Power line communications: an implementation of a real time control architecture for smart grid

Negli ultimi anni è aumentata la presenza di risorse energetiche distribuite (DERs) nella rete elettrica. La visione della ``rete intelligente'' (Smart Grid) cerca di introdurre un'infrastruttura di controllo e di comunicazione di tipo distribuito in modo da sfruttare le potenzialità delle DERs e quindi potenziare e modernizzare la rete di distribuzione attuale. Applicandolo alle reti a bassa tensione, la cosiddetta ``Smart Microgrids'', si è sviluppato un banco di prova (testbed) che permette di dimostrare tecniche di riduzione delle perdite di distribuzione. La soluzione adottata bilancia localmente la potenza reattiva della microgrid attraverso il controllo delle risorse locali ottenendo una riduzione della corrente necessaria per alimentare la rete. Inoltre, vengono analizzati i vantaggi nell'usare la linea elettrica come mezzo di comunicazione e vengono evidenziati alcuni standard di comunicazion

Worst-case access delay of HomePlug Green PHY (HPGP) for delay-critical in-vehicle applications

The increasing complexity of automotive electronics has put considerable pressure on automotive communication networking to accommodate in-vehicle information flows. The use of power lines has been a promising alternative to in-vehicle communications because of elimination of extra data cables. In this paper, we focus on the latest HomePlug Green PHY (HPGP) which has been promoted by major automotive manufacturers for green communications with electric vehicles, and study its worst-case access delay performance in supporting delaycritical in-vehicle applications using both theoretical analysis and the simulation. Specifically, we apply Network Calculus as a deterministic modeling approach to evaluate the worst delay and further verify its performance using the OMNeT++ simulation. Evaluation results are also supplemented to compare with legacy methods and provide useful guidelines for developing HPGP based vehicular power line communication systems

POWER LINE COMMUNICATIONS FOR SMART HOME NETWORKS: MODELING, SIMULATION AND OPTIMIZATION

In recent years, research and development efforts are devoted to the deployment of information and communication technology (ICT) within residential buildings and houses, in order to provide services that will increase the quality of life. Although this trend is originated in the late 60’s as a result of the application of industrial automation to residential buildings and houses, i.e., home automation, nowadays, further services are offered to the final users, i.e., home networking and energy management. In fact, a lot of effort is put on the joint delivery of these services in order to make the home, namely the smart home (SH), an integral part of the future smart grid (SG). The concept of SH can be described as a house equipped with electronic systems and appliances, namely, “smart” appliances, which are able to exchange information by means of a communication network. However, these systems are characterized by a broad variety of communication technologies, standards and protocols, so that they often cannot interconnect, and/or interoperate and in some cases even coexist. In our opinion, coexistence, interconnection and interoperability problems represents the bottleneck to a pervasive deployment of smart appliances and systems within residential buildings and houses. To this respect, the first topic that we consider in this thesis is the definition of the SH network architecture and devices, which allows to obtain convergence among smart appliances. To this aim, a survey of the communication technologies, standards, protocols and also media, which can be used for SH applications, is necessary in order to define a network topology that is able to be scalable, extensible, and rather reliable. Moreover, in order to achieve interconnectivity among “smart” appliances, we define a shared common layer that is able to manage heterogeneous lower layers allowing network convergence. Once defined the SH network architecture and its network devices, we focus on power line communication (PLC) technologies and we implement a network testbed in order to evaluate some of the functionalities of the SH network within real environments. From the analysis of field trial data, we are able to highlight performances and disadvantages of two representative narrow band PLC (NB-PLC) solutions. Furthermore, exploiting the network testbed where broadband PLC (BB-PLC) technology is used to provide an Ethernet backbone for NB-PLC devices, we achieve interconnectivity between heterogeneous devices and we observe a significant improvement of the performances. Although NB-PLC technologies have been conceived for the development of low data rate applications and, in particular, for automatic meter reading (AMR), we focus our attention on the G3-PLC technology, for which we propose enhancements at the medium access control (MAC) sub-layer to allow the implementation of SH applications that could potentially require higher data rate than AMR. The G3-PLC technology has been taken into account since (i) it has been used as baseline technology for the development of popular communication standards for SG applications, and (ii) we have found, from the field trials, that the performance of NB-PLC may be poor in large houses where the signal is strongly attenuated because it spans large distances and crosses different circuit breakers (CBs), e.g., in multi-floor houses. Furthermore, an innovative cross-platform simulator that allows to realistically simulate the G3-PLC technology up to the network layer is presented. The proposed cross-platform consists of two different simulators jointly connected: one for the physical (PHY) layer and one for the data link layer (DLL)/network layer (NL). The PHY layer simulator is implemented in MATLAB, while the DLL/network simulator in OMNeT++. A convergent network architecture that permits the integration of the G3-PLC technology within a switched Ethernet network is also presented with the aim of improving the G3-PLC performance in large scale houses/buildings. The performance of the considered communication technology are presented through extensive numerical results for the in-home application scenario. Finally, the cross-platform simulator is used to evaluate G3-PLC systems for SG applications in the access network scenario. This is fundamental since the interaction of the outside world, i.e., the access network, with the SH is mandatory in order to achieve and exploit the SG concept. Moreover, to improve the performance and coverage of G3-PLC, a simple adaptive tone mapping algorithm together with a routing algorithm are also presented.Ricerca condotta all'interno del WiPLi Lab/Wireless and Power Line Communications LaboratoryopenDottorato di ricerca in Ingegneria industriale e dell'informazioneopenDI BERT, Luc

