简述了CAN(Controller Area Network)总线的现状和由FPGA实现的优势,由此设计了一种基于FPGA(Field-Programmable Gate Array)的CAN总线控制器,研发了一套基于此控制器的变电站环境动力监控系统,实现了对影响变电站安全运行的因素的在...简述了CAN(Controller Area Network)总线的现状和由FPGA实现的优势,由此设计了一种基于FPGA(Field-Programmable Gate Array)的CAN总线控制器,研发了一套基于此控制器的变电站环境动力监控系统,实现了对影响变电站安全运行的因素的在线监测。重点论述了该系统的整体结构、功能以及硬件电路设计及软件实现。实践证明,该系统性能可靠,准确率高,具有较高的使用价值。展开更多
Embedded Ethernet technology has been utilized increasingly widely as the communication mode in the substation automation system(SAS).This paper introduces the current applying situation about embedded Ethernet in SAS...Embedded Ethernet technology has been utilized increasingly widely as the communication mode in the substation automation system(SAS).This paper introduces the current applying situation about embedded Ethernet in SAS First.After analyzing the protocol levels used in SAS based on embedded Ethernet and the differences between the TCP and UDP,UDP/IP is selected as the communication protocol between the station-level and bay-level devices for its real-time characteristic.Then a new kind of implementation of the embedded Ethernet is presented based on hardware protocol stack.The designed scheme can be implemented easily,reduce cost significantly and shorten developing cycle.展开更多
Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to com...Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to complement the electricity gap. In this paper,a new structure of megawatt-class PV system integrating battery at DC-bus (DC: direct current) is proposed to be used in hydro/PV hybrid power system,and 4 main designing considerations and several key equipments are discussed. In 2011,a 2 MWp PV station with the proposed structure was built up in Yushu,China. From stability analysis,the station shows a strong stability under load cut-in/off and solar irradiance's fluctuation.展开更多
With the increase of capacity and size of the hydro-generator unit, the spiral case becomes a more super-giant hydraulic structure with very high HD value, where H and D denote water head and maximum intake diameter o...With the increase of capacity and size of the hydro-generator unit, the spiral case becomes a more super-giant hydraulic structure with very high HD value, where H and D denote water head and maximum intake diameter of spiral case, respectively. Due to the induced lower stiffness by the more giant size and adverse operation conditions, dynamic performances of the powerhouse and the supporting structure for the giant units have become more important and attracted much attention. If the manner of steel spiral case embedded directly in concrete is adopted, on some locations of the concrete surrounding the spiral case, distributed and concentrated cracks will emerge due to high tensile stress. Although the concrete is reinforced well to control the maximum crack width, definitely these cracks will reduce the local and entire stiffness of the powerhouse. Under dynamic loads such as hydraulic forces including water pressure pulsation in flow passage acting on the structure, effect of the cracks on the dynamic characteristics of the local members and entire structure needs to be evaluated. However, research on this subject is few in hydroelectric engineering. In this paper, Three-Gorge Project was taken as an example to evaluate effect of such cracks on natural frequencies and the vibration responses of the powerhouse under hydraulic and earthquake forces in detail. Results show that cracks only reduce the local structural stiffness greatly but have little effect on the entire powerhouse especially the superstructure; vibrations of powerhouse with cracks in concrete surrounding the spiral case are still under the design limits. Results in this paper have been verified by practice of Three-Gorge Project.展开更多
This paper analyzes the meaning, structure, function and assessment methods of a nuclear power plant evaluation system, and the similarities and differences among various assessment methods. Based on this research an ...This paper analyzes the meaning, structure, function and assessment methods of a nuclear power plant evaluation system, and the similarities and differences among various assessment methods. Based on this research an integrated and detailed suggestion is proposed on how to establish and improve internal and external evaluation systems for Chinese NPPs. It includes： to prepare and implement the nuclear power plant operational management program, to build an integrated performance indicator system, to improve the present audit system and conduct the comprehensive evaluation system, to set up and implement the integrated corrective action system, to position precisely the status of operation assessment of nuclear power plants, to conduct the assessment aetivilies on constructing NPP, to initiate the specific assessment in some important areas, to establish industrv performance indicator system, to improve the assessment methods, to share the assessment results, to select, cultivate and certify the reviewers, and to enhance interuational communication and cooperation.展开更多
