# Towards Flexible Distribution Systems: Future Adaptive Management Schemes
## 3 Future Adaptive Control and Management Methods
Different active power \(P\) and reactive power \(Q\) related flexibility services from the DER units' can be realized by various inverter local control modes, such as constant power factor (\(cos\phi\)), fixed \(Q\), \(Q\)(\(P\)), \(cos\phi\)(\(P\)), \(QU\)/\(Volt\)-\(V\)Ar, \(PU\) and \(Pf\), where \(f\) is the frequency and \(U\) is voltage. \(QU\)-droop control mode has been typically used with inverter-based DG units connected in distribution networks [67; 68]. In order to avoid, for example, distribution network-connected PV unit active power \(P\) unnecessary curtailment, \(QU\)-droop is used as a primary local voltage control method and \(P\) curtailment related \(PU\)-droop as a secondary method. In order to achieve simultaneously the best possible voltage level control in both MV and LV networks, the distribution system connected DER units' voltage control settings, and principles need to be coordinated with, for example, the HV/MV substation on-load tap changer (OLTC) settings. In order to achieve more optimized operation and further improve DG, such as PV, hosting capacity in distribution networks, reduce network losses [69; 70; 71; 72], and enable frequency or voltage control participation, etc., enhanced state estimation and coordinated operation is required [73; 74; 75; 76; 77]. Already a low level of communication between DER units could enable the achievement of better control settings and improved performance [78]. In the future, in addition to \(P\)- and \(Q\)-control-based flexibility services, DER units (Figure 3) could also provide other local power quality improvement-related services for DSOs. Such services could be, for example, compensation of unbalance (current and voltage) between three phases as well as compensation of current and voltage harmonics which are expected to increase in LV networks in the future, e.g., due to increased EV and PV integration. In the following, flexible and adaptive technical management solutions considered in this paper for distribution network-connected flexibilities improved use for local and system-wide services are shown in Figure 3. The target of these new adaptive control and management methods is to maximize the availability of all LV network-connected flexibilities for different DSO and TSO needs during the evolution (Table 1). These proposed adaptive technical management solutions can be seen as flexibility services, and they should be also considered as part of future collaborative TSO-DSO market schemes. The main principles and settings proposed in Figure 3 are today/in stage 1 (Table 1) decentralized/local and in the near future could be used without or with minimum communication. However, in the future/stages 2-3 (Table 1), increased use of real-time measurements from the MV and LV network with some centralized ANM functions and active participation on different markets and marketplaces will also require increased use of reliable, cost-efficient, low-latency communication. In the future, when more real-time measurements will become available for accurate state estimation and related ANM functions, the setting values of OLTCs and DER unit local \(QU\)- and \(PU\)-droops could also be more frequently adapted. This means that short- (time of day) forecasts and locational aspects would be increasingly considered with some combined centralized/decentralized multi-objective ANM functionality. Adaptive and flexible \(QU\)-, \(PU\)- and \(Pf\) -droop functions could enable local operation optimization at the DSO level by updating the dead-zone values and activation limits of droop functions in a (a) seasonal/monthly/weekly/daily manner (stage 1-2) and (b) a more real-time manner (stage 2-3) [79]. Advanced ICT (5/6G wireless communication and edge computing-based solutions) in stage 2-3 could also enable increasingly decentralized/combined (centralized+decentralized/supervised decentralized) solutions, e.g., at the secondary substation level as well as different local energy and flexibility (peer-to-peer) market schemes.