Optimal Communication Network Research Articles

Towards Forming Optimal Communication Network for Effective Power System Restoration

Towards Forming Optimal Communication Network for Effective Power System Restoration

Optimization of Communication Network for Distributed Control of Wind Farm Equipped With Energy Storages

Consensus based distributed control schemes have been widely applied to different operation scenarios of wind farms (WFs). However, few studies concern the influences of WF communication network topology to the consensus control performances. This paper proposes an optimal design method of the WF communication network for the consensus based re/active power regulation control of the WF, in which each individual wind turbine (WT) is equipped with an energy storage (ES) unit. Firstly, the basic model of the WT equipped with ES is presented, and the consensus based control scheme of the power regulation is described. Secondly, the optimization model for the communication network is constructed, so as to speed up the convergence rate, improve the communication survivability and reduce the communication links in the control. Thirdly, this paper proposes a bi-level alternating direction method of multipliers (ADMM) based solving framework, which decomposes the optimization into sub-problems. Finally, the performances of the control using the designed optimal communication network are tested and compared with other networks in the control, and the results verify the superiority of the proposed method.

Optimal Communication Network Design of Microgrids Considering Cyber-Attacks and Time-Delays

Distributed secondary control stands out for its flexibility and expandability in microgrids (MGs) control, in where communication network plays a fundamental and critical role. The communication topology and link-weights have significant impact on the attack-resilience and dynamic performance of MGs, which should be appropriately designed. However, the joint optimization problem of communication topology and link-weights in the existing literature of consensus-based secondary voltage control of MGs is usually neglected. To bridge this gap, we propose a novel two-stage optimization approach for the communication network design, which jointly optimizes the topological structure to enhance the structural survivability and link weights to improve the dynamic performance (including the speed of convergence and robustness to time-delay). The first stage problem is formulated into a mixed-integer semi-define programming (MISDP) model based on convex relaxation technique, which is then converted equivalently into an integer quadratic programming (IQP) problem and then a MISDP feasibility problem to facilitate the solution. The second stage problem is formulated into a bi-objective SDP model to compromise between the convergence performance and robustness to time-delay. Simulations based on a microgrid with 10 distributed generation (DG) units under different scenarios are implemented to verify the effectiveness of the proposed method.

Internet of underwater things communication: Architecture, technologies, research challenges and future opportunities

Recently, the Internet of things (IoT) paradigm has proliferated all aspect of life. The improvements IoT has made in business and industry has raised the possibility of extending its use to underwater environments, which also impacts human life. Consequently, Internet of Underwater Things (IoUT) research is intensifying. As in IoT, to deploy a successful application in IoUT, an optimal communication network is required. However, underwater environments pose unique technical challenges for setting up such networks. The aim of these networks is to achieve optimal performance required for efficient and reliable transmission within IoUT. Communication is the lifeline of a network and involves the transmission of information along a medium or path. Thus, it is critical to understand the impact of underwater environment on IoUT communication. Overall, IoUT communication utilizes underwater and terrestrial equipment. We focus on underwater communication where the medium is water and information is transmitted as acoustic/sound signals. With respect to physical, Medium Access Control (MAC) and network layers, we investigate issues associated with designing optimal IoUT networks. The underwater ecosystem varies spatially with time so, knowledge of prevailing underwater regional profiles at any time is essential. Profiles enable the construction of necessary constraints that affect optimized performance of IoUT networks. We analyze the constraints imposed by different regional profiles of underwater ecosystem and their impact on optimal IoUT communication. These constraints affect performance goals required for successful IoUT network deployment. The analysis is useful for developing state-of-the-art IoUT communication strategies based on stochastic optimization models.

