Research issues in planning methodologies
The planning methodology to be used for this long-term 2050 horizon leads to a paradigm shift. A challenging top-down approach is needed, which requires R&D methodology to take into account several irreversible trends:
Independent planning for generation and transmission
Before the 1980s, considerable research was focused on the study of integrated resource or composite expansion planning. Generation and transmission planning were generally managed by large integrated utilities following long-term, detailed national energy policies and promoting large centralised power plants. In the 1990s, a market-based approach to operating and planning the electricity system was introduced in the USA and then in Europe. Unbundling of generation and transmission activities implies that generation and transmission planning are now performed independently: transmission planning uses assumed generation planning, since competing generators are no longer willing to disclose their long-term strategic plans.
Development of renewable electricity generation
Since the late 1990s, European energy policies have been progressively promoting renewable energy sources. This has produced small and decentralised electricity generation sites, which are usually variable. Moreover, many of the generation sites are distanced from consumption regions, as, for instance, on-shore or off-shore wind farms, thus requiring network expansion to transport electric power to where it is needed.
A growing need to implement new infrastructures
Transmission development takes more time than the installation of renewable energy generation units in particular. This can provoke unacceptable system behaviours, such as drops in voltage or sudden disturbances originating from either the generation or the consumption side.
This has required TSOs to install more underground cables and to construct new Direct Current (DC) links in order to fulfil their task of upgrading or replacing existing Alternating Current (AC) lines. TSOs will need to implement an increasing combination of such technological solutions, which, in turn, makes the pan-European system increasingly more complex to design and operate.
New and evolving technology background
Finally, power electronics will be increasingly deployed at generation level (Doubly Fed Induction Generator (DFIG) for wind turbines, full electronic inverters for PV) and within the grid (Flexible Alternating Current Transmission System (FACTS) devices, Direct Current (DC) links, and Direct Current (DC) networks) to allow increasingly real-time control of the power flow. This would lower today’s pan-European system inertia, making the system even more sensitive to any type of disturbance. The expected dynamics of such a power system will have to be considered very early in the planning process, although this is a relatively unexplored area.
At the same time, novel technology solutions downstream of the Transmission Network will open routes for improved network design and operations. For instance:
- The deployment of Smart Metering will give TSOs/DSOs more information to plan/operate the grid based on improved knowledge (with respect to space and time) of electricity distribution and local consumption.
- Large-scale, demand-side management approaches could be developed provided that the costs of the required infrastructure are affordable and regulatory regimes allow for novel balancing and settlement approaches.
- The progress in ICT, high computational power and large bandwidth communication networks at affordable cost will favour advanced monitoring and control of very large power systems following the current technology trends (such as High Voltage Direct Current (HVDC) lines using Voltage Source Control, Modular Multilevel Converters, Dynamic Line Rating).
- Electricity storage could help generators to manage variable generation and load as well as arbitraging for a better economic valorisation of renewable electricity.
e-Highway2050: A new planning approach
Overall, the planning for 2050 requires implementing a new planning approach which considers both the size of the system and the long-term horizon. In order to cope with these challenges, very different possible future scenarios must be taken into account. Following the results delivered by the Ten-Year Network Development Plan and by projects focusing on the mid-term view, e-Highway2050 is focusing on a long-term 2050 horizon leading to a paradigm shift (see figure). Such a study, dealing with a very high level of combinatorial aspects, has never been carried out before.