# Towards Flexible Distribution Systems: Future Adaptive Management Schemes
## 2 Evolution of Flexible Distribution System
### New Operation and Planning Methods for Resilient Digital Distribution Systems  
Future societies will be increasingly dependent on the continuous availability of electricity. Simultaneously, the frequency and intensity of extreme weather events as well as the risk of potential cyber- and physical attacks will also increase. Therefore, the resilience and security of the power system are becoming more critical. Many needed resilience improvements will have to occur on the distribution network/system level. Resilience can be defined as the ability of the system to withstand and reduce the magnitude or duration of disruptive events and rapidly recover from these events in a self-healing manner. This kind of high-impact, low-probability (HILP) event (typically also with sufficiently long duration) can be, for example, due to extreme weather, cyber- and physical attacks, loss of essential data/ICT infrastructure, electromagnetic and geomagnetic disturbances, and fuel security [17]. Future resilient and secure electricity distribution systems should withstand disruptive events and reduce the magnitude and duration of any power failures that do occur. In the future, energy system operation and planning principles must be based on use of flexibilities as well as maximization of system resiliency. Electricity distribution and transmission network zones with flexible DER and the ability to operate in intended island operation are typical for a definition of a microgrid. Microgrids could be seen as building blocks of future resilient and secure electricity distribution networks. During transmission or distribution network downtimes due to storms, natural disasters, or external attacks (physical or cyber), a microgrid with flexible energy resources, such as energy storages, is able to continue electricity supply to customers in islanded operation mode and improve supply security. On the other hand, the intended microgrid island operation use requires future distribution network control and protection methods to be more active and adaptive. Many of these future control and protection methods will use an increased number of time-synchronized measurements and advanced ICT technologies (such as wireless 5G, cloud, or edge services with big data analytics). Therefore, from a system resiliency viewpoint, aspects related to, for example, cyber-security, reliable time synchronization (e.g., IEEE 1588, synchrophasors, etc. ), self-healing and backup power (also for the wireless communication) strategies, redundant low-latency communication solutions as well as local backup solutions (not based on communication) for control and protection will be of key importance. The future power system management, control, and protection functionalities will be highly dependent on different ICT solutions and the correctness of measured and communicated data. Therefore, cyber-attacks such as false data injection can be considered as an increased risk for secure and stable operation of the power system and the related functionalities. However, false data injection must be distinguished from different power system fault situations as well as false measurements due to measurement errors of faulty measurement devices (e.g., current/voltage sensors or measurement transformers). Different ML- and AI-based techniques also have great potential to be used for these purposes.