CONSTRUCTION OF TRANSPORT COMPANY’S INFORMATION INFRASTRUCTURE

The purpose of the article is to study the information aspects of the activities of a motor transport enterprise, to build a communication network within the enterprise, which seeks to fully satisfy the needs of society for the transportation of goods and passengers. Methodology. The study was carried out using graph theory - one of the major branches of discrete mathematics, which is widely used in solving economic and management problems. Using these methods, the minimum path in the information network is found. Results. The quality and timeliness of information coming in the forward and backward directions determines the quality of management of individual objects of the road transport system, as well as the possibility of its coordinated functioning in order to fully satisfy the needs of society for the transportation of goods and passengers. The article examines the introduction of information technologies in transport, which are used at all stages of receiving, storing, processing and transmitting information, should fully ensure the timeliness and high quality of information support when making managerial decisions at all levels of the transport system. The general principles of the construction and functioning of motor transport systems are analyzed through the prism of the information procedures implemented in them and the emerging information flows. It has been established that most of the total volume of information processed in a company can be information necessary for the management and control of logistics operations. Since the road transport system is geographically distributed, a modern specialist must master the methods of spatial analysis based on geoinformation technologies. The development of the information and communication infrastructure of a new transport company, which plans to carry out the transportation of goods by road, has been investigated. The company will provide services such as cargo transportation, freight forwarding services, cargo tracking, cargo insurance, settlement of cargo deliveries, cargo unloading and loading. For the optimal placement of the company's network, graph theory is used. An optimal communication network has been built, connecting various departments of the company, namely, the transportation department, the office, the accounting department, the economic planning department, the legal department, the mechanical department, the communications department, and the personnel department. The scientific novelty of the article is the use of the method for constructing an optimal communication network at a trucking company. The practical significance of the work is that this method can be used at any transport company that begins its activity to build communication links between any departments of the company. In this case, these connections will be optimal.

Cost-effective communication network planning considering performance of pinning-based secondary control in microgrids

Driven by the fact that the structural topology of the communication network has a significant effect on the dynamical performance of the related physical network, this paper addresses the communication network planning problem for islanded microgrids (MGs). The optimal communication topology with the lowest communication cost, which supports the desired performance of pinning-based distributed control is designed in the MG planning stage. To achieve that, firstly, pinning synchronization control (PSC) is developed to regulate the voltage and frequency at each distributed generator (DG) to the reference state. Then criteria of the algebraic connectivity of communication network to fulfill the convergence requirement of PSC protocols are derived analytically using spectral graph properties and Lyapunov theory. A communication network planning model is formulated as Mixed Integer Semidefinite Program (MISDP) by using Linear Matrix Inequalities (LMI) techniques. The convergence speed requirement of PSC, communication time delay and the importance of connections between DGs are considered as constraints. The optimal communication network with the lowest communication cost can be acquired and meanwhile the satisfactory dynamical performance of PSC protocols can be guaranteed. The case studies are designed to evaluate how the planning model can practically facilitate the pinning-based control in the islanded MG. The simulation results effectively verify that the dynamical control convergence can be improved under the properly designed communication network. The control performance of the proposed protocol is validated experimentally based on a two-DG MG prototype.

Distributed Economic Dispatch Scheme for Droop-Based Autonomous DC Microgrid

In this paper, a distributed economic dispatch scheme considering power limit is proposed to minimize the total active power generation cost in a droop-based autonomous direct current (DC) microgrid. The economical dispatch of the microgrid is realized through a fully distributed hierarchical control. In the tertiary level, an incremental cost consensus-based algorithm embedded into the economical regulator is utilized to search for the optimal solution. In the secondary level, the voltage regulator estimating the average voltage of the DC microgrid is used to generate the voltage correction item and eliminate the power and voltage oscillation caused by the deviation between different items. Then, the droop controller in the primary level receives the reference values from the upper level to ensure the output power converging to the optimum while recovering the average voltage of the system. Further, the dynamic model is established and the optimal communication network topology minimizing the impact of time delay on the voltage estimation is given in this paper. Finally, a low-voltage DC microgrid simulation platform containing different types of distributed generators is built, and the effectiveness of the proposed scheme and the performance of the optimal topology are verified.

