未来大数据环境下的配用电通信网虚拟网络架构及应用

根据智能配电网的通信需求,本文提出了基于无线 Mesh 网和电力线通信网的智能配电网通信框架。在此框架的基础上,设计了一个遗传算法和启发式算法,为不同类型的业务分别建立虚拟网络并将其映射到异构的物理网络中,通过增加传输分集来保证实时业务的可靠性。通过仿真,验证两种映射算法在保证实时业务可靠性的基础上,使尽力而为型业务的吞吐率达到最大化。     

Analysis of low power wireless links in smart grid environments

Recently, wireless sensor networks (WSNs) have been used in various smart grid applications, including remote power system monitoring and control, power fraud detection, wireless automatic metering, fault diagnostics, demand response, outage detection, overhead transmission line monitoring, load control, and distribution automation. However, harsh smart grid environment propagation characteristics cause great challenges in the reliability of WSN communications in smart grid applications. To this end, the analysis of wireless link reliability and channel characterizations can help network designers to foresee the performance of the deployed WSN for specific smart grid propagation environments, and guide the network engineers to make design decisions for the channel modulation, encoding schemes, output power, and frequency band. This paper presents a detailed analysis of low power wireless link reliability in different smart grid environments, such as 500 kV outdoor substation environment, indoor main power control room, and underground network transformer vaults. Specifically, the proposed analysis aims to evaluate the impact of different sensor radio parameters, such as modulation, encoding, transmission power, packet size, as well as the channel propagation characteristics of different smart grid propagation environments on the performance of the deployed sensor network in smart grid. Overall, the main objective of this paper is to help network designers quantifying the impact of the smart grid propagation environment and sensor radio characteristics on low power wireless link reliability in harsh smart grid environments.     

A reliable QoS-aware routing scheme for neighbor area network in smart grid

A reliable bi-directional communication network is one of the key factors in smart grid (SG) to meet application requirements and improve energy efficiency. As a promising communication infrastructure, wireless mesh network (WMN) can provide high speed and cost-effect communication for SG. However, challenges remain to maintain high reliability and quality of service (QoS) when applying WMNs to SG. In this paper, we first propose a hybrid wireless mesh protocol (HWMP) based neighbor area network (NAN) QoS-aware routing scheme, named HWMP-NQ, to meet the QoS requirements by applying an integrated routing metric to route decision with effective link condition probing and queue optimization. To further improve the reliability of the proposed HWMP-NQ, we present a multi-gateway backup routing scheme along with a routing reliability correction factor to mitigate the impact of routing oscillations. Finally, we evaluate the performances of the proposed schemes on NS3 simulator. Extensive simulations demonstrate that HWMP-NQ can distinguish different applications and satisfy the QoS requirements respectively, and also improve the average packet delivery ratio and throughput with a reduced routing overhead, even with a high failure rate of mesh nodes.     

Performance evaluations of ZigBee in different smart grid environments

Recently, ZigBee Smart Energy profile has been developed for various smart grid applications, such as automatic metering, demand response, load control, power fraud detection, fault diagnostics, and distribution automation. In this paper, the performance of ZigBee has been evaluated in terms of network throughput, end-to-end delay, energy consumption, and packet delivery ratio in different smart grid environments, including an indoor power control room, an outdoor 500 kV substation environment, and an underground network transformer vaults. Overall, our performance evaluations show that the ZigBee is ideal to use for low-power and low-data rate smart grid applications not having very high reliability requirements and real-time deadlines.     

试论网络安全访问的规划与建设

随着电网的不断发展,无线网络通信技术得到了广泛的发展,很多先进的网络系统在智能电网建设中得到了充分运用,如移动办公系统、智能变电站无线巡检系统、电子围栏系统等都是智能电网网络规划的重点。本文针对智能电网无线局域网的规划与建设相关问题加以分析。     

Secure and robust multipath routings for advanced metering infrastructure

A Smart Grid is the modernization of the electricity grid using communication technology with the prime goals of reducing energy consumption as well as cost increasing reliability and creating new services for all participants. It comprises key components such as the Advanced Metering Infrastructure (AMI), which includes Neighborhood area network (NAN). When multi-hopping is considered in wireless communication, especially in WiFi and ZigBee, the range of the communication can be extended to communicate with the gateway collector in AMI network. Wireless mesh AMI network may have smart meters, a NAN gateway, and fixed as well as mobile repeaters. Though many techniques have been developed to secure on-demand routing protocols in wireless multi-hop ad-hoc networks, these protocols have shortcomings. In this paper, we propose two robust and secure multipath routing protocols for wireless mesh AMI networks. We have analyzed their robustness to various attacks. The simulation results show that the proposed protocols are better than existing secure routing protocols.     

