Neutral beam injection is one of the main plasma heating methods in nuclear fusion devices. In order to support the scientific study of the Experimental Advanced Superconducting Tokamak （EAST）, a megawatt-level high...Neutral beam injection is one of the main plasma heating methods in nuclear fusion devices. In order to support the scientific study of the Experimental Advanced Superconducting Tokamak （EAST）, a megawatt-level high current ion source is designed and manufactured in the ASIPP, and the progress and preliminary test results will be presented in this paper.展开更多
Modeling and simulation have emerged as an indispensable approach to create numerical experiment platforms and study engineering systems.However,the increasingly complicated systems that engineers face today dramatica...Modeling and simulation have emerged as an indispensable approach to create numerical experiment platforms and study engineering systems.However,the increasingly complicated systems that engineers face today dramatically challenge state-of-the-art modeling and simulation approaches.Such complicated systems,which are composed of not only continuous states but also discrete events,and which contain complex dynamics across multiple timescales,are defined as generalized hybrid systems(GHSs)in this paper.As a representative GHS,megawatt power electronics(MPE)systems have been largely integrated into the modern power grid,but MPE simulation remains a bottleneck due to its unacceptable time cost and poor convergence.To address this challenge,this paper proposes the numerical convex lens approach to achieve state-discretized modeling and simulation of GHSs.This approach transforms conventional time-discretized passive simulations designed for pure-continuous systems into state-discretized selective simulations designed for GHSs.When this approach was applied to a largescale MPE-based renewable energy system,a 1000-fold increase in simulation speed was achieved,in comparison with existing software.Furthermore,the proposed approach uniquely enables the switching transient simulation of a largescale megawatt system with high accuracy,compared with experimental results,and with no convergence concerns.The numerical convex lens approach leads to the highly efficient simulation of intricate GHSs across multiple timescales,and thus significantly extends engineers’capability to study systems with numerical experiments.展开更多
The gyrotron is one of the most promising high-power millimeter-wave sources for electron cyclotron resonance heating（ECRH） in controlled thermal nuclear fusion experiments.In this paper,the design of a high-frequen...The gyrotron is one of the most promising high-power millimeter-wave sources for electron cyclotron resonance heating（ECRH） in controlled thermal nuclear fusion experiments.In this paper,the design of a high-frequency interaction cavity of a 1 MW/140 GHz gyrotron is described in detail.The cavity is designed by using eigen mode analysis and radio frequency（RF） behavior calculation.Rounded transitions at the input and output tapers are designed for reducing mode conversion.With the obtained cavity structure,non-linear self-consistent equations are adopted to calculate its output power and efficiency.A particle-in-cell（PIC） method is used to simulate the beam-wave interaction process for obtaining the resonant frequency and output power of the cavity.The PIC simulation results match considerably well with the results obtained by the non-linear self-consistent calculation.The cavity is currently under construction and will be integrated with other components for overall testing.展开更多
Synchronous output of one beam line＇s two megawatt hot cathode bucket ion sources is required when Neutral Beam Injector （NBI） works on the Experimental Advanced Supercon- ducting Tokamak （EAST）. Neutral Beam Inj...Synchronous output of one beam line＇s two megawatt hot cathode bucket ion sources is required when Neutral Beam Injector （NBI） works on the Experimental Advanced Supercon- ducting Tokamak （EAST）. Neutral Beam Injector Control System （NBICS） realizes synchronous output and asynchronous output of two ion sources with network communication and hardware triggers. And the synchronous time can be set by operator. In synchronous mode, two megawatt hot cathode bucket ion sources can produce neutral beams at any relative time with higher energy than two sources＇ asynchronous output. Two megawatt hot cathode bucket ion sources＇ synchronous output makes an important contribution to NBI system of 4-8 MW with 10-100 s pulse length and provides more and better parameters for EAST physical experiments.展开更多
