## 4 Evolution of the Electricity Distribution Networks--A Finnish Case
### Sundom Smart Grid  
The evolution of a typical suburban or rural area grid in Nordic countries is developed via the Sundom smart grid study case. Figure 3 presents an outline of the fictitious future design for the Sundom smart grid, located in a suburban/rural area. There are around 2500 residential and small commercial electricity users (metering points). The peak power is around 8 MW and increasing since the housing of the area is growing. There is a 3.6 MW WT connected with its own feeder to the MV bus. The current real system is represented on the left side, where the fictitious connections are denoted with dashed lines. There are two primary substations connected between the 110 kV high voltage (HV) bus and the 21 kV MV bus in the futuristic outline of the intelligent microgrid network phase. Both MV distribution networks comprise the feeders supplying electricity to the customers and the feeders to connect the WT and PS-BESS for power supply to the distribution grid and the AS. There are secondary substations along with the MV feeders, which connect 0.4 kV LV distribution networks to the power system. The LV distribution networks include households and small commercial customer types. At the customer premises, there exist DG units and BESS. For heating, the customers use the electric heating systems, which can be direct, partially storing, storing, or heat-pump systems. District heating is available in the suburban area.  
This paper focuses on ADNM through DERs at the different evolution phases of the electricity distribution networks at the location of the Sundom smart grid. In the developed network scenarios, WT, PV, and CHP units are considered the DG units to be used in ADNM. Controllable loads can comprise loads in the customer premises and a part of the distribution network (e.g., a microgrid). The energy storage systems (ESSs) are considered to be BESS and the district heating storage system. Energy conversion is regarded between electricity and heating and later between electricity and liquid fuel (power-to-liquid-to-power). The primary focus on the AS case studies is the DSM via marketplaces, which can be offered at the first stage by aggregated customers and later by an energy community or the microgrid owners. ASs can be offered for TSO's power balancing or frequency stability support and later evolution phases for voltage control. The second focus is on the local ASs, which are envisioned for the DSO's network management purposes for voltage control. The DG owners, the aggregated customers, and later the microgrid owners can offer local ASs. A probable scenario could also be active power control of the customers' generation  
Figure 3: Outline of the developing electricity distribution networks, futuristic case of the Sundom smart grid.  
units for the DSO's ASs. However, these cases are not developed in this research and are left to future research.  
The following describes the future electricity distribution network operations and management in a behavioral (Section 5) and structural (Section 6) manner. The descriptions use the previously presented review on electricity distribution network development, the definitions of the evolution phases, and the outline of Figure 3. The operational scenarios and the structural representations are developed considering the real distribution network to create a concrete roadmap of the network development and a description of the management architecture schemes. The current system is used to reference which of the future system's scenarios are built by increasing the DERs. The method can be used generally in the roadmap and management system architecture scheme creation, whereas the outcome is representations suitable for similar networks in type and environmental conditions.