Methods for multicriterial selection of optimal routes in communication networks

Traditionally, the problems of routing in communication networks are solved based on the scalar approach, which takes into consideration only one quality indicator. However, information transmission in communication networks is characterized by a totality of quality indicators. That is why to obtain the optimal solution to the problems of routing in a communication network, it is necessary to use the multicriterial approach. This determines the relevance of solving the problem of routing in communication networks considering the totality of quality indicators, which characterize the quality of information transmission. To solve this problem, this study used the methods of multicriterial optimization. The methods for discrete selection of a subset of Pareto-optimal variants of routing taking into consideration the totality of quality indicators were proposed. In this case, unconditionally worse options for routing are excluded and potentially possible values of the totality of quality indicators are ensured. It also suggests a possibility of multipath routing organization, which provides uniform loading of all communication lines. The practical features of application of the selected methods of multicriterial optimization for choosing optimal routes in communication networks taking into consideration the totality of quality indicators were explored. The advantages and constraints of the multicriterial approach to solving the problem of routing in communication networks were shown. The research results are useful for professionals who are engaged in planning and designing optimal communication networks.

An Intelligent Vehicle Control System for Enhancing Road Safety Using Optimal Visible Light Communication Network

Abstract A visible light communication (VLC) provides potential and effective communication paradigm due to the demand of high data-rate applications. VLC networks, consisting of multiple light emitting diodes (LEDs) and it provides the low-cost high data-rate transmission to multiple users simultaneously in indoor environments. VLC has been recently introduced as a secure directional data transmission in vehicle to vehicle to provide an intelligent vehicle control system. However, the performance of this system is mostly affected by the collision of data transmission between different users. In this paper, we introduce an optimal visible light communication (OVLC) network that allows vehicles which have provides collision aware data transmission to improve the chance of transmitting information successively according to the network condition. Firstly, the next forwarding node is selected by the chaotic fish swarm optimization (CFSO) algorithm with the help of vehicle information’s such as intensity of light, the distance and speed of neighboring vehicles. The second contribution is to illustrate the congestion control (CC) system for avoiding extra time due to the control packets exchange process. The optimal result is then forward to the source vehicle equipped device, which helps the driver to make a healthy to control vehicle and efficiently avoid or prevent road accidents under different circumstances. The results show that the proposed OVLC network performs very efficient than existing network in terms of quality metrics, such as throughput, delay, packet loss rate, energy consumption and fairness index.

A DC programming approach for solving multicast network design problems via the Nesterov smoothing technique

This paper continues our recent effort in applying continuous optimization techniques to study optimal multicast communication networks modeled as bilevel hierarchical clustering problems. Given a finite number of nodes, we consider two different models of multicast networks by identifying a certain number of nodes as cluster centers, and at the same time, locating a particular node that serves as a total center so as to minimize the total transportation cost throughout the network. The fact that the cluster centers and the total center have to be among the given nodes makes these problems discrete optimization problems. Our approach is to reformulate the discrete problems as continuous ones and to apply Nesterov's smoothing approximation techniques on the Minkowski gauges that are used as distance measures. This approach enables us to propose two implementable DCA-based algorithms for solving the problems. Numerical results and practical applications are provided to illustrate our approach.