为研究兆瓦级高效紧凑型核动力系统的运行特性,使用自主开发的热管堆瞬态分析程序TAPIRS(Transient Analysis code for heat Pipe and AMTEC power conversion space Reactor power System)和超临界二氧化碳布雷顿循环的瞬态分析程序SCT...为研究兆瓦级高效紧凑型核动力系统的运行特性,使用自主开发的热管堆瞬态分析程序TAPIRS(Transient Analysis code for heat Pipe and AMTEC power conversion space Reactor power System)和超临界二氧化碳布雷顿循环的瞬态分析程序SCTRAN/CO_(2)(Super Critical reactors Transient Analysis code/Carbon Dioxide)的耦合程序对其反应性、负荷、冷却水温度和流量等扰动进行了开环动态响应分析,并据此进行了控制系统设计。在此基础上,对线性变负荷、阶梯式变负荷以及甩负荷这三种变负荷运行工况进行了计算分析。结果表明:该核动力系统的转速对扰动的变化较为敏感,需要加以控制;低负荷下旁通会使压缩机流量上升,需对压缩机流量加以控制;系统在控制方案下能以6%FP(Full Power)·min^(−1)的速度实现0%~100%的负荷变动,且可以在任意负荷水平下运行;甩负荷下系统的波动时间变长,但是仍可达到新的稳态进行工作,且各参数处于安全范围内。本研究可为新型核动力系统的概念设计提供参考。展开更多
1 Background The offshore wind resources of China are widely distributed and have large regional differences.The Yellow Sea and Bohai Sea areas,which account for 60%of the developable sea area,have an annual average w...1 Background The offshore wind resources of China are widely distributed and have large regional differences.The Yellow Sea and Bohai Sea areas,which account for 60%of the developable sea area,have an annual average wind speed of less than 7.5 m/s(Xu et al.,2013).According to the current level of offshore wind power transportation,construction,and operation and maintenance,the profit balance point of 5.0 MW offshore wind turbines is 3000 h/year(Zheng,2017).However,in the Yellow Sea and Bohai Sea areas,even if the world’s best offshore wind turbines at that time are used,their full power generation hours can only reach approximately 2900 h/year.This phenomenon is on the verge of profitability or loss,resulting in a large number of sea areas,especially the Bohai Sea area,with no development value.Therefore,developing offshore wind turbines with strong power generation capacity and low cost,which is suitable for the sea areas in China,is urgently needed.Thus,the H1715.0 MW offshore wind turbine project is introduced.展开更多
基金supported by National Natural Science Foundation of China (Nos.10875146,11075183)the Knowledge Innovation Program of the Chinese Academy of Sciences (study of the physical characteristic of arc power feedback control for the high current ion source)
文摘Neutral beam injection is one of the main plasma heating methods in nuclear fusion devices. In order to support the scientific study of the Experimental Advanced Superconducting Tokamak （EAST）, a megawatt-level high current ion source is designed and manufactured in the ASIPP, and the progress and preliminary test results will be presented in this paper.
基金the Major Program of National Natural Science Foundation of China(51490683).
文摘Modeling and simulation have emerged as an indispensable approach to create numerical experiment platforms and study engineering systems.However,the increasingly complicated systems that engineers face today dramatically challenge state-of-the-art modeling and simulation approaches.Such complicated systems,which are composed of not only continuous states but also discrete events,and which contain complex dynamics across multiple timescales,are defined as generalized hybrid systems(GHSs)in this paper.As a representative GHS,megawatt power electronics(MPE)systems have been largely integrated into the modern power grid,but MPE simulation remains a bottleneck due to its unacceptable time cost and poor convergence.To address this challenge,this paper proposes the numerical convex lens approach to achieve state-discretized modeling and simulation of GHSs.This approach transforms conventional time-discretized passive simulations designed for pure-continuous systems into state-discretized selective simulations designed for GHSs.When this approach was applied to a largescale MPE-based renewable energy system,a 1000-fold increase in simulation speed was achieved,in comparison with existing software.Furthermore,the proposed approach uniquely enables the switching transient simulation of a largescale megawatt system with high accuracy,compared with experimental results,and with no convergence concerns.The numerical convex lens approach leads to the highly efficient simulation of intricate GHSs across multiple timescales,and thus significantly extends engineers’capability to study systems with numerical experiments.
