On the Exploitation of Admittance Measurements for Wired Network Topology Derivation

The knowledge of the topology of a wired network is often of fundamental importance. For instance, in the context of Power Line Communications (PLC) networks it is helpful to implement data routing strategies, while in power distribution networks and Smart Micro Grids (SMG) it is required for grid monitoring and for power flow management. In this paper, we use the transmission line theory to shed new light and to show how the topological properties of a wired network can be found exploiting admittance measurements at the nodes. An analytic proof is reported to show that the derivation of the topology can be done in complex networks under certain assumptions. We also analyze the effect of the network background noise on admittance measurements. In this respect, we propose a topology derivation algorithm that works in the presence of noise. We finally analyze the performance of the algorithm using values that are typical of power line distribution networks.Comment: A version of this manuscript has been submitted to the IEEE Transactions on Instrumentation and Measurement for possible publication. The paper consists of 8 pages, 11 figures, 1 tabl

Optimisation of Mobile Communication Networks - OMCO NET

The mini conference “Optimisation of Mobile Communication Networks” focuses on advanced methods for search and optimisation applied to wireless communication networks. It is sponsored by Research & Enterprise Fund Southampton Solent University. The conference strives to widen knowledge on advanced search methods capable of optimisation of wireless communications networks. The aim is to provide a forum for exchange of recent knowledge, new ideas and trends in this progressive and challenging area. The conference will popularise new successful approaches on resolving hard tasks such as minimisation of transmit power, cooperative and optimal routing

An ant colony optimization approach for maximizing the lifetime of heterogeneous wireless sensor networks

Maximizing the lifetime of wireless sensor networks (WSNs) is a challenging problem. Although some methods exist to address the problem in homogeneous WSNs, research on this problem in heterogeneous WSNs have progressed at a slow pace. Inspired by the promising performance of ant colony optimization (ACO) to solve combinatorial problems, this paper proposes an ACO-based approach that can maximize the lifetime of heterogeneous WSNs. The methodology is based on finding the maximum number of disjoint connected covers that satisfy both sensing coverage and network connectivity. A construction graph is designed with each vertex denoting the assignment of a device in a subset. Based on pheromone and heuristic information, the ants seek an optimal path on the construction graph to maximize the number of connected covers. The pheromone serves as a metaphor for the search experiences in building connected covers. The heuristic information is used to reflect the desirability of device assignments. A local search procedure is designed to further improve the search efficiency. The proposed approach has been applied to a variety of heterogeneous WSNs. The results show that the approach is effective and efficient in finding high-quality solutions for maximizing the lifetime of heterogeneous WSNs

Cyber Physical System Security — DoS Attacks on Synchrophasor Networks in the Smart Grid

With the rapid increase of network-enabled sensors, switches, and relays, cyber-physical system security in the smart grid has become important. The smart grid operation demands reliable communication. Existing encryption technologies ensures the authenticity of delivered messages. However, commonly applied technologies are not able to prevent the delay or drop of smart grid communication messages. In this dissertation, the author focuses on the network security vulnerabilities in synchrophasor network and their mitigation methods. Side-channel vulnerabilities of the synchrophasor network are identified. Synchrophasor network is one of the most important technologies in the smart grid transmission system. Experiments presented in this dissertation shows that a DoS attack that exploits the side-channel vulnerability against the synchrophasor network can lead to the power system in stability. Side-channel analysis extracts information by observing implementation artifacts without knowing the actual meaning of the information. Synchrophasor network consist of Phasor Measurement Units (PMUs) use synchrophasor protocol to transmit measurement data. Two side-channels are discovered in the synchrophasor protocol. Side-channel analysis based Denial of Service (DoS) attacks differentiate the source of multiple PMU data streams within an encrypted tunnel and only drop selected PMU data streams. Simulations on a power system shows that, without any countermeasure, a power system can be subverted after an attack. Then, mitigation methods from both the network and power grid perspectives are carried out. From the perspective of network security study, side-channel analysis, and protocol transformation has the potential to assist the PMU communication to evade attacks lead with protocol identifications. From the perspective of power grid control study, to mitigate PMU DoS attacks, Cellular Computational Network (CCN) prediction of PMU data is studied and used to implement a Virtual Synchrophasor Network (VSN), which learns and mimics the behaviors of an objective power grid. The data from VSN is used by the Automatic Generation Controllers (AGCs) when the PMU packets are disrupted by DoS attacks. Real-time experimental results show the CCN based VSN effectively inferred the missing data and mitigated the negative impacts of DoS attacks. In this study, industry-standard hardware PMUs and Real-Time Digital Power System Simulator (RTDS) are used to build experimental environments that are as close to actual production as possible for this research. The above-mentioned attack and mitigation methods are also tested on the Internet. Man-In-The-Middle (MITM) attack of PMU traffic is performed with Border Gateway Protocol (BGP) hijacking. A side-channel analysis based MITM attack detection method is also investigated. A game theory analysis is performed to give a broade

Electronically-switched Directional Antennas for Low-power Wireless Networks: A Prototype-driven Evaluation

We study the benefits of electronically-switched directional antennas in low-power wireless networks. This antenna technology may improve energy efficiency by increasing the communication range and by alleviating contention in directions other than the destination, but in principle requires a dedicated network stack. Unlike most existing works, we start by characterizing a real-world antenna prototype, and apply this to an existing low-power wireless stack, which we adapt with minimal changes. Our results show that: i) the combination of a low-cost directional antenna and a conventional network stack already brings significant performance improvements, e.g., nearly halving the radio-on time per delivered packet; ii) the margin of improvement available to alternative clean-slate protocol designs is similarly large and concentrated in the control rather than the data plane; iii) by artificially modifying our antenna's link-layer model, we can point at further potential benefits opened by different antenna designs

Vulnerability analysis of satellite-based synchronized smart grids monitoring systems

The large-scale deployment of wide-area monitoring systems could play a strategic role in supporting the evolution of traditional power systems toward smarter and self-healing grids. The correct operation of these synchronized monitoring systems requires a common and accurate timing reference usually provided by a satellite-based global positioning system. Although these satellites signals provide timing accuracy that easily exceeds the needs of the power industry, they are extremely vulnerable to radio frequency interference. Consequently, a comprehensive analysis aimed at identifying their potential vulnerabilities is of paramount importance for correct and safe wide-area monitoring system operation. Armed with such a vision, this article presents and discusses the results of an experimental analysis aimed at characterizing the vulnerability of global positioning system based wide-area monitoring systems to external interferences. The article outlines the potential strategies that could be adopted to protect global positioning system receivers from external cyber-attacks and proposes decentralized defense strategies based on self-organizing sensor networks aimed at assuring correct time synchronization in the presence of external attacks

Forecasting Recharging Demand to Integrate Electric Vehicle Fleets in Smart Grids

Electric vehicle fleets and smart grids are two growing technologies. These technologies provided new possibilities to reduce pollution and increase energy efficiency. In this sense, electric vehicles are used as mobile loads in the power grid. A distributed charging prioritization methodology is proposed in this paper. The solution is based on the concept of virtual power plants and the usage of evolutionary computation algorithms. Additionally, the comparison of several evolutionary algorithms, genetic algorithm, genetic algorithm with evolution control, particle swarm optimization, and hybrid solution are shown in order to evaluate the proposed architecture. The proposed solution is presented to prevent the overload of the power grid