Units and components of the powerful power equipment are exposed to the big static and dynamic load. An example of such equipments is turbines hydraulic power plant and, especially, hydroelectric pumped storage power ...Units and components of the powerful power equipment are exposed to the big static and dynamic load. An example of such equipments is turbines hydraulic power plant and, especially, hydroelectric pumped storage power plant. Existing techniques of control of a vibrating condition do not consider： very wide frequency range of vibrating processes, difficult character of such processes in the form of the sum multiharmonic, random and close to shock processes. Such techniques usually do not consider intervals of start-up and stop, and also work on transitive modes when loadings on a construction are maximum. Available techniques of an estimation of admissible level of vibrating influence and tests for vibration durability are not harmonized enough among themselves. Various known interpretations of communication of vibrating characteristics and durability estimations on mechanical pressure at broadband vibrating influence yield ambiguous result. On the basis of the analysis of the published information, we attempt to formulate the requirement to system of vibrating monitoring of the hydraulic turbine and power motor pumps. System should provide data acquisition and the analysis of the data on a vibrating condition taking into account accumulation of vibrating influences and long term of operation on the basis of estimation methods as low-cycle, and high-cycle （gigacycle） fatigue is made.展开更多
Due to recent legislative incentives and a general change in the public eye towards environmental and energy issues, a renewed interest in building nuclear power plants has taken place in the U.S. The Nuclear Regulato...Due to recent legislative incentives and a general change in the public eye towards environmental and energy issues, a renewed interest in building nuclear power plants has taken place in the U.S. The Nuclear Regulatory Commission has also recently given approvals to build four nuclear reactors in two southeast states, which further indicates the resurging interest in nuclear power in the U.S. Such approvals, however, do not specifically address the impact on having a constrained labor force when manufacturing and constructing multiple reactors. Key findings include the comparison of a constrained and unconstrained workforce on construction and manufacturing completion times, the identification of peak labor requirements based on different construction schedules, and the development of training estimates to ensure the workforce and industry are prepared for the new jobs being created. Results suggest that a shorter planned construction timeline is effective when the workforce is moderately constrained to unconstrained. However, with a severely-constrained starting workforce, a longer construction timeline is preferred. For multiple reactor plans, spreading out the construction start dates outperforms all other construction start date schedules. In particular, heavily compressed start dates could effectively kill a resurgent nuclear industry, especially if workforce expansion is not pursued simultaneously.展开更多
文摘简述了CAN(Controller Area Network)总线的现状和由FPGA实现的优势,由此设计了一种基于FPGA(Field-Programmable Gate Array)的CAN总线控制器,研发了一套基于此控制器的变电站环境动力监控系统,实现了对影响变电站安全运行的因素的在线监测。重点论述了该系统的整体结构、功能以及硬件电路设计及软件实现。实践证明,该系统性能可靠,准确率高,具有较高的使用价值。
文摘Embedded Ethernet technology has been utilized increasingly widely as the communication mode in the substation automation system(SAS).This paper introduces the current applying situation about embedded Ethernet in SAS First.After analyzing the protocol levels used in SAS based on embedded Ethernet and the differences between the TCP and UDP,UDP/IP is selected as the communication protocol between the station-level and bay-level devices for its real-time characteristic.Then a new kind of implementation of the embedded Ethernet is presented based on hardware protocol stack.The designed scheme can be implemented easily,reduce cost significantly and shorten developing cycle.
基金Chinese Academy of Science (No.KGCX2- YW- 366)Ministry of Science and Technology(No. 2011AA05A106)
文摘Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to complement the electricity gap. In this paper,a new structure of megawatt-class PV system integrating battery at DC-bus (DC: direct current) is proposed to be used in hydro/PV hybrid power system,and 4 main designing considerations and several key equipments are discussed. In 2011,a 2 MWp PV station with the proposed structure was built up in Yushu,China. From stability analysis,the station shows a strong stability under load cut-in/off and solar irradiance's fluctuation.