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

Ultra wideband gigabit powerline communication

PhDPowerline Communication (PLC) has long been established for low data rate applications by the electric supply companies. Since 1991, the European CENELEC standard EN 50065 has ruled the use of 3 - 148.5KHz frequency range for narrow band PLC applications. Sim- ilar standard has been established by the IEEE in the US, where a frequency range of 50 - 450KHz is available. The fast growth of Internet since the 1990s accelerated the demands for digital communication services. Furthermore, with the develop- ment of in-home networking, there is a need to establish high speed data links between multiple household devices. This makes PLC sys- tems march rapidly into the high frequency range above 1MHz. Exist- ing broadband PLC system in the 1.6 - 30MHz frequency range only provides data rates smaller than 200Mbps. With the growing demand of multimedia services such as High De nition (HD) video streaming, much faster transmission speed up to Gigabits per second is required and this can be achieved by increasing the operating frequencies. Ultra Wideband (UWB) transmission in free space provides extremely broad bandwidth for short-range, high data rate applications. If UWB signals could be transmitted over the powerline channels in the high frequency range above 30MHz, data rates up to gigabits per second could be achieved. In this thesis, the possibility of implementing ultra wideband trans- mission over the low voltage indoor powerline is investigated. The starting point is to understand the signal propagation characteristics over powerline cables, in the UWB frequency range. Experimental re- sults indicate that the signal degrades at an acceptable rate over the mains cable in a scaled down UWB frequency band (50MHz - 1GHz), which provides a potential operation band for UWB over PLC ap- plications. Key component for the PLC system, a broadband Radio Frequency (RF) coupler is designed and developed, to introduce UWB signals to the transmission channel. With the channel properties and coupling unit, extensive experimental investigations are carried out to analyse the powerline network environment, including channel loss, noise and radiated emission. Furthermore, theoretical channel capac- ity and link budget are derived from measured parameters. It is shown that the indoor powerline is a suitable media for data transmission in the high frequency range from 50 to 550MHz in the home environment. Finally, system level performance is analysed by modelling the Phys- ical Layer (PHY) data transmission. The Multiband-OFDM UWB proposal for IEEE 802.15.3a standard is used to predict the transmis- sion performance under di erent propagation paths and data rates. The research work conducted in this project has proven that UWB over PLC is highly feasible for future in-home applications. With the global promotion of smart grid applications, UWB over PLC will play an important role in providing high speed data transmission over the power networks

