Distributed Communication Architecture Research Articles

Enhanced AC/DC optimal power flow via nested distributed optimization for AC/VSC-MTDC hybrid power systems

The deployment of voltage source converters (VSC) to facilitate flexible interconnections between the AC grid, renewable energy system (RES) and Multi-terminal DC (MTDC) grid is on the rise. However, significant challenges exist in exploiting coordinated operations for such AC/VSC-MTDC hybrid power systems. One of the most critical issues is how to achieve the optimal operation of such wide-area systems involving several power entities with as minimal communication burden as possible. To address this issue, an enhanced AC/DC optimal power flow (OPF) is specifically proposed. Firstly, a mixed-integer convex AC/DC OPF model is explicitly formulated to describe the optimal operation of such hybrid power systems. Subsequently, a nested distributed optimization method with double iteration loops is developed to offer optimal system-wide decision-making through a more “thorough” distributed communication architecture. In the outer iteration, the original AC/DC OPF problem is decomposed into several slave problems (SPs) associated with systems (including the AC grid and RESs) and one master problem (MP) associated with the integrated VSC-MTDC grid. Generalized Benders decomposition (GBD) serves to solve the master and slave problems iteratively. Techniques such as multi-cut generation and asynchronous updating are utilized to upgrade the GBD performance of computation efficiency and address communication delays. In the inner iteration, the master problem is continuously decomposed into multiple sub-MPs associated with individual VSCs. The alternating direction method of multipliers (ADMM) is employed to solve these sub-MPs iteratively. Proximal terms and heuristic approaches are embedded to enable parallel computation and handling of integer variables. Numerical experiment results finally validate the effectiveness of the proposed enhanced AC/DC OPF. The constructed AC/DC OPF model exhibits acceptable accuracy in terms of power flow calculation, and the developed nested distributed optimization method showcases decent convergence rate and solution optimality performances.

I-Sare. The Future Grid.

This paper presents a real implementation of hierarchical control scheme for a smart grid equipped with voltage source converters, attached to renewable and conventional energy generators and storage systems based on ultracapacitors, flywheel and batteries, which is able to assume the demand of domestic, commercial, industrial and electric vehicle demanding current loads up to 400 kw in islanded mode or connected to the main grid. The hierarchical control used is implemented in the central control system and in each of the converters connected to the intelligent grid, in order to distribute the control over all the elements involved in the generation of energy. For this purpose it is used a distributed communication architecture based on EPICS to manage all the information generated. This micro grid, called i-Sare, was developed during the 2012 and beginning of 2013, and will be operational in Donostia (Gipuzkoa) at the end of 2013. In this paper real test results are presented to demonstrate the effectiveness of the control and the communication architecture used in iSare.

Resource allocation model for cloud-fog-based smart grid

This paper investigates the allocation model, the flexibility, and the scalability of fully distributed communication architectures for metering systems in smart grids. Smart metering infrastructure aggregates data from Smart Meters (SMs) and sends the collected data to the fog or the cloud data centres to be stored and analysed. The system needs to be scalable and reliable and to respond to increased demand with minimal cost. The problem is to find the optimal distribution of application data among devices, data centres or clouds. The need for support computing at marginal resources, which can be hosted within the building itself or shared within the construction of the complex, has become important over recent years. The resource allocation model is presented to optimize the cost of the resources in the communications and relevance parts of computing (the data processing cost). The fog helps cloud computing connectivity on the edge network. This paper explains how calculation/analysis can be performed closer to the data collection site to complement the analysis that would be undertaken at the data centre. Results for a range of typical scenarios are presented to show the effectiveness of the proposed method.

Standardization of the Distributed Ledger Technology cybersecurity stack for power and energy applications

The global trend toward integration of distributed energy resources is opening doors to advanced, complex, and distributed marketplaces. Such advanced ecosystems, where utility-owned and non utility-owned assets can contribute toward grid operations, generally require distributed communication and grid architectures. We posit the potential of using Distributed Ledger Technologies (DLTs) in supporting such applications, although their full potential has not been fully used, for example in designing long-term scalable solutions in operational technology applications. This is partly due to the lack of standardization across and between different DLTs, as well as other supporting building blocks (e.g., communication protocols). This paper attempts to address this gap by proposing a DLT cybersecurity stack specifically designed for researchers, DLT technology developers, and end users (such as utilities). The DLT cybersecurity stack has been notionally mapped to related cybersecurity components, namely the Open Systems Interconnection (OSI) model, the Transmission Control Protocol/Internet Protocol (TCP/IP) suite, and existing Smart Grid architecture frameworks. In addition, the paper discusses several cybersecurity implications, and demonstrates the potential uses of the DLT cybersecurity stack through multiple power and energy use cases. It is important to note that the stack can be also applied to the DLT use cases that are outside the power and energy domain. This work was performed by the Cybersecurity Task Force under the IEEE P2418.5 Blockchain for Energy Standard working group that part of the IEEE Power and Energy Society’s Smart Buildings, Loads, and Customer Systems (SBLC) technical committee.

