DSO-TSO interaction is defined as the collaboration between the two operator levels in the power transmission system: The transmission system operator (TSO) and distribution system operator (DSO). The interaction and coordination between the system operators may be divided into the following domains: (1) The market framework, used for acquiring reserves of system services, (2) Operation, to ensure security of supply, (3) Grid planning and (4) Data sharing and handling according to regulations. The current status and framework of DSO-TSO interactions was reviewed early on in CINELDI [1]. According to this report, the European energy portfolio is expected to change significantly, such as renewable energy sources increasing from 21 % in 2010 to 44 % by 2030. Phasing out of nuclear power production is also expected, as well as structural changes, such as an increase in number of cables between the Nordic and continental European power systems. These and other changes are expected to change the DSO-TSO collaboration framework. Development of regulations happens for instance through Network Codes (NCs) which are developed at European level by ENTSO-E.

Coordination schemes for DSO-TSO interaction was reviewed [2], which are necessary for procurement and activation of ancillary services: a centralized market which is operated by the TSO or DSO only, by some combined balancing responsibilities or by a third party operator. The centralized market scheme is most in line with current regulations.

The NC on electricity emergency and restoration (NC ER) is central for DSO-TSO interaction in restoration and defense actions. A CINELDI report [3] reviewed the NC ER and what consequences the implementation of this NC will have on distribution system operations.

The effect of the new regulations on the balancing market was also studied. When adapting regulations into practice, the market design is crucial for its success. Bobinaite et al. [4] aimed at an economically efficient market design for system balancing market within the Web-of-Cells architecture, and found that a competitive allocation process with allocation time close to real-time is important, especially with increased RES penetration.

[1]          A. Z. Morch and H. Sæle, “DSO-TSO Interaction Overview,” SINTEF Energy Research, Trondheim, 2018.
[2]          A. Z. Morch, H. Sæle, D. Siface, H. Gerard, and I. Kockar, “Market architecture for TSO-DSO interaction in the context of European regulation,” in 2019 16th International Conference on the European Energy Market (EEM), Ljubljana, Slovenia, Sep. 2019, pp. 1–5. doi: 10.1109/EEM.2019.8916314.
[3]          A. Z. Morch, “Regulatory framework in restoration and defence actions,” SINTEF Energy Research, Trondheim, 2021.
[4]          V. Bobinaite, A. Obushevs, I. Oleinikova, and A. Morch, “Economically Efficient Design of Market for System Services under the Web-of-Cells Architecture,” Energies, vol. 11, no. 4, Art. no. 4, Apr. 2018, doi: 10.3390/en11040729.