Transmission haut-débit sur les réseaux d'énergie: principes physiques et compatibilité électromagnétique

Power Line Communications consist of transmitting data by reusing the existing powerline as a propagation medium. Powerline networks represent a challenging environment for broadband communications, since they have not been designed for the transmission of high frequency signals. This Habilitation degree thesis presents our research on transmission physics and electromagnetic compatibility for in-home powerline networks. This research has been conducted since 2007 in the framework of a collaboration between Orange Labs and Telecom Bretagne, involving my supervision of three Ph.D. theses defended in 2012, 2013 and 2015, as the principal advisor.La technologie Courant Porteur en Ligne consiste à transmettre des données en réutilisant le réseau électrique classique en tant que support de propagation. Les réseaux d'énergie sont des environnements difficiles pour les communications à haut débit, car ils n'ont pas été conçus pour la transmission d'un signal à haute fréquence. Ce mémoire d'Habilitation à Diriger des Recherches présente mes travaux concernant la physique de la transmission et les aspects de Compatibilité Electro-Magnétique (CEM) pour le réseau électrique domestique. Ils ont été réalisés à partir de 2007 dans le cadre d'une collaboration entre Orange Labs et Telecom Bretagne, notamment à travers trois thèses soutenues en 2012, 2013 et 2015. Après une introduction générale à la technologie CPL, le manuscrit décrit l'environnement de propagation dans les réseaux d'énergie en termes de canal et de bruit électromagnétique. Les principes de la modélisation du canal CPL sont illustrés à partir de la problématique d'identification des trajets de propagation. L'une des principales évolutions du domaine concerne l'application de la technologie Multiple Input Multiple Output (MIMO) aux communications sur réseaux d'énergie. Nos études expérimentales ont démontré que l'adaptation de cette technique issue du domaine de la radio permet un doublement de la capacité de transmission. Nous présentons les campagnes de mesure réalisées au sein d'Orange Labs et du groupe Specialist Task Force 410 de l'ETSI. A partir de ces données, des modèles statistiques de canal de propagation MIMO et de bruit multi-capteurs ont été élaborés. En termes d'émission électromagnétique, la bande utilisée par les systèmes CPL est déjà occupée par d'autres services (radio amateur, radiodiffusion en ondes courtes). Nous décrivons les contraintes CEM des systèmes CPL et abordons les techniques de CEM cognitive, consistant à optimiser les ressources spectrales en tenant compte de la connaissance de l'environnement du système. En particulier, la technique de retournement temporel est étudiée pour la mitigation du rayonnement involontaire et sa performance est étudiée de manière expérimentale. Enfin, le manuscrit présente la problématique de l'efficacité énergétique des systèmes CPL. Nous présentons les mesures expérimentales réalisées afin de modéliser la consommation de modems classiques et MIMO. D'autre part, la configuration de communication en relais a été étudiée, afin d'évaluer le gain de ce mode de transmission en termes de consommation énergétique. A l'avenir, ces travaux pourront être étendus aux réseaux de distribution en basse et moyenne tension, pour le développement et l'optimisation des réseaux d'énergie intelligents, ou Smart Grids

