Two heuristic methods are proposed to find an effective and fast solution in modern power distribution networks.For solving the service restoration problem in distribution networks,switch selection indices based on an...Two heuristic methods are proposed to find an effective and fast solution in modern power distribution networks.For solving the service restoration problem in distribution networks,switch selection indices based on an analytic approach and a practicable heuristic graph-based method are given.The formulation of the problem includes four different objective functions:1)maximizing the total load restored;2)minimizing the number of switching operations;3)maximizing the top priority restored load;4)minimizing load shedding.A suitable evaluation of switch indices is used for all candidate tie switches(TSs)in the network to find the best solution and decrease the number of switching operations.A new graph-based approach is utilized for finding the best sectionalizes switch(SS)and minimizing the voltage drop.The accuracy and the validity of the approach are tested in two standard electrical distribution networks.The results of the approach are used for IEEE 69-bus and IEEE 119-bus test case.展开更多
The current power grid is facing many challenges that it was not designed or engineered to handle which range from congestions and major blackouts to the overwhelming increase in demand and security concerns. The curr...The current power grid is facing many challenges that it was not designed or engineered to handle which range from congestions and major blackouts to the overwhelming increase in demand and security concerns. The current electric grid was established before the 1960’s. It is believed that the electric grid is the most complex and gigantic machine ever made in human history;it consists of wires, cables, towers, transformers and circuit breakers installed together in outdated manner. During the 60’s, computers and sensors were used to monitor and slightly control the grid;however, fifty years later these sensors are considered less than ideal. Presented here is a review of the smart grid communication network in terms of configuration, bandwidth and latency requirements as well as the technology used. We simulate the access layer of the smart grid net-work and show that no single available communication technology can be used for all layers of the smart grid;thus, different technologies for different layers are needed. A new protocol for optimizing the smart grid is recommended.展开更多
在软件定义网络(Software Defined Networking,SDN)中,控制层很容易受到分布式拒绝服务(Distributed Denial of Service,DDoS)攻击的威胁。攻击者通过恶意请求或数据流等方式,向SDN控制器发送大量请求,从而使控制器资源耗尽,导致控制器...在软件定义网络(Software Defined Networking,SDN)中,控制层很容易受到分布式拒绝服务(Distributed Denial of Service,DDoS)攻击的威胁。攻击者通过恶意请求或数据流等方式,向SDN控制器发送大量请求,从而使控制器资源耗尽,导致控制器不能正常工作。因此,防范和处理控制层DDoS攻击是SDN安全的关键。该文提出一种基于区块链与排队理论的DDoS攻击检测防御机制,该防御机制结合区块链技术,设计了一种新的SDN架构模型,该模型对SDN控制层重新进行构造,在SDN控制层加入容量监控模块、安全模块及区块链模块。容量监控模块基于排队理论,计算进入控制器数据包队列的长度阈值,当队列内数据包数目连续2次超过阈值或控制器规则表容量达到70%容量触发报警,安全模块用于触发报警后在设置报警的数据包进行DDoS特征匹配,如果被确定为异常数据则将数据包摘要信息上传至区块链,利用智能合约共享异常数据包信息摘要,既能够防止过多的信息记录在区块链造成系统负载,又能够使SDN网络信息达成共识。对该攻击检测防御机制进行仿真实验,选出了效果最优参数,实验结果表明,与同类型系统相比,该机制对异常数据流的检测率及正常数据流的误报率均有所提升。展开更多
