Transmission and Distribution – ONE GRID

Since 1921, for more than 105 years, CIGRE – for power system expertise has supported the development and reliable operation of electricity systems worldwide by providing a truly global, neutral platform for technical exchange, collaboration, and engineering excellence. Across generations of engineers and through profound technological, economic, and societal change, CIGRE has remained committed to advancing knowledge and fostering cooperation in the power sector.

Throughout this long history of continuous transformation, one fundamental principle has remained unchanged: the electricity system is one grid, governed by common physical laws, shared technical constraints, and collective responsibilities. Regardless of voltage level, geography, or regulatory framework, all parts of the system are intrinsically interconnected. Decisions taken in one part of the grid inevitably affect the performance and stability of the whole. It is essential to emphasize that One Grid reflects the complementary roles of transmission and distribution as equal partners, whose close cooperation is indispensable for the performance and evolution of the overall power system.

Today, this system is being reshaped at an unprecedented pace. Distribution networks, once designed primarily for unidirectional power flows and passive operation, are undergoing a profound transformation. They are becoming active, digital, and increasingly complex systems, integrating large volumes of distributed energy resources, electric mobility, energy storage, flexible demand, and advanced power electronic interfaces. Digitalisation, automation, and real-time data are fundamentally changing how networks are planned, operated, and maintained.

Consequently, the traditional conceptual separation between transmission and distribution is no longer sufficient to address the challenges of modern power systems. Power flows are becoming more dynamic and less predictable, while system inertia, fault levels, and voltage control characteristics are changing across all voltage levels. In this new context, local actions can have system-wide impacts, and system-level phenomena increasingly manifest themselves at the distribution level.

Security of supply, system resilience, power quality, and overall efficiency can therefore only be ensured through a whole-system approach. Transmission and distribution are not competing domains or isolated responsibilities; they are complementary layers of a single infrastructure serving society’s growing dependence on electricity. Their close coordination is essential for the successful electrification of transport, heating, and industry, and for achieving ambitious decarbonisation and climate objectives.

This evolution places Distribution System Operators, distribution experts, and manufacturers at the very heart of the energy transition. Their operational experience, technological innovation, and deep understanding of real-world constraints are critical to maintaining system performance while enabling change. Planning methodologies, protection concepts, control strategies, and asset management practices must evolve in a coordinated manner across transmission and distribution boundaries.

By engaging actively in CIGRE’s unique Working Group structure, which today comprises more than 300 active Working Groups worldwide, distribution stakeholders can both benefit from and contribute to a depth of collective expertise that is unmatched in the power sector. This collaborative framework enables practical experience to be shared across regions, technologies, and voltage levels, translating research and innovation into robust, implementable solutions. Crucially, it ensures that distribution perspectives are fully embedded in system-level analyses, recommendations, and best practices.

After 105 years, CIGRE’s mission is more relevant than ever. As power systems become more distributed, more digital, and more dynamic, the need for shared understanding, common language, and close collaboration across all parts of the grid continues to grow. Addressing future challenges will require engineers and experts from transmission and distribution to work together more closely than ever before.

We therefore invite the distribution community to engage actively in CIGRE’s work, to contribute their expertise, and to help shape the future of power systems, with the forthcoming Paris Session in August providing an ideal platform to join. The energy transition will succeed only if the grid of tomorrow is developed, operated, and governed as one integrated system—transmission and distribution, working together, as one grid.

Konstantin O. Papailiou
President of CIGRE