Transcontinental and global power grids

Background and context

The European power transmission grid is on the critical path to meet the EU’s climate change and energy policy objectives. The main challenge is the power system integration of very large amounts of variable renewable energy sources, especially wind and also solar, while keeping overall system reliability at acceptable levels, in a liberalised context. To this scope, a more flexible, yet robust, transmission grid is needed.

The best locations for the generation of renewable electricity are not uniformly distributed across the continent, and are often in places where connections to the electricity network are weak. The energy production from renewable sources also greatly depends on weather conditions. To fully utilise these resources, the power grid must be enhanced to allow electricity to be transported to the main centres of demand and storage. This may drive the evolution of the transmission grid towards a super grid. That is a higher transfer capacity system designed to transport large amounts of electricity over long distances.

HVDC systems will play an important role in connecting high-volume renewable energy generated in remote areas (e.g. offshore) into the main grid. Due to their lower losses and smaller environmental impact, HVDC lines are considered the most suitable technology for this task. HVDC links can play a role towards the potential realisation of transnational and transcontinental (mixed HVAC and HVDC) power grids. Europe has been at the forefront of HVDC research, development and deployment since the beginning of large-scale pilot projects in 1950s-1960s. All the major companies in the field that innovated and set the standards are located in Europe. The same companies built or extensively contributed to projects worldwide.All the HVDC projects deployed in Europe are “unique”, that is all the equipment is sized to that specific project; no two projects are alike. All the HVDC projects in Europe (with one exception) are point-to-point with specific parameters meeting the local conditions (grid connection, voltage levels, capacity). Other countries and continents worldwide have lately emerged as growing markets for HVDC technology. In particular, China, although lacking a proper (interconnected) HVDC grid, has built in the last two decades more than 30 HVDC lines. European HVDC equipment producers have started and built the first projects but through technology transfers China is able now to produce almost the entire set of equipment and to manage also the planning and designing phases. Many of these HVDC links are built (or are in building phase) as standardized systems in terms of parameters (nine systems of 500 kV / 3000 MW, 11 systems of 800 kV / 6400 MW).

Our role

Against this background, we assess building blocks and progress to speed up the development and modernisation of the European electricity grids. More in detail, we are conducting targeted research on:

  • technological developments towards higher transfer capacity architectures
  • monitoring the challenges for redesigning the trans-European electricity networks.

2015 - HVDC Submarine Power Cables in the World

This report provides an extensive study on the availability of the technologies required for the realisation of a HVDC interconnection between the European and North American Alternating Current (AC) transmission grids.

High Voltage Direct Current (HVDC) interconnections started to spread across land and underwater becoming longer and more powerful. The advance of this technology makes them the prime option for bulk power transmission in future. While on land the length can reach thousands of kilometres underwater they measure less than 600 km. The constraints but also the future developments must be addressed in order to assess the perspectives of this technology.
JRC is performing a study to identify and analyse the technical and geopolitical challenges for building an offshore electricity transmission interconnection between Europe and North America.
The report revises the main submarine power cables in the world along with their characteristics. Special attention is given to the installation of HVDC submarine cables. Techniques for laying a cable are discussed. Also issues such as protection measures and maintenance aspects are dealt with. The operation of HVDC submarine cable is treated as well. Reliability and accident risk issues are discussed in a dedicated paragraph as well as environmental aspects.

2014 - It's a Bird, It's a Plane, It's a...Supergrid!

This article discusses the emerging challenges facing the European transmission grid as it contributes to meeting the EU's energy and climate change policy goals. We focus on the European ultra-high-voltage system, which is already considered to be a “smart” system but is expected to evolve toward architectures offering higher transfer capacities (a so-called “supergrid”).

We address the challenges of making power distribution systems smarter only insofar as transmission-distribution interfaces are concerned, in the course of illustrating the tensions and complementarities within the smart grid and supergrid concepts.

In this light, the article presents the main policy objectives and visions for electricity in the European Union, key figures and trends relating to the European energy and electricity systems in a worldwide context, and technological options and design challenges for the pan-European transmission grid. The article ends by summarizing various needs and potential solutions for the EU transmission grid in view of its long-term evolution.

2014 - Electricity exchanges with North Africa at 2030: The European and the Italian approaches

This chapter provides a first preliminary analysis on the effect of African solar energy import on the Italian system at 2030. In particular, the aim is to provide a first preliminary answer to questions like:

- what flow will prevail in Italy at 2030 (wind from the Northern border or solar from the Southern border);

- how could the market prices be modified as the effect of Renewable Energy Sources (RES) import from North and from South.