The role of communication systems in smart grids: Architectures,technical solutions and research challenges

The purpose of this survey is to present a critical overview of smart grid concepts, with a special focus on the role that communication, networking and middleware technologies will have in the transformation of existing electric power systems into smart grids. First of all we elaborate on the key technological, economical and societal drivers for the development of smart grids. By adopting a data-centric perspective we present a conceptual model of communication systems for smart grids, and we identify functional components, technologies, network topologies and communication services that are needed to support smart grid communications. Then, we introduce the fundamental research challenges in this field including communication reliability and timeliness, QoS support, data management services, and autonomic behaviors. Finally, we discuss the main solutions proposed in the literature for each of them, and we identify possible future research directions.     

Secure communication mechanism for ubiquitous Smart grid infrastructure

Smart grid and advanced metering infrastructure (AMI) technologies have recently been the focus of rapid advancement and significant investment by many utilities and other service providers. For proper Smart grid deployment, smart energy home area network (HAN) must deploy smart meter along with other utility HAN devices and customer HAN devices. Energy service interface (ESI) is deployed as a HAN gateway which can provide two-way communications between HAN devices and utilities or service providers. However, in order to meet the envisioned functional, reliability, and scalability requirements of the Smart grid, cyber security must no longer be neglected. Thus, the development of a comprehensive security mechanism for AMI network is predominantly essential. A remote access to HAN devices may be required for either the customer that using his ubiquitous mobile device at the remote site or maintenance personals (either from utilities or service providers) those using handheld devices, which must be done securely. In this paper, we propose a security mechanism for remote access to HAN networks which is comprised of a lightweight and effective ECC-based entity authentication mechanism and ECC-based digital signature scheme. ECC-based entity authentication mechanism allows ESI as a gatekeeper to monitor the authentication process between two communicating entities. With a modified ECC-based digital signature scheme, secure data transfer between mobile devices and HAN devices has occurred. We have conducted security analysis, efficiency analysis as well as formal verification of the proposed mechanism.     

智能电网中家域网安全数据汇聚与调度方法研究

智能电网中通信网络的安全是实施智能电网的一个重要环节。用户信息的隐私保护是智能电网安全服务的一个主要任务。智能电网中用户信息隐私保护主要围绕智能电表数据的机密性和匿名性展开。本文以家域网作为智能电网通信网络的一个基本数据汇聚与调度单元,提出了一种安全的网内数据汇聚与调度方法,从而保证了智能家居设备的用电信息的机密性和匿名性。采用NS-2对本文提出的网内方法进行了仿真研究。仿真结果表明,本文提出的网内数据汇聚与调度方法与传统方法相比具有较高的实用性。     

Using genetic algorithms to design mesh networks

Designs for mesh communication networks must meet conflicting, interdependent requirements. This sets the stage for a complex problem with a solution that targets optimal topological connections, routing, and link capacity assignments. These assignments must minimize cost while satisfying traffic requirements and keeping network delays within permissible values. Since such a problem is NP-complete, developers must use heuristic techniques to handle the complexity and solve practical problems with a modest number of nodes. One heuristic technique, genetic algorithms, appears to be ideal to handle the design of mesh networks with capability of handling discrete values, multiobjective functions, and multiconstraint problems. Existing applications of genetic algorithms to this problem, however, have only optimized the network topology. They ignore the difficult subproblems of routing and capacity assignment, a crucial determiner of network quality and cost. This article presents a total solution to mesh network design using a genetic algorithm approach. The application is a 10-city network that links Hong Kong and nine other cities in China. The development demonstrates that this method can be used for networks of reasonable size with realistic topology and traffic requirements     