Opportunistic Routing with Network Coding in Powerline Communications

Opportunistic Routing (OR) can be used as an alternative to the legacy routing (LR) protocols in networks with a broadcast lossy channel and possibility of overhearing the signal. The power line medium creates such an environment. OR can better exploit the channel than LR because it allows the cooperation of all nodes that receive any data. With LR, only a chain of nodes is selected for communication. Other nodes drop the received information. We investigate OR for the one-source one-destination scenario with one traffic flow. First, we evaluate the upper bound on the achievable data rate and advocate the decentralized algorithm for its calculation. This knowledge is used in the design of Basic Routing Rules (BRR). They use the link quality metric that equals the upper bound on the achievable data rate between the given node and the destination. We call it the node priority. It considers the possibility of multi-path communication and the packet loss correlation. BRR allows achieving the optimal data rate pertaining certain theoretical assumptions. The Extended BRR (BRR-E) are free of them. The major difference between BRR and BRR-E lies in the usage of Network Coding (NC) for prognosis of the feedback. In this way, the protocol overhead can be severely reduced. We also study Automatic Repeat-reQuest (ARQ) mechanism that is applicable with OR. It differs to ARQ with LR in that each sender has several sinks and none of the sinks except destination require the full recovery of the original message. Using BRR-E, ARQ and other services like network initialization and link state control, we design the Advanced Network Coding based Opportunistic Routing protocol (ANChOR). With the analytic and simulation results we demonstrate the near optimum performance of ANChOR. For the triangular topology, the achievable data rate is just 2% away from the theoretical maximum and it is up to 90% higher than it is possible to achieve with LR. Using the G.hn standard, we also show the full protocol stack simulation results (including IP/UDP and realistic channel model). In this simulation we revealed that the gain of OR to LR can be even more increased by reducing the head-of-the-line problem in ARQ. Even considering the ANChOR overhead through additional headers and feedbacks, it outperforms the original G.hn setup in data rate up to 40% and in latency up to 60%.:1 Introduction 2 1.1 Intra-flow Network Coding 6 1.2 Random Linear Network Coding (RLNC) 7 2 Performance Limits of Routing Protocols in PowerLine Communications (PLC) 13 2.1 System model 14 2.2 Channel model 14 2.3 Upper bound on the achievable data rate 16 2.4 Achieving the upper bound data rate 17 2.5 Potential gain of Opportunistic Routing Protocol (ORP) over Common Single-path Routing Protocol (CSPR) 19 2.6 Evaluation of ORP potential 19 3 Opportunistic Routing: Realizations and Challenges 24 3.1 Vertex priority and cooperation group 26 3.2 Transmission policy in idealized network 34 3.2.1 Basic Routing Rules (BRR) 36 3.3 Transmission policy in real network 40 3.3.1 Purpose of Network Coding (NC) in ORP 41 3.3.2 Extended Basic Routing Rules (BRR) (BRR-E) 43 3.4 Automatic ReQuest reply (ARQ) 50 3.4.1 Retransmission request message contents 51 3.4.2 Retransmission Request (RR) origination and forwarding 66 3.4.3 Retransmission response 67 3.5 Congestion control 68 3.5.1 Congestion control in our work 70 3.6 Network initialization 74 3.7 Formation of the cooperation groups (coalitions) 76 3.8 Advanced Network Coding based Opportunistic Routing protocol (ANChOR) header 77 3.9 Communication of protocol information 77 3.10 ANChOR simulation . .79 3.10.1 ANChOR information in real time .80 3.10.2 Selection of the coding rate 87 3.10.3 Routing Protocol Information (RPI) broadcasting frequency 89 3.10.4 RR contents 91 3.10.5 Selection of RR forwarder 92 3.10.6 ANChOR stability 92 3.11 Summary 95 4 ANChOR in the Gigabit Home Network (G.hn) Protocol 97 4.1 Compatibility with the PLC protocol stack 99 4.2 Channel and noise model 101 4.2.1 In-home scenario 102 4.2.2 Access network scenario 102 4.3 Physical layer (PHY) layer implementation 102 4.3.1 Bit Allocation Algorithm (BAA) 103 4.4 Multiple Access Control layer (MAC) layer 109 4.5 Logical Link Control layer (LLC) layer 111 4.5.1 Reference Automatic Repeat reQuest (ARQ) 111 4.5.2 Hybrid Automatic Repeat reQuest (HARQ) in ANChOR 114 4.5.3 Modeling Protocol Data Unit (PDU) erasures on LLC 116 4.6 Summary 117 5 Study of G.hn with ANChOR 119 5.1 ARQ analysis 119 5.2 Medium and PHY requirements for “good” cooperation 125 5.3 Access network scenario 128 5.4 In-home scenario 135 5.4.1 Modeling packet erasures 136 5.4.2 Linear Dependence Ratio (LDR) 139 5.4.3 Worst case scenario 143 5.4.4 Analysis of in-home topologies 145 6 Conclusions . . . . . . . . . . . . . . . 154 A Proof of the neccessity of the exclusion rule 160 B Gain of ORPs to CSRPs 163 C Broadcasting rule 165 D Proof of optimality of BRR for triangular topology 167 E Reducing the retransmission probability 168 F Calculation of Expected Average number of transmissions (EAX) for topologies with bi-directional links 170 G Feedback overhead of full coding matrices 174 H Block diagram of G.hn physical layer in ns-3 model 175 I PER to BER mapping 17