Investigation of Distributed Cooperative Control for DC Microgrids in Different Communication Medium

This paper is based on a detailed study of cooperative secondary control strategy for accurate load sharing in DC microgrids in different communication medium. Since accuracy in DC voltage regulation and load sharing can’t be achieved simultaneously in a non-negligible impedance network, an adaptive droop has been proposed to address this issue to a significant extent via a secondary controller. A fixed primary droop controller along with a conventional secondary controller generally introduces a loading mismatch between converters while accomplishing voltage regulation at load bus. To combat this issue, an adaptive droop is proposed to improve power sharing along with a tertiary update used for fine-tuning. Since a distributed controller collect information from its neighbors, its performance is highly influenced by the communication medium and its characteristics, such as latency, failure rate, etc. Hence, the efficacy of the proposed distributed communication architecture is tested in OPNET environment to conclude communication factors. These results are used to validate the performance of the proposed control strategy in MATLAB/SIMULINK environment for various communication as well as converter adversities.

Distributed Real-time Control Architecture for ROS-based Modular Robots

Nowadays ROS (Robot Operating System) based platforms have been widely used in state of art robot researches because of providing reliable mechanisms for fast robot development and algorithm reuse. Among them, modular robots are presented as a Distributed Control System (DCS), in which the data supply and the flow rates must be ensured to guarantee a proper execution. Although ROS network architecture provides a solution for distributed communication, it entails some disadvantages. Real-time constraints assurance and large networks management are some of the main problems. Therefore, this works introduces a ROS-compatible solution for Smart Resource services decoupling on modular robots. Smart Resources are defined as cyber-physical systems that provide high-level operation services. The design and analysis of a new distributed communication architecture for accessing Smart Resource services is addressed along this document. This architecture is called ROS Multi-Peer Architecture (RMPA) and features real-time communication, fully decoupled ROS device execution, and device discovery. So, the integration of RMPA in ROS based developments provides realtime access to the high-level supplied by the Smart Resources. This integration promotes the development of ROS-compatible robot modules based on the Smart Resource design. Next, a set of tests is presented to compare RMPA and ROS communication performance. Moreover, a detailed study of the RMPA performance is also addressed. Finally, as a result of these experiments main advantages and withdrawals of this solution are discussed leading to the establishment of future work and enhancements.

Distributed Communication Architecture for Smart Grid Applications

One big challenge in building a smart grid arises from the fast growing amount of data and limited communication resources. The traditional centralized communication architecture does not scale well with the explosive increase of data and has a high probability of encountering communication bottlenecks due to long communication paths. To address this challenging issue, this article presents a distributed communication architecture that implements smart grid communications in an efficient and cost-effective way. This distributed architecture consists of multiple distributed operation centers, each of which is connected to several data concentrators serving one local area and only sends summary or required integrated information to a central operation center. Using this distributed architecture, communication distance is much shortened, and thus data will be delivered more efficiently and reliably. In addition, such a distributed architecture can manage and analyze data locally, rather than backhauling all raw data to the central operation center, leading to reduced cost and burden on communication resources. Advanced metering infrastructure is chosen as an example to demonstrate benefits of this architecture on improving communication performance. The distributed communication architecture is also readily applicable to other smart grid applications, for example, demand response management systems.

A secure and privacy-preserving approach to communications in smart grids

Smart grids are electricity networks that can intelligently integrate the action of all connected users - producers, consumers, and prosumers (i.e., producers and consumers at the same time) - in order to efficiently deliver sustainable, economic and secure electricity supplies. Smart grids rely on a two-way communication infrastructures in which energy measurement data taken at users located smart meters, as well as control information, must be exchanged in real-time or - at least - near real-time, while simultaneously guaranteeing a secure and privacy preserving communication. This paper addresses such a problem by presenting a distributed communication architecture that guarantees the privacy of fine-grained users data while enabling the energy supplier to access aggregate energy measurements and per-user coarse-grained data for billing purposes. The key idea underlying the proposed architecture is to adopt a secure multiparty computation method based on a verifiable secret sharing of the keys used by the smart meters to encrypt their sensitive data. This approach allows to remove the need for any intermediate aggregator element with clear benefits in terms of scalability and robustness.