Towards mesoscale analysis of inter-vehicle communications

Cooperative traffic systems renew much research interest with the rapid development of communication technologies. This paper considers a finite number of vehicles moving in a single lane from a mesoscale perspective and explores the spectral properties of such a cooperative system, in particular how the communication range and the coupling weights influence the eigenvalues of the global disturbance transition matrix (DTM), i.e., disturbance modes of the traffic system. Dynamics of these vehicles are described by a modified coupled-map car-following model under periodic boundaries with inter-vehicle communications. From a state-space approach, a system DTM is established from a global view and a closed-form solution of its eigenvalues is derived. Linear stability conditions are subsequently obtained. It is found that the eigenvalue distribution of system DTM is essentially dominated by the communication range and the coupling weights, but nearly independent of the system size. By analyzing the magnitudes of the dominant poles, the synchronization of the traffic system is enhanced if the weights of the vehicles within the communication range are more evenly distributed or the communication range is increased. Particularly, it is shown that the optimal communication network tends to be a mean-field network w.r.t. global synchronization, indicating that a communication network emphasizing uniform importance among vehicles within each vehicle’s communication range is helpful for improving the synchronizability. Finally, numerical simulations verify the results.

Risk assessment for the cascading failure of electric cyber‐physical system considering multiple information factors

A risk assessment approach for the cascading failure of electric cyber-physical system (ECPS) considering multiple information factors is proposed. First, considering hardware, software and personnel factors existing in the information system, the reliability model of the control function of the information system is established. Second, the reliability model of the physical component considering the control function of the information system is established. Finally, the risk assessment approach for the cascading failure of ECPS is introduced, and the probability of the cascading failure and the expected energy not supplied are used as the risk indices. Test results on an improved RTS-79 system show the effectiveness and significance of the method for choosing the optimal power communication network topology and the measures to reduce the risk.

Enhancing synchronization stability in a multi-area power grid.

Maintaining a synchronous state of generators is of central importance to the normal operation of power grids, in which many networks are generally interconnected. In order to understand the condition under which the stability can be optimized, it is important to relate network stability with feedback control strategies as well as network structure. Here, we present a stability analysis on a multi-area power grid by relating it with several control strategies and topological design of network structure. We clarify the minimal feedback gain in the self-feedback control, and build the optimal communication network for the local and global control strategies. Finally, we consider relationship between the interconnection pattern and the synchronization stability; by optimizing the network interlinks, the obtained network shows better synchronization stability than the original network does, in particular, at a high power demand. Our analysis shows that interlinks between spatially distant nodes will improve the synchronization stability. The results seem unfeasible to be implemented in real systems but provide a potential guide for the design of stable power systems.

Optimal topological design of power communication networks using genetic algorithm

An electric power supply is the backbone of development in advanced as well as in developing economies. An integral part of ensuring a secure power supply system is a power communication system. Due to the high and sustained performance requirements of power communication systems, electric companies prefer to construct their own communication networks privately rather than relying solely on a public communication system. The focus of this paper is on the optimal topological design of a power communication network. Based on advanced optimization models in public communication networks, and taking into account the specific Quality of Service, as demanded by various applications, such as protection, SCADA, voice, etc., an optimization model (PC/ISO) has been developed. The PC/ISO requires tedious numerical processing. Hence, a Genetic Algorithm (GA) is proposed to solve the optimization problem. In order to demonstrate the application of the proposed model for a power system communication network design and in order to evaluate GA solver results, a case study on designing the optimal communication network topology of one of the Iranian Regional Electric Companies has been conducted. The results suggest that the PC/ISO model and its GA solver are entirely viable and offer a simple, accurate, and cost effective solution.

An Efficient Constructive Approximation Approach to Design A K-Connected Network Topology

The purpose of designing an optimal and fault tolerant communication network is to achieve a precise performance without any disruption at a minimal cost. A network is said to be k- link fault tolerant (nodes are assumed reliable) if it is able to maintain connectivity in the presence of failures in any set of arbitrarily k links simultaneously. Communication network topology design cost depends on the number of the links used to design a desired fault tolerant communication network and is equal to the sum of the cost of all required links. The main objective of a fault tolerant network design approach is therefore to select the minimum number of low cost links while satisfying the pre-specified fault tolerance/connectivity. It has also been proved that designing a minimum cost communication network topology under the connectivity constraint is a NP hard problem. Several constructive approximation algorithms have be enproposed to design a fault tolerant network topology. But the existing algorithms are not so much effective for selecting minimum number of low cost links to design a computer network topology. In this paper, we have proposed an efficient constructive approximation approach for designing a k – connected network which is survivable in the presence of k-1 links failures in the network. The design cost and number of links required to design such network using proposed approach is less than the existing approaches. Effectiveness of proposed approach is also checked using various examples.