Cognitive maritime wireless mesh/ad hoc networks

Cognitive maritime wireless mesh/ad hoc networks are proposed in this paper, for the purpose to provide high-speed and low-cost communications for the current maritime users by incorporating the licensed but unused frequency bands opportunistically. Compared to other technologies, this scheme offers advantages of plenty of available bandwidth, easy installation, easy coverage extension, and high resilience. Nodes design requirements, possibly available frequency bands, regulation requirements, operation standards, and maritime communication challenges of the proposed networks are introduced and analyzed. A cognition-enhanced mesh medium access control (MAC) protocol for the operation of the proposed cognitive maritime mesh/ad hoc networks is presented, as well as a routing protocol and a switching antenna design that are capable of meeting the maritime challenges. Simulation results show that a higher detection probability and a longer sensing interval are both helpful to achieve better network performance, especially in case of high sea state. The operators need to find balance among cost, network performance, and protection of incumbents in the operation of the networks.     

QoS vs. energy: A traffic-aware topology management scheme for green heterogeneous networks

Increasing environmental awareness combined with the high energy prices has driven the network operators to reduce their carbon dioxide footprint by adopting energy efficient green methods. In this paper, we aim to save energy by both switching base stations on/off and adaptively adjusting their transmission power according to the present traffic conditions for heterogenous wireless cellular networks. We formulate a novel linear programming model for the Traffic-Aware Topology Management (TAM) problem to find the best possible topology which minimizes the overall power consumption of the network while satisfying a certain Quality of Service level in Wideband Code Division Multiple Access packet-switched cellular networks. Although the optimization tools provide the optimum solutions, it is not possible to handle large instances due to the space and computational complexity. Hence, we propose a Green TAM Algorithm to solve the large-scale realistic instances of the formulated problem and compare our results with the results of two previously proposed methods, a greedy heuristic and a commercial optimization tool. We show that the proposed TAM scheme helps to maintain an energy-aware network and saves significant amount of energy by adjusting the network topology to the current traffic conditions adaptively.     

Rematch: a highly reliable scheduling algorithm on heterogeneous wireless mesh network

In highly dynamic and heterogeneous wireless mesh networks (WMN), link quality will seriously affect network performance. Two challenges hinder us from achieving a highly efficient WMN. One is the channel dynamics. As in real network deployment, channel qualities are changing over time, which would seriously affect network bandwidth and reliability. Existing works are limited to the assumption that link quality values are fixed, and optimal scheduling algorithms are working on the fixed values, which would inevitably suffer from the link quality dynamics. Another challenge is the channel diversity. In single channel wireless networks, channel assignment and scheduling are NP\mathcal{NP} -hard. And in multichannel wireless networks, it could be even harder for higher throughput and efficient scheduling. In this study, we firstly characterize the stochastic behavior on wireless communications in a Markov process, which is based on statistical methodology. Secondly, on exploiting the stochastic behavior on wireless channels, we propose a stochastic programming model in achieving maximized network utilization. Considering the NP\mathcal{NP} -hardness, we propose a heuristic solution for it. The key idea in the proposed algorithm is a two-stage matching process named “Rematch.” Indeed, our solution to the stochastic network scheduling is a cross-layer approach. Also, we have proved that it is 2-approximate to the optimal result. Moreover, extensive simulations have been done, showing the efficiency of “Rematch” in highly dynamic and distributed wireless mesh networks.     

Communication network requirements for major smart grid applications in HAN,NAN and WAN

Since the introduction of the smart grid, accelerated deployment of various smart grid technologies and applications have been experienced. This allows the traditional power grid to become more reliable, resilient, and efficient. Despite such a widespread deployment, it is still not clear which communication technology solutions are the best fit to support grid applications. This is because different smart grid applications have different network requirements – in terms of data payloads, sampling rates, latency and reliability. Based on a variety of smart grid use cases and selected standards, this paper compiles information about different communication network requirements for different smart grid applications, ranging from those used in a Home Area Network (HAN), Neighborhood Area Network (NAN) and Wide-Area Network (WAN). Communication technologies used to support implementation of selected smart grid projects are also discussed. This paper is expected to serve as a comprehensive database of technology requirements and best practices for use by communication engineers when designing a smart grid network.     

