DSO-TSO cooperation issues and solutions for distribution grid congestion management

The role of DSOs is evolving due to the increasing penetration of intermittent and distributed energy resources in the distribution system. On the one hand, TSOs are accessing flexibility resources connected to the distribution grid. On the other hand, DSOs are actively managing distribution grid congestion, moving away from the conventional fit and forget approach. As a result, the need for DSO-TSO cooperation has become increasingly important. In this study, we first discuss market and grid operation issues related to different system states and the corresponding congestion management approaches, in the context of the European electricity market design and regulation. Second, we discuss viable solutions that are inspired by inter-TSO cooperation solutions as well as solutions that are being adopted by DSOs. Our findings show that the issues are rather similar both at transmission and distribution level; however, the need for cooperation and the solutions will depend on where structural congestion will occur and which borders will be managed. We also note that cooperation between DSOs as well as between DSOs and microgrids could become more important with the development of local energy markets in the long term.