多控制器体系结构是提高软件定义网络(Software Defined Networks,SDN)可扩展性和可靠性的必须条件。分层多控制器结构允许全局控制器处理罕见事件,例如本地控制器的路由事件。在控制器出现故障的情况下,多控制器结构需要故障转移机制,...多控制器体系结构是提高软件定义网络(Software Defined Networks,SDN)可扩展性和可靠性的必须条件。分层多控制器结构允许全局控制器处理罕见事件,例如本地控制器的路由事件。在控制器出现故障的情况下,多控制器结构需要故障转移机制,包括故障检测和恢复。而现有的控制器故障检测和恢复机制在本地控制器中执行,可能会降低本地控制器的性能。加之在控制器故障恢复中,现有机制没有考虑可用于减少流量建立时间的时变负载标准偏差度量。展开更多
目前,在含统一潮流控制器(unified power flow controller,UPFC)的电网静态安全分析中,UPFC的控制目标有功功率、无功功率通常采用典型运行数据进行离线分析,控制目标值由试探法确定,计算效率低且和实际运行工况存在一定的差异。为弥补...目前,在含统一潮流控制器(unified power flow controller,UPFC)的电网静态安全分析中,UPFC的控制目标有功功率、无功功率通常采用典型运行数据进行离线分析,控制目标值由试探法确定,计算效率低且和实际运行工况存在一定的差异。为弥补现有控制策略整定方法的不足,文中提出了采用潮流转移分布因子的UPFC控制值整定方法,当电网发生N-1故障时,基于直流潮流法定量计算控制目标值,通过UPFC的潮流控制功能消除线路N-1过载,控制策略可根据能量管理系统(energy management system,EMS)数据在线刷新,可为电网调度提供辅助决策。算例仿真验证了文中算法的有效性和实用性。展开更多
In order to improve the scalability and reliability of Software Defined Networking(SDN),many studies use multiple controllers to constitute logically centralized control plane to provide load balancing and fail over.I...In order to improve the scalability and reliability of Software Defined Networking(SDN),many studies use multiple controllers to constitute logically centralized control plane to provide load balancing and fail over.In this paper,we develop a flexible dormant multi-controller model based on the centralized multi-controller architecture.The dormant multi-controller model allows part of controllers to enter the dormant state under light traffic condition for saving system cost.Meanwhile,through queueing analysis,various performance measures of the system can be obtained.Moreover,we analyze the real traffic of China Education Network and use the results as the parameters of computer simulation and verify the effects of parameters on the system characteristics.Finally,a total expected cost function is established,and genetic algorithm is employed to find the optimal values of various parameters to minimize system cost for the deployment decision making.展开更多
文摘多控制器体系结构是提高软件定义网络(Software Defined Networks,SDN)可扩展性和可靠性的必须条件。分层多控制器结构允许全局控制器处理罕见事件,例如本地控制器的路由事件。在控制器出现故障的情况下,多控制器结构需要故障转移机制,包括故障检测和恢复。而现有的控制器故障检测和恢复机制在本地控制器中执行,可能会降低本地控制器的性能。加之在控制器故障恢复中,现有机制没有考虑可用于减少流量建立时间的时变负载标准偏差度量。
基金the National High-tech R&D Program ("863" Program) of China，the National Science Foundation of China，National Science & Technology Pillar Program of China，the National Science Foundation of China，the Post-Doctoral Funding of China，Tsinghua-Huawei joint research project
文摘In order to improve the scalability and reliability of Software Defined Networking(SDN),many studies use multiple controllers to constitute logically centralized control plane to provide load balancing and fail over.In this paper,we develop a flexible dormant multi-controller model based on the centralized multi-controller architecture.The dormant multi-controller model allows part of controllers to enter the dormant state under light traffic condition for saving system cost.Meanwhile,through queueing analysis,various performance measures of the system can be obtained.Moreover,we analyze the real traffic of China Education Network and use the results as the parameters of computer simulation and verify the effects of parameters on the system characteristics.Finally,a total expected cost function is established,and genetic algorithm is employed to find the optimal values of various parameters to minimize system cost for the deployment decision making.