TCP/IP Based Intelligent Load Management System in Micro-Grids Network Using MATLAB/Simulink

Computerized power management system with fast and optimal communication network overcomes all major dicrepencies of undue or inadequate load relief that were present in old conventional systems. This paper presents the basic perception and methodology of modern and true intelligent load management scheme in micro grids topology by employing TCP/IP protocol for fast and intelligent switching. The network understudy performs load management and power distribution intelligently in a unified network. Generated power is efficiently distributed among local loads through fast communication system of server in the form of source and clients in the form of loads through TCP/IP. The efficient use of information between server and clients enables to astutely control the load management in a power system of micro grids system. The processing time of above stated system comes out to be 10ms faster than others which ensure very less delay as compared to conventional methods. The Micro Grids system operating through TCP/IP control has been implemented in MATLAB/Simulink and results have been verified.

Intelligent Load Shedding Using TCP/IP for Smart Grids

Computerized power management system with fast and optimal communication network overcomes all major discrepancies of undue or inadequate load relief that were present in old conventional systems. This paper presents the basic perception and methodology of modern and true intelligent load shedding scheme in micro grids topology by employing TCP/IP protocol for fast and intelligent switching. The network understudy performs load management and power distribution intelligently in a unified network. Generated power is efficiently distributed among local loads through fast communication system of server in the form of source and clients in the form of loads through TCP/IP. The efficient use of information between server and clients enables to astutely control the load shedding in a power system of micro grids system. The processing time of above stated system comes out to be 10 ms faster than others which ensure very less delay as compared to conventional methods. The Micro Grids system operating through TCP/IP control has been implemented in MATLAB/SIMULINK and results have been verified.

An independent set approach for the communication network of the GPS III system

In this article, we describe an algorithm to find the optimal communication network for the new GPS III satellite system. Finding a possible network will be translated to a maximum clique problem and an efficient algorithm for finding all maximum cliques under these special circumstances is described.

A Fully Distributed Lagrangean Solution for a Peer-to-Peer Overlay Network Design Problem

Peer-to-peer (P2P) computing already accounts for a large part of the traffic on the Internet, and it is likely to become as ubiquitous as current client/server architectures in next generation information systems. This paper addresses a central problem of P2P systems: the design of an optimal overlay communication network for a set of processes on the Internet. Such a network defines membership to the P2P group and allows for members to disseminate information within the group. The problem, named the membership overlay problem (MOP), can be formulated as a dynamic optimization problem where classical combinatorial optimization techniques must face the further challenge of time-varying input data. This paper proposes an innovative, fully distributed, and asynchronous subgradient optimization algorithm for the Lagrangean relaxation of the MOP, which can run online in fully decentralized P2P systems, and integrates it with a distributed heuristic that can achieve sound hot-start states for fast response to varying network structures.

Detailed Analysis of Team Movement and Communication Affecting Team Performance in the America's Army Game

Abstract : We conducted the second data analysis with a new game log record dataset and focused on what the optimal team structure is in terms of communication and movement. We utilized regression analyses and correspondence analyses to make the optimal network, and we identified several important features of optimal networks from those analyses. Furthermore we coded Network Fitter and used it to make a computer program figure out the most effective team organization. From the fitting result, we could obtain five optimal movement networks and five optimal communication networks. Among them, we found out that a dense movement network with two sub graphs and a long-chain shaped communication network would make casualty lower without damaging the deadliness of a team. After identifying the optimal movement networks and communication networks, we applied the findings from the analyses to the real world and made three recommendations on training squad level unit, constructing effective TTP, and configuring an optimal squad unit.