Abstract-Increasing penetration of renewable energy resources (RES) and electrification of services by implementing distributed energy resources (DER) has caused a paradigm shift in the operation of the power system. The controllability of the power system is predicted to be shifted from the generation side to the consumption side. This transition entails that the future power system evolves into a complex cyber-physical energy system (CPES) with strong interactions between the power, communication and neighboring energy systems. Current power system security assessment methods are based on centralized computation and N-1 contingencies, while these risks should still be considered in the future CPES, additional factors are affecting the system security. This paper serves as a review of the challenges entailed by transforming the power system into a CPES from a security assessment perspective. It gives an indication of theoretical solutions to CPES challenges and proposes a new framework for security assessment in CPES.

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Denmark has one of the most aggressive renewable energy strategies in the world; however, large penetrations of fluctuating renewable energy resources will pose new problems in the Danish power system. Demand response (DR) has the potential to mitigate these problems by providing a new source of flexibility. This paper estimates the technical resource potential of residential DR in Denmark. We focus on DR that is non-disruptive to the consumer, meaning that DR actions harness inherent load flexibility and are not noticeable by the consumer. We build on existing methodologies for computing DR technical resource potentials, and use real data from Denmark. We find that country-wide load flexibility is on the order of GWs and GWhs, and will increase drastically over the next 20 years due to electrification of space heating systems and vehicles. However, we also find that flexibility is time-varying on timescales of hours to months, and this variability will become more pronounced with electrification.

In the modern power system, both local and centralized reactive power control strategies for photovoltaic (PV) plants, are proposed and compared. While local control improves the network security, it lacks the optimization benefits from centralized control strategies. Therefore, this paper considers the coordination of the two control strategies, depending on external impact from the weather system and consumer behavior, in a low voltage (LV) distribution feeder. Through modeling and simulation in an established real-time cyber-physical simulation platform, the LV network is evaluated with both local and centralized control. A set of boundaries for coordinating between the two strategies are identified, which can help network operators in deciding suitable control in different operating situations. Furthermore, the cyber-physical simulation platform, is used to study the impact of physical perturbations, i.e. changes in irradiance and consumption, and cyber disturbances, in form of communication channel noise, is evaluated for the control strategies. Results show how small and large disturbances in the cyber system affects the centralized control strategy optimizer performance.