±800 k V侨乡换流站500 k V交流滤波器562、583小组断路器选相合闸功能投入后,出现无法在电压过零点进行准确合闸的问题。通过分析断路器选相合闸装置的功能原理和实际配置,进行了断路器机械性能和带电分合等试验,认为选相合闸装...±800 k V侨乡换流站500 k V交流滤波器562、583小组断路器选相合闸功能投入后,出现无法在电压过零点进行准确合闸的问题。通过分析断路器选相合闸装置的功能原理和实际配置,进行了断路器机械性能和带电分合等试验,认为选相合闸装置的电气合闸时间要短于机械合闸时间,选相合闸的定值整定应适当考虑预击穿时间,必须对断路器的机械特性、预击穿特性进行试验验证,才可以确定正确定值序列,同时保留合理裕度。在合理设置选相合闸控制定值后,最终实现交流滤波器在电压过零点准确合闸。展开更多
Multi-terminal direct current(MTDC)grids provide the possibility of meshed interconnections between regional power systems and various renewable energy resources to boost supply reliability and economy.The modular mul...Multi-terminal direct current(MTDC)grids provide the possibility of meshed interconnections between regional power systems and various renewable energy resources to boost supply reliability and economy.The modular multilevel converter(MMC)has become the basic building block for MTDC and DC grids due to its salient features,i.e.,modularity and scalability.Therefore,the MMC-based MTDC systems should be pervasively embedded into the present power system to improve system performance.However,several technical challenges hamper their practical applications and deployment,including modeling,control,and protection of the MMC-MTDC grids.This paper presents a comprehensive investigation and reference in modeling,control,and protection of the MMC-MTDC grids.A general overview of state-of-the-art modeling techniques of the MMC along with their performance in simulation analysis for MTDC applications is provided.A review of control strategies of the MMC-MTDC grids which provide AC system support is presented.State-of-the art protection techniques of the MMCMTDC systems are also investigated.Finally,the associated research challenges and trends are highlighted.展开更多
The success of the Internet is largely ascribable to the packet-switching scheme, which, however, also presents major challenges. Having identified three missing links in the current Internet architecture based on our...The success of the Internet is largely ascribable to the packet-switching scheme, which, however, also presents major challenges. Having identified three missing links in the current Internet architecture based on our long-term experiences of designing and operating large-scale backbones, we put forward a new, but incrementally deployable, network schemc address switching. The address switching has both the advantages of packet switching and circuit switching; it supplies the missing links in the current Internet architecture and can reform the Internet traffic. Our analysis, protocol design and ex- periments indicate that the address switching can greatly improve the quality of service （QoS）, security and routing scalability of today＇s Internet. So it can provide flexible, high-performance and ＂per-service＂ networking for the scientific research communities. Moreover, it can provide a fairer and more sustainable business model for the commodity Internet.展开更多
为提高电信网设备应对异常信令访问的检测能力,需对64K信令进行分析并处理。为了提高解析效率并满足近年来相关产品对自主可控越来越高的要求,设计了一种基于国产现场可编程门阵列(Field Programmable Gate Array, FPGA)的信令解析方案...为提高电信网设备应对异常信令访问的检测能力,需对64K信令进行分析并处理。为了提高解析效率并满足近年来相关产品对自主可控越来越高的要求,设计了一种基于国产现场可编程门阵列(Field Programmable Gate Array, FPGA)的信令解析方案,给出了方案的总体设计思路,并对FPGA实现的功能模块进行详细说明。对系统进行设计时,采用模块化参数化方法以及在关键环节添加状态参数,提高了可扩展性并可以对模块内部运行状态进行监控,最终实现了对信令高效且灵活的解析,主要器件等均为国产。经过测试,可以实现STM-1(STM-Synchronous Transfer Module-1)数据的接入、串并转换、HDLC(High-level Data Link Control)解帧等功能,完成32路64K信令的并发处理,模块运行状态可查可看,达到了预期的效果。以STM-1为例,基于现有功能的模块化设计,可以平滑地扩展到STM-4、STM-16的应用。展开更多
文摘±800 k V侨乡换流站500 k V交流滤波器562、583小组断路器选相合闸功能投入后,出现无法在电压过零点进行准确合闸的问题。通过分析断路器选相合闸装置的功能原理和实际配置,进行了断路器机械性能和带电分合等试验,认为选相合闸装置的电气合闸时间要短于机械合闸时间,选相合闸的定值整定应适当考虑预击穿时间,必须对断路器的机械特性、预击穿特性进行试验验证,才可以确定正确定值序列,同时保留合理裕度。在合理设置选相合闸控制定值后,最终实现交流滤波器在电压过零点准确合闸。
基金funded by SGCC Science and Technology Program under project Research on Electromagnetic Transient Simulation Technology for Large-scale MMC-HVDC Systems.
文摘Multi-terminal direct current(MTDC)grids provide the possibility of meshed interconnections between regional power systems and various renewable energy resources to boost supply reliability and economy.The modular multilevel converter(MMC)has become the basic building block for MTDC and DC grids due to its salient features,i.e.,modularity and scalability.Therefore,the MMC-based MTDC systems should be pervasively embedded into the present power system to improve system performance.However,several technical challenges hamper their practical applications and deployment,including modeling,control,and protection of the MMC-MTDC grids.This paper presents a comprehensive investigation and reference in modeling,control,and protection of the MMC-MTDC grids.A general overview of state-of-the-art modeling techniques of the MMC along with their performance in simulation analysis for MTDC applications is provided.A review of control strategies of the MMC-MTDC grids which provide AC system support is presented.State-of-the art protection techniques of the MMCMTDC systems are also investigated.Finally,the associated research challenges and trends are highlighted.
基金Supported by the China Next Generation Internet Project (Grant No. CNGI-04-13-2T)the National Basic Research Program of China(Grant No. 041710001)
文摘The success of the Internet is largely ascribable to the packet-switching scheme, which, however, also presents major challenges. Having identified three missing links in the current Internet architecture based on our long-term experiences of designing and operating large-scale backbones, we put forward a new, but incrementally deployable, network schemc address switching. The address switching has both the advantages of packet switching and circuit switching; it supplies the missing links in the current Internet architecture and can reform the Internet traffic. Our analysis, protocol design and ex- periments indicate that the address switching can greatly improve the quality of service （QoS）, security and routing scalability of today＇s Internet. So it can provide flexible, high-performance and ＂per-service＂ networking for the scientific research communities. Moreover, it can provide a fairer and more sustainable business model for the commodity Internet.
文摘为提高电信网设备应对异常信令访问的检测能力,需对64K信令进行分析并处理。为了提高解析效率并满足近年来相关产品对自主可控越来越高的要求,设计了一种基于国产现场可编程门阵列(Field Programmable Gate Array, FPGA)的信令解析方案,给出了方案的总体设计思路,并对FPGA实现的功能模块进行详细说明。对系统进行设计时,采用模块化参数化方法以及在关键环节添加状态参数,提高了可扩展性并可以对模块内部运行状态进行监控,最终实现了对信令高效且灵活的解析,主要器件等均为国产。经过测试,可以实现STM-1(STM-Synchronous Transfer Module-1)数据的接入、串并转换、HDLC(High-level Data Link Control)解帧等功能,完成32路64K信令的并发处理,模块运行状态可查可看,达到了预期的效果。以STM-1为例,基于现有功能的模块化设计,可以平滑地扩展到STM-4、STM-16的应用。
