共查询到20条相似文献,搜索用时 15 毫秒
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针对孤岛微电网中无功功率分配、通讯延时等问题,文中提出了一种基于一致性算法的分层控制算法。各分布式电源在时钟周期下与相邻的分布式电源交换电压信息,通过本地电压一致性算法得到全网平均电压值,可随迭代周期更新电压状态值,以实现各分布式电源无功功率的精确分配。电压一致性算法中,本地节点与相邻节点存在通讯延时,由微电网系统的拓扑结构可得到相邻节点间最大通讯延时时间,并由PI算法动态补偿延时误差。在MATLAB/Simulink平台搭建孤岛型微电网仿真模型,实验结果证明了控制策略的有效性。 相似文献
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电力线通信在智能电网中起到了愈发重要的作用。除了传输信息以外,对电力线网络自身结构的感知也是电力线通信的重要功能之一。通过将电力线网络建模为一个树型网络,同时充分利用电力线通信“通过电网”的特性,恢复电力线网络拓扑结构的能力成为可能。利用电力线网络的信道模型,通过节点之间信号的收发实现了电力线网络拓扑结构的估计。先后利用了矩阵束方法和动态重建方法,仿真结果显示,两种方法可以高概率地正确恢复网络结构,并且高精度地对电力线网络拓扑结构的细节进行恢复。 相似文献
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A hybrid relay control mechanism for ribbon topology in low‐voltage power line communication networks
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The communication reliability and distance of the low‐voltage power line communication system are seriously affected by the channel interference and the time variant load impedance. Therefore, how to control the relay nodes to reduce the communication delay and improve the communication reliability is mainly considered in the design. A novel hybrid relay control mechanism (HRCM) that includes the static relay pre‐configuration and the dynamic relay selection is designed for the ribbon topology in the low‐voltage power line communication networks. In the ribbon topology, the initial configuration for the communication link is realized through the pre‐configure relay nodes, which guarantees that the concentrator can communicate with the furthest terminal node. During the normal operations, the dynamic relay node is selected according to the sequence number of the uplink or downlink data frame and the data discard strategy. With the relay node dynamical selected mechanism, the frame repeated transmission can be avoided and the communication delay is reduced. The actual test results show that the hybrid relay control mechanism can effectively extend the communication distance, improve the communication real‐time and the reliability of the low‐voltage power line communication. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Communicating with sensors has long been limited either to wired connections or to proprietary wireless communication protocols. Using a ubiquitous and inexpensive wireless communication technology to create Sensor Area Networks (SANs) will accelerate the extensive deployment of sensor technology. Bluetooth, an emerging, worldwide standard for inexpensive, local wireless communication is a viable choice for SANs because of its inherent support for some of the important requirements – low power, small form factor, low cost and sufficient communication range. In this paper we outline an approach, centered on the Bluetooth technology, to support a sensor network composed of fixed wireless sensors for health monitoring of highways, bridges and other civil infrastructures. We present a topology formation scheme that not only takes into account the traffic generated by different sensors but also the associated link strengths, buffer capacities and energy availability. The algorithm makes no particular assumptions as to the placement of nodes, and not all nodes need to be in radio proximity of each other. The output is a tree shaped scatternet rooted at the sensor hub (data logger) that is balanced in terms of traffic carried on each of the links. We also analyze the scheduling, routing and healing aspects of the resulting sensor-net topology. 相似文献
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Hidetoshi Takeshita Naoaki Yamanaka Satoru Okamoto Sho Shimizu Shan Gao 《Optical Switching and Networking》2012,9(3):264-270
An innovative energy-efficient network design algorithm and a tool to lower the network power consumption are proposed. The goal is an energy efficient network that carries its rated communication load while meeting the QoS requirements by using the minimum set of nodes and links. QoS metrics include hop limit, bandwidth limit reliability and stability. The proposed algorithm addresses the set-covered problem. To discover the optimum network configuration efficiently, we propose a network configuration generation algorithm that utilizes DAPDNA-2, a parallel data flow type reconfigurable processer. The processor automatically produces the node/link set in n-digit binary form where links are modeled as “1” for power on and “0” for power off; it also confirms that the QoS requirements are satisfied. Evaluation results show that DAPDNA-2 is 2-orders faster than the conventional sequential method running on a Pentium-4 processor. Prototype Gigabit Layer-2 switches having remote link power on/off and traffic monitoring functions are developed. Using these switches, we successfully demonstrate an energy efficient IP/Ethernet network. The evaluation results show that network power savings of up to 30% can be realized under the NFSNET topology model. The proposed algorithm and power efficient network architecture can be applied to realize the future green network. 相似文献
