a 365-MW wind farm in AL-Zaafarana, Egypt. The simulation results show the influence of the FRT capability on the protective relaying coordination in wind farms, showing that the FRT may work in situations where is were expected not to work, and then disabling the over-current protection, which should have worked in this situation.
基金Supported by NSFC(Nos.12361028,11761057)Science Foundation of Jiangxi Education Department(Nos.GJJ202302,GJJ202303,GJJ202319).
文摘We give a new result on the construction of K-frame generators for unitary systems by using the pseudo-inverses of involved operators,which provides an improvement to one known result on this topic.We also introduce the concept of K-woven generators for unitary systems,by means of which we investigate the weaving properties of K-frame generators for unitary systems.
文摘This review paper examines the various types of electrical generators used to convert wave energy into electrical energy.The focus is on both linear and rotary generators,including their design principles,operational efficiencies,and technological advancements.Linear generators,such as Induction,permanent magnet synchronous,and switched reluctance types,are highlighted for their direct conversion capability,eliminating the need for mechanical gearboxes.Rotary Induction generators,permanent magnet synchronous generators,and doubly-fed Induction generators are evaluated for their established engineering principles and integration with existing grid infrastructure.The paper discusses the historical development,environmental benefits,and ongoing advancements in wave energy technologies,emphasizing the increasing feasibility and scalability of wave energy as a renewable source.Through a comprehensive analysis,this review provides insights into the current state and future prospects of electrical generators in wave energy conversion,underscoring their potential to significantly reduce reliance on fossil fuels and mitigate environmental impacts.
基金This study was supported by State Grid Corporation headquarters technology project(4000-202399368A-2-2-ZB).
文摘To address the excessive complexity of monthly scheduling and the impact of uncertain net load on the chargeable energy of storage,a reduced time-period monthly scheduling model for thermal generators and energy storage,incorporating daily minimum chargeable energy constraints,was developed.Firstly,considering the variations in the frequency of unit start-ups and shutdowns under different levels of net load fluctuation,a method was proposed to reduce decision time periods for unit start-up and shut-down operations.This approach,based on the characteristics of net load fluctuations,minimizes the decision variables of units,thereby simplifying the monthly schedulingmodel.Secondly,the relationship between energy storage charging and discharging power,net load,and the total maximum/minimum output of units was analyzed.Based on this,daily minimum chargeable energy constraints were established to ensure the energy storage system meets charging requirements under extreme net load scenarios.Finally,taking into account the operational costs of thermal generators and energy storage,load loss costs,and operational constraints,the reduced time-period monthly schedulingmodel was constructed.Case studies demonstrate that the proposedmethod effectively generates economical monthly operation plans for thermal generators and energy storage,significantly reduces model solution time,and satisfies the charging requirements of energy storage under extreme net load conditions.
文摘背景全科医生的培养和发展始终是医学界关注的焦点,而各国对全科医生的培训模式和方法存在显著的差异。目的总结并揭示我国全科医生培养的热点、趋势以及挑战,同时对比国外做法,为我国全科医生的未来发展提供借鉴和指导。方法采用文献计量学的方法,以CiteSpace 6.1.R Advanced软件为工具,国内研究分析基于中国知网(CNKI),国外研究分析选取Web of Science核心数据库(WOSCC),对2013—2023年国内外全科医生培养的文献进行筛选与定量化分析,并归纳总结。结果我国全科医生教育的研究数量逐年增长;我国研究机构以首都医科大学全科医学与继续教育学院发文量最多,但各机构间的合作不紧密;国外主要发文国家为英国和澳大利亚;我国全科医生培养研究偏向于教育方法改革和服务方向优化,而同期国外全科医生培养的研究侧重于人工智能技术的应用和对精神心理疾病的关注。结论我国全科医生培养的研究活动增长显著,集中在教育方法改革和服务方向优化,但各研究机构间需加强合作。对比国外研究模式,我国需要更多地引入新兴技术(如人工智能),并提升对精神心理疾病的关注度,以促进全科医生培养的深度和广度发展。
