This discussion paper identifies and consolidates the lessons learned from international projects, use cases, and best practices on TSO-DSO interaction. The results have been obtained from projects that are still in their early phases based on their preliminary findings as well as those that have reached their dissemination stages. Furthermore, this work aims to present a global view of developments of TSO-DSO interaction based on collaboration from stakeholders within the ISGAN community, as well as additional collaboration partners (TSOs, DSOs, project leaders, etc).

The main target audience is focused toward stakeholders who are familiar with the topic and will provide them with an overview and reference towards projects such that the lessons learned can be considered within future projects. The video provides a high-level overview which encapsulates the main findings, while this report forms a supplementary consolidation of the results in order to provide additional information in more detail.

Power systems around the world are faced with a wide range of challenges in order to realize the objective to integrate an increased amount of renewable energy sources in the modern electricity grids. The consequences affect the daily operation and longterm planning of transmission and distribution systems, and the network owners and operator’s ability to ensure continuous, reliable and high quality of supply to the customers. The needs of each actor within the electrical supply chain provide drivers for revision of current practices and promotes future adaptions of functional components and systems, economic and regulatory areas.
This document provides insights in the work of ISGAN Annex 6, in form of key messages consolidated from the views of the focus areas

• Technology Trends and Deployment
• Expansion Planning and Market Analysis
• System Operation and Security
• Transmission and Distribution System Interaction

micro and MEGA represent two trends which largely influence the decisions and the evolutionary process of power grids.

The trends are both aimed at enabling very high penetration of renewable energy sources
in the electric power system, from two perspectives:

• micro focuses on local solutions, while
• MEGA focuses on system or even intra-system wide solutions

ISGAN Annex 6 has dedicated an activity to study the micro and the MEGA trends, with the objective to present a critical assessment of these trends, based on the questions:

• Does one trend outcompete the other?
• Does increased investments from one perspective increase the need for investments
  from the other perspective?
• To what extent can one perspective benefit from the other perspective?

The intention is not to proclaim one solution being superior to another, rather to provide well
informed insights to the needs of considering both perspectives during the planning
and decision-making process for the sustainable development of the wider energy
system.

The outcome of this activity are communicated through publications, presentations and workshops, with contributions from a large number of parties:

• In the Policy Brief: micro vs MEGA – trends in power system development, the condensed knowledge from this activity was published for the 11th Clean Energy Ministerial hosted by Saudi Arabia, September 2020

• In the Discussion Paper (DOI: 10.13140/RG.2.2.11569.61287), the full report is provided from this activity, including detailed insights into the micro & MEGA trends and their perspectives together with experiences from around the World.

• Workshop and meeting in Montreux
  A highly successful event, gathering a total of 30 participants, with presentations (available here) from Italy, India, Spain, Belgium, France, Germany, Norway and Sweden.
  The participants at these two meeting days have shown a high level of engagement and it has been highly valuable to learn from each other. In short, we can conclude that these meetings were very productive and successful in gathering a large amount of knowledge.