The current development of the power grid towards a Smart Grid advances the complexity of the system, involving active control, new software components and large amounts of data. This, in turn, requires new approaches for the ICT infrastructure to guarantee real-time capability and reliability. In this work, we present our design of a novel infrastructure for smart substations in the transmission grid, applying the concept of virtualization to substation devices. Since virtualization has already been successfully applied for fault-tolerant and dependable computer systems, it promises to be a valuable concept for substation automation. However, virtualization poses additional challenges to the real-time capability of the substation infrastructure in terms of additional traffic and resource allocation. For analysing the impact on substation communication, we apply simulations and the analytical technique Network Calculus to provide guarantees on the performance of the proposed communication infrastructure. In addition, the performance of the execution platform is studied empirically, measuring occurring delays in a test-bed set-up. Finally, we combine the results from both evaluations to derive an end-to-end delay bound for a power grid related example. Our results show that, other than Fast Ethernet, Gigabit Ethernet networks can guarantee the secure operation of virtualized, fault-tolerant substation infrastructures.

For simulating cyber-physical energy systems, distinct simulation domains need to be integrated for a comprehensive analysis of the interdependent subsystems. In particular, continuous time-based power system simulation and discrete event-based simulation of information and communication technology (ICT) networks are critical for investigating future smart grids. This paper presents the novel cosimulation environment INtegrated coSimulation of Power and ICT systems for Real-time Evaluation (INSPIRE) of power and ICT systems using the high-level architecture (HLA) (IEEE Std. 1516-2010). By applying the HLA standard, the environment is extendable to other simulation domains and a variety of functionalities and models, like thermal load models and additional third-party tools. Moreover, the HLA enables computational performance by distributed execution of each simulator on its own hardware and, thus, the applicability to realistic large-scale scenarios. INSPIRE has been designed under consideration of industrial standards [IEC 61850,object linking and embedding (OLE) for process control (OPC), and the common information model (CIM) (IEC 61968/61970)] in order to enhance interoperability, and to develop and validate solutions close to practice. The simulation results underline the interdependencies of power and ICT systems, and the necessity of an integrated analysis.

Driven by the increasing application of Smart Grid technologies in today's power systems, communication networks are becoming more and more important for exchanging monitoring, control and protection information on local and wide area level. For communication the IEC 61850 standard is a candidate for the Smart Grid and has been introduced for Substation Automation Systems (SAS) some years ago. IEC 61850 provides interoperability among various manufactures and enables systemwide communication between intelligent components of future power systems. However, as IEC 61850 addresses Ethernet (ISO/IEC 8802-3 family) as network technology, especially high performance aspects of Ethernet have become increasingly important for time-critical communication within substation automation systems. In this paper we introduce the generic architecture of IEC 61850 and present our modelling approach for evaluating high performance and real-time capability of communication technologies for future smart grid application. First, we give a short overview of the IEC 61850 protocol and present communication flows in substation automation systems according to the standard. Here we focus on substation automation at bay level, located inside an exemplary substation node taken from the IEEE 39-bus power system network. Afterwards we demonstrate our modeling approach for communication networks based on IEC 61850. For performance evaluation we developed a simulation model along with an analytical approach on basis of Network Calculus, enabling to identify worst case boundaries for intra-substation communication. Finally results for simulative and analytical modelling are provided and cross validated for two bay level scenarios, showing the applicability of Network Calculus for real-time constrained smart grid communication.