基金National Natural Science Foundation of China (No.50679009)Foundations for Young Teachers in Dalian University of Technology(No.893219)
文摘With the increase of capacity and size of the hydro-generator unit, the spiral case becomes a more super-giant hydraulic structure with very high HD value, where H and D denote water head and maximum intake diameter of spiral case, respectively. Due to the induced lower stiffness by the more giant size and adverse operation conditions, dynamic performances of the powerhouse and the supporting structure for the giant units have become more important and attracted much attention. If the manner of steel spiral case embedded directly in concrete is adopted, on some locations of the concrete surrounding the spiral case, distributed and concentrated cracks will emerge due to high tensile stress. Although the concrete is reinforced well to control the maximum crack width, definitely these cracks will reduce the local and entire stiffness of the powerhouse. Under dynamic loads such as hydraulic forces including water pressure pulsation in flow passage acting on the structure, effect of the cracks on the dynamic characteristics of the local members and entire structure needs to be evaluated. However, research on this subject is few in hydroelectric engineering. In this paper, Three-Gorge Project was taken as an example to evaluate effect of such cracks on natural frequencies and the vibration responses of the powerhouse under hydraulic and earthquake forces in detail. Results show that cracks only reduce the local structural stiffness greatly but have little effect on the entire powerhouse especially the superstructure; vibrations of powerhouse with cracks in concrete surrounding the spiral case are still under the design limits. Results in this paper have been verified by practice of Three-Gorge Project.
文摘This paper analyzes the meaning, structure, function and assessment methods of a nuclear power plant evaluation system, and the similarities and differences among various assessment methods. Based on this research an integrated and detailed suggestion is proposed on how to establish and improve internal and external evaluation systems for Chinese NPPs. It includes： to prepare and implement the nuclear power plant operational management program, to build an integrated performance indicator system, to improve the present audit system and conduct the comprehensive evaluation system, to set up and implement the integrated corrective action system, to position precisely the status of operation assessment of nuclear power plants, to conduct the assessment aetivilies on constructing NPP, to initiate the specific assessment in some important areas, to establish industrv performance indicator system, to improve the assessment methods, to share the assessment results, to select, cultivate and certify the reviewers, and to enhance interuational communication and cooperation.
文摘Units and components of the powerful power equipment are exposed to the big static and dynamic load. An example of such equipments is turbines hydraulic power plant and, especially, hydroelectric pumped storage power plant. Existing techniques of control of a vibrating condition do not consider： very wide frequency range of vibrating processes, difficult character of such processes in the form of the sum multiharmonic, random and close to shock processes. Such techniques usually do not consider intervals of start-up and stop, and also work on transitive modes when loadings on a construction are maximum. Available techniques of an estimation of admissible level of vibrating influence and tests for vibration durability are not harmonized enough among themselves. Various known interpretations of communication of vibrating characteristics and durability estimations on mechanical pressure at broadband vibrating influence yield ambiguous result. On the basis of the analysis of the published information, we attempt to formulate the requirement to system of vibrating monitoring of the hydraulic turbine and power motor pumps. System should provide data acquisition and the analysis of the data on a vibrating condition taking into account accumulation of vibrating influences and long term of operation on the basis of estimation methods as low-cycle, and high-cycle （gigacycle） fatigue is made.
文摘Due to recent legislative incentives and a general change in the public eye towards environmental and energy issues, a renewed interest in building nuclear power plants has taken place in the U.S. The Nuclear Regulatory Commission has also recently given approvals to build four nuclear reactors in two southeast states, which further indicates the resurging interest in nuclear power in the U.S. Such approvals, however, do not specifically address the impact on having a constrained labor force when manufacturing and constructing multiple reactors. Key findings include the comparison of a constrained and unconstrained workforce on construction and manufacturing completion times, the identification of peak labor requirements based on different construction schedules, and the development of training estimates to ensure the workforce and industry are prepared for the new jobs being created. Results suggest that a shorter planned construction timeline is effective when the workforce is moderately constrained to unconstrained. However, with a severely-constrained starting workforce, a longer construction timeline is preferred. For multiple reactor plans, spreading out the construction start dates outperforms all other construction start date schedules. In particular, heavily compressed start dates could effectively kill a resurgent nuclear industry, especially if workforce expansion is not pursued simultaneously.