为了实现基于4G宽带技术的配电自动化系统DAS的通信服务子系统,采用4G LTE技术实现配电馈线终端FTU的网络接入.针对用户需求,在其与移动运营商之间物理专线的基础之上,利用运营商提供的集团客户VPDN业务,采用L2TP over IPSec技术实现了...为了实现基于4G宽带技术的配电自动化系统DAS的通信服务子系统,采用4G LTE技术实现配电馈线终端FTU的网络接入.针对用户需求,在其与移动运营商之间物理专线的基础之上,利用运营商提供的集团客户VPDN业务,采用L2TP over IPSec技术实现了DAS与FTU之间的VPN网络通道,达到配电自动化信息安全传输的目的.基于所构建的通信网络,进行DAS通信服务器软件的设计,实现了DAS系统数据采集和输出控制的通信功能.实验结果表明,所构思实现的通信子系统达到了通信功能和网络安全的指标要求.展开更多
文摘Two heuristic methods are proposed to find an effective and fast solution in modern power distribution networks.For solving the service restoration problem in distribution networks,switch selection indices based on an analytic approach and a practicable heuristic graph-based method are given.The formulation of the problem includes four different objective functions:1)maximizing the total load restored;2)minimizing the number of switching operations;3)maximizing the top priority restored load;4)minimizing load shedding.A suitable evaluation of switch indices is used for all candidate tie switches(TSs)in the network to find the best solution and decrease the number of switching operations.A new graph-based approach is utilized for finding the best sectionalizes switch(SS)and minimizing the voltage drop.The accuracy and the validity of the approach are tested in two standard electrical distribution networks.The results of the approach are used for IEEE 69-bus and IEEE 119-bus test case.
文摘The current power grid is facing many challenges that it was not designed or engineered to handle which range from congestions and major blackouts to the overwhelming increase in demand and security concerns. The current electric grid was established before the 1960’s. It is believed that the electric grid is the most complex and gigantic machine ever made in human history;it consists of wires, cables, towers, transformers and circuit breakers installed together in outdated manner. During the 60’s, computers and sensors were used to monitor and slightly control the grid;however, fifty years later these sensors are considered less than ideal. Presented here is a review of the smart grid communication network in terms of configuration, bandwidth and latency requirements as well as the technology used. We simulate the access layer of the smart grid net-work and show that no single available communication technology can be used for all layers of the smart grid;thus, different technologies for different layers are needed. A new protocol for optimizing the smart grid is recommended.
文摘在软件定义网络(Software Defined Networking,SDN)中,控制层很容易受到分布式拒绝服务(Distributed Denial of Service,DDoS)攻击的威胁。攻击者通过恶意请求或数据流等方式,向SDN控制器发送大量请求,从而使控制器资源耗尽,导致控制器不能正常工作。因此,防范和处理控制层DDoS攻击是SDN安全的关键。该文提出一种基于区块链与排队理论的DDoS攻击检测防御机制,该防御机制结合区块链技术,设计了一种新的SDN架构模型,该模型对SDN控制层重新进行构造,在SDN控制层加入容量监控模块、安全模块及区块链模块。容量监控模块基于排队理论,计算进入控制器数据包队列的长度阈值,当队列内数据包数目连续2次超过阈值或控制器规则表容量达到70%容量触发报警,安全模块用于触发报警后在设置报警的数据包进行DDoS特征匹配,如果被确定为异常数据则将数据包摘要信息上传至区块链,利用智能合约共享异常数据包信息摘要,既能够防止过多的信息记录在区块链造成系统负载,又能够使SDN网络信息达成共识。对该攻击检测防御机制进行仿真实验,选出了效果最优参数,实验结果表明,与同类型系统相比,该机制对异常数据流的检测率及正常数据流的误报率均有所提升。
文摘为了实现基于4G宽带技术的配电自动化系统DAS的通信服务子系统,采用4G LTE技术实现配电馈线终端FTU的网络接入.针对用户需求,在其与移动运营商之间物理专线的基础之上,利用运营商提供的集团客户VPDN业务,采用L2TP over IPSec技术实现了DAS与FTU之间的VPN网络通道,达到配电自动化信息安全传输的目的.基于所构建的通信网络,进行DAS通信服务器软件的设计,实现了DAS系统数据采集和输出控制的通信功能.实验结果表明,所构思实现的通信子系统达到了通信功能和网络安全的指标要求.