LPTV-Aware Bit Loading and Channel Estimation in Broadband PLC for Smart Grid

Power line communication (PLC) has received steady interest over recent decades because of its economic use of existing power lines, and is one of the communication technologies envisaged for Smart Grid (SG) infrastructure. However, power lines are not designed for data communication, and this brings unique challenges for data communication over power lines. In particular for broadband (BB) PLC, the channel exhibits linear periodically time varying (LPTV) behavior synchronous to the AC mains cycle. This is due to the time varying impedances of electrical devices that are connected to the power grid. Another challenge is the impulsive noise in addition to power line background noise, which is due to switching events in the power line network. In this work, we focus on two major aspects of an orthogonal frequency division multiplexing (OFDM) system for BB PLC LPTV channels; bit and power allocation, and channel estimation (CE). First, we investigate the problem of optimal bit and power allocation, in order to increase bit rates and improve energy efficiency. We present that the application of a power constraint that is averaged over many microslots can be exploited for further performance improvements through bit loading. Due to the matroid structure of the optimization problem, greedy-type algorithms are proven to be optimal for the new LPTV-aware bit and power loading. Significant gains are attained especially for poor (i.e. high attenuation) channel conditions, and at reduced transmit-power levels, where the energy per bit-transmission is also low. Next, two mechanisms are utilized to reduce the complexity of the optimal LPTV-aware bit loading and peak microslot power levels: (i) employing representative values from microslot transfer functions, and (ii) power clipping. The ideas of LPTV-aware bit loading, complexity reduction mechanism, and power clipping are also applicable to non-optimal bit loading schemes. We apply these ideas to two additional sub-optimal bit loading algorithms that are based on even-like power distribution for a portion of the available spectrum, and demonstrate that similar gains in bit rates are achieved. Second, we tackle the problem of CE for BB PLC LPTV channels. We first investigate pilot based CE with different pilot geometry in order to reduce interpolation error. Block-type, comb-type, and incline type pilot arrangements are considered and a performance comparison has been made. Next we develop a robust CE scheme with low overhead that addresses the drawbacks of block-type pilot arrangement and decision directed CE schemes such as large estimation overhead for block-type pilot geometry, and difficulty in channel tracking in the case of sudden changes in the channel for decision directed approaches. In order to overcome these drawbacks, we develop a transform domain (TD) analysis approach to determine the cause of changes in the channel estimates, which are due to changes in the channel response or the presence of impulsive noise. We then propose a robust CE scheme with low estimation overhead, which utilizes pilot symbols placed widely apart and exploits the information obtained from TD analysis as a basis for switching between various CE schemes. The overhead of the proposed scheme for CE is low, and sudden changes in the channel are tracked affectively. Therefore, the effects of the LPTV channel and the impulsive noise on CE are mitigated. Our results indicate that for bit and power allocation, the proposed reduced complexity LPTV-aware bit loading with power clipping algorithm performs very close to the optimal LPTV-aware bit loading, and is an attractive solution to bit loading in a practical setting. Finally, for the CE problem, the proposed CE scheme based on TD analysis has low estimation overhead, performs well compared to block-type pilot arrangement and decision directed CE schemes, and is robust to changes in the channel and the presence of impulsive noise. Therefore, it is a good alternative for CE in BB PLC