基于WSNs和电力载波的教室智能节能系统设计

为了解决无线通信方式在教室控制网络中易受干扰和教室电器能源浪费问题,提出了一种基于无线传感器网络(WSNs)和电力线载波通信技术相结合的智慧教室电器节能设计方案.在总结了智慧教室控制系统研究现状、主要技术难点和挑战的基础上,着重阐述了智慧教室的控制网络拓扑结构和工作流程,详细分析了电力载波智能收发器的内部结构.此外,还实现了一种基于智能照明控制算法的智慧教室控制系统的原型.实验结果表明,该系统能够降低数据包的丢失率,相比普通LED照明系统能耗节省至少40％,并且运行可靠.     

浅谈智能变电站

智能电网已成为当今世界电力系统发展革新的最新动向,同时被认为是21世纪电力系统的发展趋势和重大科技创新。而智能变电站是智能电网建设的重要组成部分,是坚强智能电网的重要基础和支撑,所以世界各国在智能化变电站建设中都提出了不同的设计方案和构想,本文将对智能变电站的特点及功能进行简要分析。     

Effects of population size for location-aware node placement in WMNs: evaluation by a genetic algorithm--based approach

Wireless mesh networks (WMNs) are cost-efficient networks that have the potential to serve as an infrastructure for advanced location-based services. Location service is a desired feature for WMNs to support location-oriented applications. WMNs are also interesting infrastructures for supporting ubiquitous multimedia Internet access for mobile or fixed mesh clients. In order to efficiently support such services and offering QoS, the optimized placement of mesh router nodes is very important. Indeed, such optimized mesh placement can support location service managed in the mesh and keep the rate of location updates low. This node location-based problem has been shown to be NP-hard and thus is unlikely to be solvable in reasonable amount of time. Therefore, heuristic methods, such as genetic algorithms (GAs), are used as resolution methods. In this paper, we deal with the effect of population size for location-aware node placement in WMNs. Our WMN-GA system uses GA to determine the positions of the mesh routers and mesh clients in the grid area. We used a location-aware node placement of mesh router in cells of considered grid area to maximize network connectivity and user coverage. We evaluate the performance of the proposed and implemented WMN-GA system for low and high density of clients considering different distributions and considering giant component and number of covered users parameters. The simulation results show that for low-density networks, with the increasing of population size, GA obtains better result. However, with the increase in the population size, the GA needs more computational time. The proposed system has better performance in dense networks like hot spots for Weibull distribution when the population size is big.     

An expert system for wide area network component configuration

Abstract: Many organizations today have an interest in communications networks, either as users of public networks or as operators of their own private networks. Thus, the management of communications networks has become an important issue in the communications industry. The network design task is fundamental to the whole notion of network management; however, with the rapid rate of change in network technology and the emergence of highly sophisticated network users, network design has become an increasingly complex problem.
The purpose of this paper is to describe a development effort which incorporates expert systems techniques to treat one aspect of the network design problem—the initial planning and design of a network prior to implementation. The research effort was concerned with developing an expert system for Amdahl Communications Products which could be used by sales engineers in designing wide area networks to meet specified customer requirements. The system treats both the topological design problem and the component configuration problem.     

兼容串行通信与以太网通信的微机保护通信系统研究

随着变电站自动化技术在电力系统中的逐步应用,势必要求变电站中各二次设备逐步实现网络化。微机继电保护装置作为变电站重要的二次设备,对其通信系统提出了很高的要求。本文根据微机保护通信系统的要求,设计了由以太网与串行通信相结合的通信系统,阐述了通信系统的硬件构成,完成了相关驱动程序与通信功能软件的编写。开发的通信系统对于提高电力系统综合自动化水平具有重要的现实意义。     

Data forwarding based on sensor device constraints in wireless multimedia sensor networks

A variety of data forwarding schemes have been proposed for wireless multimedia sensor networks where energy awareness and reliability are essential design issues. This paper proposes a data forwarding mechanism based on sensor device constraints in wireless multimedia sensor networks. A dynamic path cost function is defined considering the constraints and characteristics of wireless multimedia sensor networks. The cost function is applied to ZigBee mesh routing, and the performance of the proposed method is evaluated using a QualNet network simulator.