Assessment of impact on power flow by DER utilization under grid congestion management using actual distribution network model

Conventional countermeasures, such as reinforcing substations or curtailing PV output, entail economic and operational drawbacks. While reinforcement is a reliable long-term solution, it requires substantial construction time, whereas curtailment reduces opportunities for renewable utilization. As an alternative, leveraging existing distributed energy resources (DERs), such as grid-scale batteries and data centres, to absorb surplus PV generation has recently gained attention due to its potential to mitigate congestion without reducing renewable output or installing new infrastructure. To utilize DERs for grid services, a systematic congestion mitigation procedure is required. In the assumed operation scheme, DERs are treated as utilityowned assets participating through a dedicated trading platform. First, the required amount of

DER control to relieve congestion is estimated based on grid conditions. Then, through marketbased procurement, the required flexibility is secured and allocated to individual DERs. These facilities subsequently receive control signals and adjust demand accordingly to mitigate congestion at distribution substations. Under this framework, securing sufficient controllable demand capacity is essential. However, large charging demand from DERs significantly alters power flow, which may lead to severe voltage drops depending on the spatial allocation of

DERs within the feeder. Therefore, it is necessary to assess the voltage impact associated with

DER control in advance when applying this operational approach. This study evaluates the impact of DER-induced demand increase on voltage profiles in a 1-bank, 4-feeder distribution system model based on an actual network with high PV penetration. DER installation cases were examined for locations at the feeder root and at 3 km from the root to analyse spatial sensitivity. Furthermore, fixed power factor–based reactive power injection during charging was introduced as a voltage mitigation measure. The results demonstrate the effectiveness of

DER demand increase for congestion relief and clarify the conditions under which fixed power factor control can suppress voltage deviations, thereby enabling more flexible DER-based congestion management.