Abstract-The evolution toward emerging active distribution networks (ADNs) can be realized via a real-time state estimation (RTSE) application facilitated by the use of phasor measurement units (PMUs). A critical challenge in deploying PMU-based RTSE applications at large scale is the lack of a scalable and flexible communication infrastructure for the timely (i.e., sub-second) delivery of the high volume of synchronized and continuous synchrophasor measurements. We address this challenge by introducing a communication platform called C-DAX based on the information-centric networking (ICN) concept. With a topicbased publish-subscribe engine that decouples data producers and consumers in time and space, C-DAX enables efficient synchrophasor measurement delivery, as well as flexible and scalable (re)configuration of PMU data communication for seamless full observability of power conditions in complex and dynamic scenarios. Based on the derived set of requirements for supporting PMU-based RTSE in ADNs, we design the ICN-based C-DAX communication platform, together with a joint optimized physical network resource provisioning strategy, in order to enable the agile PMU data communications in near real-time. In this paper, C-DAX is validated via a field trial implementation deployed over a sample feeder in a real-distribution network; it is also evaluated through simulation-based experiments using a large set of real medium voltage grid topologies currently operating live in The Netherlands. This is the first work that applies emerging communication paradigms, such as ICN, to smart grids while

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Limited scalability, reliability, and security of todays utility communication infrastructures are main obstacles to the deployment of smart grid applications. The C-DAX project aims at providing and investigating a communication middleware for smart grids to address these problems, applying the informationcentric networking and publish/subscribe paradigm. We briefly describe the C-DAX architecture, and extend it with a flexible resilience concept, based on resilient data forwarding and data redundancy. Different levels of resilience support are defined, and their underlying mechanisms are described. Experiments show fast and reliable performance of the resilience mechanism. I. INTRODUCTION Power distribution networks are undergoing major changes in operational procedures and monitoring, thereby evolving from passive to active networks [1], [2]. Advanced smart monitoring tools result in faster and more reliable real-time state estimation (RTSE) [3], [4]. Especially extensive synchrophasor measurements can achieve a more complete view and improve control of power networks [4], [5], [6]. Main obstacles to the deployment of smart grid (SG) applications are limited scalability, reliability, and security of todays utility communication infrastructures. The National Institute for Standards and Technology (NIST) working group on SGs [7] identified reliability requirements for SG communication flows.The Cyber-secure Data and Control Cloud for power grids (C-DAX) project [8] aims to provide such a communication middleware by applying the emerging information-centric networking (ICN) [9] and publish/subscribe (pub/sub) [10] paradigm to the electric utility network of sensors and controls. The major advantages of C-DAX architecture are resiliency, inter-domain communication, cyber security, flexibility, and support for real-time applications.The main contribution of this paper is a brief description of the overall C-DAX architecture, and a detailed presentation of its flexible resilience concept. Instead of a fixed resilience concept for all SG applications, C-DAX' resilience concept provides four different levels of resilience support, which can be selected per information channel by application developers. Parts of the resilience concept are already implemented in the C-DAX prototype, and will be deployed in a real-world power grid as part of a field trial.

The electrical grid is changing from a centralized system with predictable and controllable power generation to a system integrating large numbers of distributed energy resources including weather-dependent renewables. As a consequence, the future retail energy market for electrical energy will have many more participants and see more volatile prices than today, creating the need for new communication and trading infrastructures facilitating.In this paper, we briefly review PowerMatcher as a possible approach for such an infrastructure, and analytically evaluate its communication characteristics. PowerMatcher is a multiagent based smart grid communication framework developed by TNO which enables market integration of distributed energy resources and automatic demand supply matching. While the trading side of the framework is well understood, there is no study that considers the communication side. Our results show that PowerMatcher enables scalable retail energy transactions with millions of participants requiring only moderate resources on the communication's side. I. INTRODUCTIONElectricity generation is currently changing from a centralized system with predictable and controllable outputs to a system integrating distributed energy resources (DERs) * including weather-dependent renewables. Such renewable energy sources are less predictable and hard to control [2], [3]. The downside is that we will face variations in supply, with periods of higher or lower renewable energy offers. The deficit must be compensated by other energy sources to avoid outages. This will affect future markets for electrical energy.In the future retail energy market (REM), any participant will be able to trade energy in retail energy transactions (RETs), i.e., the future REM will have many more participants than today. Instead of a fixed-price contract model, consumers will have dynamic pricing based on predicted supply and demand [4]. Electricity trading intervals will be in the order of minutes or hours, i.e., significantly shorter than today's accounting intervals [5]. As a consequence, the future REM will see more volatile prices than today. New trading infrastructures are necessary as enabling technology [6], [7], [5], [8] to deal with the increased number of REM participants and changing trading dynamics. The PowerMatcher (PM) communication framework [8], [9] developed by the Netherlands Organisation for Applied

Abstract-The limited scalability, reliability, and security of today's utility communication infrastructures are main obstacles for the deployment of smart grid applications. The C-DAX project aims at providing a cyber-secure publish/subscribe middleware tailored to the needs of smart grids. C-DAX provides end-to-end security, and scalable and resilient communication among participants in a smart grid. This work presents the C-DAX security architecture, and proposes different key distribution mechanisms. Security properties are defined for control plane and data plane communication, and their underlying mechanisms are explained. The presented work is partially implemented in the C-DAX prototype and will be deployed in a field trial.