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我国"十二五"电网发展规划明确指出,要加快智能电网的建设,实现电力光纤入户。智能电网建设的关键技术之一是电力通信。目前,由于我国电力通信专用网呈现"骨干网强、接入网弱"、"高(电压)端强,低端弱"的态势,配电、用电环节的通信水平相对输电网而言差距较大,而智能配电和用电建设是智能电网用电环节的一个重要组成部分。因此,智能电网中的"最后一百米"显得尤为重要。伴随着光纤生产技术的发展,塑料光纤以其芯径大、柔韧性好、接续方便等特点,即将成为接入网的传输媒质。 相似文献
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Many network-reliability analysis techniques define and compute a variety of reliability measures. Most techniques assume that network connectivity is the only determining factor in network reliability; and merely analyze an existing network structure but do not provide any methodology for reliable design. This paper presents a heuristic design algorithm to enhance the reliability of existing communication networks by modifying their topology. This algorithm improves the reliability of the least reliable node (reliability is the probability that messages transmitted from a given node reach their destination). To use this algorithm on large networks, a reliability analysis method is developed which determines approximate network reliability values in linear-time when an upper bound is placed upon the in-degree of all network nodes. The heuristic network design algorithm uses this approximate reliability analysis technique to place additional links. The goal of this link placement is to improve the reliability of the least-reliable node. The placement of additional links is a function of both the traffic distribution and the connectivity of the network. This process continues until either a desired level of network reliability is achieved or a maximum number of additional links has been added. A unique feature of this design strategy is that it has quadratic time-complexity when the maximum in-degree of all network nodes is limited 相似文献
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该文主要研究了无线Ad hoc网络中节点失效的情况下,如何维护网络的连通性和拓扑的性能,并且尽可能地降低拓扑维护的开销。提出了基于最短路径树的拓扑维护算法。该算法在拓扑变化时首先触发失效节点的邻节点响应(即重新运行拓扑控制算法),在不增加额外通信开销的情况下,响应的节点根据相互发送的Hello分组来判断网络是否连通;如果不能确定网络是连通的,再触发失效节点的其它可达邻近节点响应。仿真研究表明,算法显著地减少了拓扑维护的开销,维护后的拓扑结构在功率有效性和功率扩展因子等方面也取得了好的性能。 相似文献
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针对无线网络链路可靠性差影响无线虚拟网络的分配这一问题,提出了一种基于链路可靠性的无线虚拟网络分配算法(WVNEA-LR)。该算法通过物理网络拓扑预处理和允许同一个虚拟请求中的多个虚拟节点映射到同一个物理节点上的方法,提高了Vn构建成功率和节约了物理链路资源。利用Q因子改善了因拓扑分配稀疏时Vn构建成功率低的问题。此外,WVNEA-LR的节点分配为链路分配作了准备,并通过选择可靠性高的承载路径保证了分配后的Vn具有高可靠性。仿真结果表明, WVNEA-LR获得较好的虚拟网络构建成功率、较高的收益成本比和资源利用率。 相似文献
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Reliability Evaluation of a Network with Delay 总被引:1,自引:0,他引:1
In a computer or communication network, the reliability and transfer-delay of communication are important measures of performance. This paper describes a method of evaluating the reliability of a network with delay. When network elements fail, delay is defined as the length of the shortest remaining path between two specified nodes. We find the occurrence probability of events that a central node can communicate with a group of terminal nodes so that a specified delay is not exceeded. The desired events are mutually exclusive and contain a tree. Our algorithm efficiently generates all the events by noting network topology. The paper includes the case of several central nodes. 相似文献
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Reliability optimization of computer-communication networks 总被引:1,自引:0,他引:1
The evaluation of the reliability of a given computer communication network is a NP-hard problem. Hence, the problem of assigning reliabilities to links of a fixed computer communication network topology to optimize the system reliability is also NP-hard. A heuristic method is developed to assign links to a given topology so that the system reliability of the network is near optimal. The method provides a way to assign reliability measures to the links of a network to increase overall reliability. It is based on the principle that the most reliable link should be assigned to the most vulnerable edge. The method computes an importance order for the edges of the network and uses the order to assign link reliabilities. If there are fewer than six links in a network, it can be shown that the method gives optimal assignment 相似文献
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分析了基于低功耗自适应分簇(LEACH)路由协议的无线传感网络(WSN)在不同拓扑形状下的生命周期,并改进了长方形拓扑形状的路由协议。进而针对WSN在某些场合能量有限、易受干扰和安全性差等缺点,在长方形区域中引入分布式光纤传感结构。将传感光纤铺设在环境复杂和外界电磁波干扰大的监测区域,从而提高整个传感网络的生命周期和可靠性。理论分析和仿真结果表明,改进的拓扑和协议在提高可靠性的同时,有效地延长了光WSN的生存时间,性能优于传统LEACH协议。 相似文献
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本文提出了求通信网络总可靠度的状态空间树法。它直接产生网络图的一个不交化树多层多项式,优点是计算量较小[计算时间复杂度为0(?),(?)为边数,n_1为叶数],所得表达式较短。在此基础上应用超图理论提出了求通信网络总可靠度的精确分解算法。用它进行网络图的m次分解,一台计算机所能计算的通信网络规模可以扩大m倍。 相似文献