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As real-time applications in information technology (IT) and operational technology (OT) advance, new innovative concepts become possible. IT/OT convergence opens new pathways to design and operate intelligent cyber-physical systems, such as the Digital Twin (DT) concept, which has been discovered as key technology by several industries. This paper describes how centralized and decentralized DTs can help to monitor and control future power systems with special consideration of their interaction in case of corrupted communication from cyber-attacks. While the virtual representation of substations is regarded from the edge computing perspective the control room of the interconnected power system represents the centralized perspective. The concepts allows to have a system wide perspective, while also keeping detailed information at hand. The future system operator in the control room will benefit from services provided by DTs analytical and control features, rising resilience to cyber-physical anomalies and enhance situational awareness.

The Kriegers Flak combined grid solution (KF CGS) will interconnect the eastern synchronous area of Denmark and Germany by extending the existing high-voltage alternating current (HVAC) offshore wind farm infrastructure in the Baltic Sea. In contrast to conventional point-to-point interconnectors, the extension creates a meshed submarine grid (MSG) which includes an interconnector and wind farm collectors to the countries using the same equipment. Denmark East as part of the Nordic system and 50 Hertz as part of the synchronous Continental European grid are asynchronous to each other, which makes a frequency transformation necessary. The interconnection will be realised by a high-voltage direct current (HVDC) back-to-back (BtB) converter in voltage source converter technology located at the German end of the interconnector. The BtB and the entire HVAC MSG between Denmark and Germany will be controlled by a so-called master controller for interconnector operation (MIO). The KF CGS will integrate offshore wind power generation, increase the security of supply and enhance integration of regionally produced renewable energy. This study describes the overall infrastructure of the KF CGS and the MIO functions. A model-based evaluation of those shows the behaviour of the HVAC/HVDC MSG in normal operation and in the case of contingencies.

The scope of this survey is the phasor based event detection under cyber security constraints in modern transmission control centers. A general concept for a physical and cyber event detection is developed as a combination of state-of-the-art disturbance classification and cyber-attack detection methods. This requires the incorporation of heterogeneous data sources and advanced data fusion and analysis techniques. An enhanced and robust recognition of the current grid situation is proposed to distinguish between different scheduled and unscheduled grid events. Furthermore, Digital Twins are considered as new promising technology for control centers and potential benefits for physical and cyber event detection are described.

In the wake of the widespread deployment of renewable energy sources (RESs) and the introduction of other distributed energy technologies, the grid exhibits faster and more intricate dynamics. A lot of attention is therefore being put on automated grid management systems, which entail a shift in the role and tasks of human operators in the control rooms (CRs). Given the rapid pace of development, the question ultimately arises if human guidance is necessary at all to safely operate the grid. This work investigates the prospective role of the human operators in CRs under consideration of cognitive challenges in highly automated power systems, aiming to maintain safe and efficient grid operation. A review on relevant literature casts light on the scope of influence of automated grid management systems, the operational states of power system that will still require human assistance, as well as activities and interactions. Finally, recommendations on the design of decision support systems (DSS) supporting humans in their future role are provided.

Future grid control center demand for more frequent communication to field devices with a higher degree of details. A unique demonstrator for dynamic grid control center together with a real-time hybrid grid simulator and its communication infrastructure will be presented in this paper. It includes hardware-in-the-loop HVDC models, state of the art measurement units like PMUs and an embedded control system with a realistic distance to the real-time grid model. To realize completely new functions for the control center and new control strategies for HVDC systems and generators in the grid, modern communication protocols are in use to ensure fast interaction between all components. With this platform, the challenges of the energy transition can be studied and new concepts for observability and controllability of the grid can be developed.

The ongoing transformation of the energy transmission system leads to new requirements regarding online surveillance and controllability during online operation. The introduction of VSC-based HVDC-systems provides a powerful tool to support the existing AC-system by means of preventive optimization and curative actions. This paper introduces new control center applications that support system operators in the identification of critical contingency events and the application of countermeasures. The paper introduces suitable control center applications and describes their application in a demonstrator system.

Erratum: Kriegers flak-combined grid solution: coordinated cross-border control of a meshed HVAC/HVDC offshore wind power grid - Withdrawn 03/09/2018

The development of power system control centers has always been linked to the evolving of new technologies and innovative concepts. Switching to IP/TCP-based communication was one mayor evolutionary step in the past. Now, new precise time-synchronized phasor measurement units (PMU) based monitoring tools are on the rise and enable dynamic system observation. Future control centers for power systems can profit from this development, enlarging the observability and rising operator situation awareness. The next evolutionary step in control center technology may be the utilization of the Digital Twin concept. Its abilities to depict the actual and possible future system state, makes it an inevitable solution for further improvement of power system monitoring and control systems. This paper discusses recent developments of control center technology and introduces a new concept of a Digital Twin centric control center architecture which is based on a dynamic simulation engine called dynamic digital mirror.

New technologies, such as HVDC-links, will play a major role in future transmission system operation. The application of HVDC systems or flexible AC transmission systems (FACTS), introduce new fast dynamics, which add controllability to the power system. Additionally, state of the art technology such as phasor measurement unit (PMU) based wide area monitoring systems (WAMS) enables new methods for the next generation of power system monitoring and control systems. To develop new functionalities for control centers a new development platform for dynamic simulation studies of control and operation functionalities for AC-HVDC systems is introduced. Therefore, a detailed understanding of every component of the distributed system is required. Hence, this paper discusses the components of the development platform comprising a real-time hardware in the loop (HIL) simulation system, the communication system and the control center itself. Furthermore, first new control center functionalities are also described in this paper.