This paper presents a hierarchical Digital Twin architecture and implementation that uses real-time simulation to emulate the physical grid and support grid planning and operation. With the demand for detailed grid information for automated grid operations and the ongoing transformation of energy systems, the Digital Twin can extend data acquisition by establishing a reliable real-time simulation. The system uses observer algorithms to process model information about the voltage dependencies of grid nodes, providing information about the dynamic behavior of the grid. The architecture implements multiple layers of data monitoring, processing, and simulation to create node-specific Digital Twins that are integrated into a real-time Hardware-in-the-Loop setup. The paper includes a simulation study that validates the accuracy of the Digital Twin, in terms of steady-state conditions, dynamic behavior, and required processing time. The results show that the proposed architecture can replicate the physical grid with high accuracy and corresponding dynamic behavior.

A microgrid is an independent power system that can be connected to the grid or operated in an islanded mode. This single grid entity is widely used for furthering access to energy and ensuring reliable energy supply. However, if islanded, microgrids do not benefit from the high inertia of the main grid and can be subject to high variations in terms of voltage and frequency, which challenge their stability. In addition, operability and interoperability requirements, standards as well as directives have addressed main concerns regarding a microgrid’s reliability, use of distributed local resources and cybersecurity. Nevertheless, microgrid systems are quickly evolving through digitalization and have a large range of applications. Thus, a consensus over their testing must be further developed with the current technological development. Here, we describe existing technical requirements and assessment criteria for a microgrid’s main functionalities to foster harmonization of functionality-level testing and an international conception of system-level one. This framework is proposed as a reference document for assessment frame development serving both microgrid research and implementation for a comprehensive understanding of technical microgrid performance and its current assessment challenges, such as lack of standardization and evolving technology.

Die Digitalisierung der Stationsautomatisierung eröffnet neue Anwendungspotentiale für intelligente Stationsfunktionen in elektrischen Energiesystemen. Die Vernetzung und der Einsatz von IEC 61850 als vereinheitlichter Kommunikationsstandard ist eine wichtige Voraussetzung, erhöhen aber gleichzeitig die Anfälligkeit für IT-Angriffe. Zur Untersuchung der IT-Sicherheit digitaler Stationen wird hierfür eine neu konzipierte cyber-physische Echtzeit-Co-Simulationsplattform vorgestellt. Auf Basis einer Referenzarchitektur eines IP-basierten Umspannwerks wird die Modellierung, Bewertung und Analyse digitaler Stationen für gestörte und ungestörte Betriebsfälle sowie unter Beachtung von IT-Angriffen ermöglicht. Daraufhin werden Ansätze zur Resilienzbewertung sowie Maßnahmen zur IT-Sicherheit für den operativen Betrieb, z. B. die Erkennung cyber-physischer Anomalien, aufgezeigt. The increasing digitalization within station automation enables new applications for intelligent functionalities in substations of electrical power systems. For this, the utilization of IEC 61850 as unified communication standard is a key requirement but also changes the vulnerability for cyber-attacks. For cyber-security investigations of digital substations a cyber-physical real-time co-simulation platform is introduced. A reference architecture of an IP-based substation is presented and enables the modelling, assessment and analysis of digital substation within disturbed and undisturbed grid situations as well as under consideration of cyber-attacks. Based on this, novel approaches and methods for resilience assessment of digital substations and cyber-security measures for operations, e. g. the detection of cyber-physical anomalies, are described and discussed.