A methodology for structured ontology construction applied to intelligent transportation systems

The number of computers installed in urban and transport networks has grown tremendously in recent years, also the local processing capabilities and digital networking currently available. However, the heterogeneity of existing equipment in the field of ITS (Intelligent Transportation Systems) and the large volume of information they handle, greatly hinder the interoperability of the equipment and the design of cooperative applications between devices currently installed in urban networks. While the dynamic discovery of information, composition and invocation of services through intelligent agents are a potential solution to these problems, all these technologies require intelligent management of information flows. In particular, it is necessary to wean these information flows of the technologies used, enabling universal interoperability between computers, regardless of the context in which they are located. The main objective of this paper is to propose a systematic methodology to create ontologies, using methods such as a semantic clustering algorithms for retrieval and representation of information. Using the proposed methodology, an ontology will be developed in the ITS domain. This ontology will serve as the basis of semantic information to a SS (Semantic Service) that allows the connection of new equipment to an urban network. The SS uses the CORBA standard as distributed communication architecture.

Decentralized Spatial Decomposition for Traffic Signal Synchronization

The Traffic Signal Synchronization is a traffic engineering technique of matching the green light times for a series of intersections to enable the maximum number of vehicles to pass through, thereby reducing stops and delays experienced by motorists. Synchronizing Traffic Signals ensures a better flow of traffic and minimizes gas consumption and pollutant emissions. In this paper we provide a solution to the the traffic signals problem via simulation. The objective function used in this work is a weighted sum of the delays caused by the signalized intersections, and it is calculated by platoon model. Urban signal timing is a non-convex problem and finding an optimal solution for not very small and simple networks may take long time, wherever possible. For this reason we proposed a spatial decomposition of the network, it is obtained by the distributed consensus algorithms. In this paper we provide a distributed communication architecture for a network of smart traffic lights. Each semaphore shares information in a fully distributed way, only with its neighbors according to the topology of the communication network, hence avoiding to resort to a central authority. Given the subnetwork a surrogate method is applied to solve the Traffic Signal Synchronization problem.

Scalable Distributed Communication Architectures to Support Advanced Metering Infrastructure in Smart Grid

In this paper, we investigate the scalability of three communication architectures for advanced metering infrastructure (AMI) in smart grid. AMI in smart grid is a typical cyber-physical system (CPS) example, in which large amount of data from hundreds of thousands of smart meters are collected and processed through an AMI communication infrastructure. Scalability is one of the most important issues for the AMI deployment in smart grid. In this study, we introduce a new performance metric, accumulated bandwidth-distance product (ABDP), to represent the total communication resource usages. For each distributed communication architecture, we formulate an optimization problem and obtain the solutions for minimizing the total cost of the system that considers both the ABDP and the deployment cost of the meter data management system (MDMS). The simulation results indicate the significant benefits of the distributed communication architectures over the traditional centralized one. More importantly, we analyze the scalability of the total cost of the communication system (including MDMS) with regard to the traffic load on the smart meters for both the centralized and the distributed communication architectures. Through the closed form expressions obtained in our analysis, we demonstrate that the total cost for the centralized architecture scales linearly as O(\lambda N), with N being the number of smart meters, and \lambda being the average traffic rate on a smart meter. In contrast, the total cost for the fully distributed communication architecture is O(\lambda^{2\over 3} N^{2\over 3} ), which is significantly lower.

Design of Multi-Sensor Communication System of Wheelchair Robot Base on the CANopen

This paper presents the communi-cation system of wheelchair robot which is based on CAN (Controller Area Network) bus and made up of PC/104PC, MCU and DSP system, which is distributed communication architecture. In this structure, the PC/104, as upper control computer, achieves communi-cation with the underlying control system MCU (DSP) through the CANopen protocol. At the same time, corresponding communication softwares are designed. Finally, the above-mentioned communication softwares are implemented by the wheelchair robot.

A distributed architecture for multiplayer interactive applications on the Internet

This article describes the design, implementation, and evaluation of MiMaze, a distributed multiplayer game on the Internet, and, more precisely, it describes the design of dedicated transmission control mechanisms. MiMaze is implemented on a completely distributed communication architecture based on the IP multicast protocol suite (RTP/UDP/IP). This is the first work to analyze a distributed interactive game on the multicast Internet. The major element of the MiMaze architecture is a distributed synchronization mechanism that guarantees the consistency of the game regardless of network delay. This article provides on evaluation of the MiMaze game on the MBone, and discusses approaches to monitor and evaluate this new type of application. The main contribution of this work is to show, based on on example, the feasibility of this new family of applications on a best-effort network. It is shown that real-time interactivity can be maintained, provided that some level of inconsistency can be tolerated by the application. This work also highlights the role of multicast as an enabling technology for a real-time Internet.

Layering an open hypermedia system above a distributed communication architecture (abstract)

Layering an open hypermedia system above a distributed communication architecture (abstract)