基金supported by International S&T Cooperation Program of China(No.2011DFA63190)China Postdoctoral Science Foundation(No.2014M552334)
文摘The gyrotron is one of the most promising high-power millimeter-wave sources for electron cyclotron resonance heating（ECRH） in controlled thermal nuclear fusion experiments.In this paper,the design of a high-frequency interaction cavity of a 1 MW/140 GHz gyrotron is described in detail.The cavity is designed by using eigen mode analysis and radio frequency（RF） behavior calculation.Rounded transitions at the input and output tapers are designed for reducing mode conversion.With the obtained cavity structure,non-linear self-consistent equations are adopted to calculate its output power and efficiency.A particle-in-cell（PIC） method is used to simulate the beam-wave interaction process for obtaining the resonant frequency and output power of the cavity.The PIC simulation results match considerably well with the results obtained by the non-linear self-consistent calculation.The cavity is currently under construction and will be integrated with other components for overall testing.
文摘Synchronous output of one beam line＇s two megawatt hot cathode bucket ion sources is required when Neutral Beam Injector （NBI） works on the Experimental Advanced Supercon- ducting Tokamak （EAST）. Neutral Beam Injector Control System （NBICS） realizes synchronous output and asynchronous output of two ion sources with network communication and hardware triggers. And the synchronous time can be set by operator. In synchronous mode, two megawatt hot cathode bucket ion sources can produce neutral beams at any relative time with higher energy than two sources＇ asynchronous output. Two megawatt hot cathode bucket ion sources＇ synchronous output makes an important contribution to NBI system of 4-8 MW with 10-100 s pulse length and provides more and better parameters for EAST physical experiments.
文摘为研究兆瓦级高效紧凑型核动力系统的运行特性,使用自主开发的热管堆瞬态分析程序TAPIRS(Transient Analysis code for heat Pipe and AMTEC power conversion space Reactor power System)和超临界二氧化碳布雷顿循环的瞬态分析程序SCTRAN/CO_(2)(Super Critical reactors Transient Analysis code/Carbon Dioxide)的耦合程序对其反应性、负荷、冷却水温度和流量等扰动进行了开环动态响应分析,并据此进行了控制系统设计。在此基础上,对线性变负荷、阶梯式变负荷以及甩负荷这三种变负荷运行工况进行了计算分析。结果表明:该核动力系统的转速对扰动的变化较为敏感,需要加以控制;低负荷下旁通会使压缩机流量上升,需对压缩机流量加以控制;系统在控制方案下能以6%FP(Full Power)·min^(−1)的速度实现0%~100%的负荷变动,且可以在任意负荷水平下运行;甩负荷下系统的波动时间变长,但是仍可达到新的稳态进行工作,且各参数处于安全范围内。本研究可为新型核动力系统的概念设计提供参考。
文摘1 Background The offshore wind resources of China are widely distributed and have large regional differences.The Yellow Sea and Bohai Sea areas,which account for 60%of the developable sea area,have an annual average wind speed of less than 7.5 m/s(Xu et al.,2013).According to the current level of offshore wind power transportation,construction,and operation and maintenance,the profit balance point of 5.0 MW offshore wind turbines is 3000 h/year(Zheng,2017).However,in the Yellow Sea and Bohai Sea areas,even if the world’s best offshore wind turbines at that time are used,their full power generation hours can only reach approximately 2900 h/year.This phenomenon is on the verge of profitability or loss,resulting in a large number of sea areas,especially the Bohai Sea area,with no development value.Therefore,developing offshore wind turbines with strong power generation capacity and low cost,which is suitable for the sea areas in China,is urgently needed.Thus,the H1715.0 MW offshore wind turbine project is introduced.