The scenario analyses presented in this study are the result of collaboration between the Joint Research Centre of the European Commission and Ricerca sul Sistema Energetico, which developed, respectively, a pan-European approach and a detailed model of the Italian system.

 

2013 - Effects of North-African electricity import on the European and the Italian power systems: a techno-economic analysis

This paper, based on the combination of two methodologies, presents a first techno-economic analysis of the effects of electricity imports from North Africa on the European and the Italian power systems in 2030.

Several European initiatives consider the electrical integration of the Euro-Mediterranean region a key priority for meeting future European Union (EU) energy policy goals. Ambitious plans include the development of Renewable Energy Sources (RES) in the region as well as transmission interconnectors between the two shores of the Mediterranean Sea. The success of such initiatives, in addition to several technoeconomic, political, environmental, regulatory and financial obstacles, depends on the ability of the European electricity network to suitably accommodate large electricity imports from North Africa.

Within a common framework, the adopted approach has proved its feasibility with coherent results showing a decrease in electricity prices in Europe. The European study shows how net electricity exchanges tend to follow the direction from South to North. The impact of North-African electricity on the Italian system is relevant. Also, Italy’s potential of becoming a Mediterranean electricity hub is emphasised. National internal grid congestion results to be a crucial issue for the Euro-Mediterranean electrical integration.

2012 - Behaviour of Multi-Terminal Grid Topologies in Renewable Energy Systems Under Multiple Loads

This paper identifies and analyses by means of MATLAB or NEPLAN models transient responses of four representative Multi Terminal Grids topologies for renewable energy systems.

Decarbonization policies adopted worldwide are leading to a steadily increasing deployment of renewable energy sources (RES). In Europe, for example, a multitude of wind farms is built at (predominantly) onshore and (increasingly) offshore sites. The connection of offshore wind farms is expected to promote the realization of Multi Terminal Grids (MTG), which include High Voltage DC (HVDC) transmission systems requiring high voltage inverters. Due to the semiconductor components used in the inverter systems, voltage and current fluctuations occur before and after the inverters, producing harmonics, voltage oscillations and power loss in the transmission system.

The study escalates the complexity of the simulation starting from a point-to-point HVDC connection up to the interconnection of five (5) inverter terminals. In order to address all the possible connection options the authors examine different topologies for grid having more than three points. The different responses of the network configurations under study are analyzed and compared. Simulation results are then validated with hardware-in-the-loop experiments in the Smart Grid Simulation Centre of the European Commission's Institute for Energy and Transport (IET).

2011 - A European supergrid for renewable energy: local impacts and far-reaching challenges

This paper assesses the impact of extensive deployment of indigenous and external renewable energy sources on a local electricity system (Sardinia Island) and discusses the main challenges faced by the European power grids in integrating high shares of renewable-based generation technologies. It presents the 2030 scenarios for the Sardinian power system and the results of steady-state analyses in extreme (renewable) generation and consumption conditions.

These results are eventually combined with the assessment of key technology development trends to explain how this can affect the development of a European supergrid.

In general, the article stresses that rendering the bulk-power system capable of accommodating high renewable energy penetration not only requires reinforcing the electricity highways but also demands carefully planning the architecture of and the interface with regional power systems.

2011 - Evolutions and Challenges towards a Potential Pan-European HVAC/HVDC SuperGrid

This paper investigates the role of HVDC towards the development of the future transmission system in Europe: particular attention is paid to current evolutions and challenges ahead of the potential realisation of a pan-European (mixed HVAC and HVDC) SuperGrid in a long term view, also in line with the recently issued European Commission’s Energy Infrastructure Package.

In presence of several issues more frequently constraining the realisation of new High Voltage Alternating Current (HVAC) overhead infrastructures, the need for evolution in the design and operation of transmission system towards a re-engineering process emerges in Europe. Among the different measures to support such shift, there may crucially be the use of High Voltage Direct Current (HVDC) technologies for advanced power transmission.

After introducing key technical, economic and environmental characteristics of HVDC technologies, this paper reports some specific long-distance HVDC applications for bulk power transmission in extra-European systems towards potential SuperGrid implementations in Europe. The developments at the eastern and southern edges of the European system as well as across the North Seas, the Baltic Sea and the continental network are then specifically investigated in their evolution stages as potential building blocks of a long term pan-European SuperGrid.

 

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