HVDC Electricity Transmission Lines Enabling Single EU Energy Market

by Kristen Wright, Contributing Editor


The snowcapped Pyrenees tower in the distance near the Baixas converter station in southern France. The HVDC Baixas-Santa Llogaia transmission line runs underground for its 64.5-kilometer-long entirety, including an 8.5-kilometer-long tunnel bored through the Pyrenees. (photo by Kristin Wright)

High-voltage direct current (HVDC) electricity transmission is becoming a key enabler of the emerging single energy market of 34 interconnected European countries.

To spur market integration, the European Commission has created a list of “Projects of Common Interest” (PCIs). The PCI list is updated every two years, and the next update is expected at the end of 2015.

Of the 248 PCIs that were eligible for EU funding from 2013, 137 involved electricity, 52 of which are interconnections. By 2020, three-fourths of the EU’s infrastructure PCIs should be completed.

According to the European Commission, a PCI should:

  • Significantly affect the energy markets of at least two EU countries, such as by contributing to the integration of their networks;
  • Increase energy market competition by offering alternatives to consumers;
  • Enhance the EU’s security of supply by allowing countries to receive energy from more sources; and
  • Contribute to the EU’s energy and climate goals, for example, by integrating renewable energy into the grid.

Projects that make the PCI list are eligible for numerous benefits, including:

  • Accelerated planning and permit-granting procedures, including a three-and-a-half-year time limit for granting permits;
  • One national permitting authority;
  • Lower administrative costs for project promoters and authorities–the result of streamlining environmental assessments;
  • More transparency and public participation (projects must conduct public consultations, create information manuals, etc.);
  • More visibility for investors; and
  • The possibility of financial support–5.35 billion euros ($6.05B US) total from 2014 to 2020–under the Connecting Europe Facility (CEF).

In 2014, the CEF allocated 647 million euros to PCIs, and 34 proposals won grants for studies or works. Most projects on the list involve electricity and gas transmission, but projects that involve electricity storage, underground gas storage and LNG terminals also made the list. The Baltic region won most of the funding for projects that address urgent security of supply needs.

In 2015, PCIs are eligible for 650 million euros in grants.

Under the first CEF energy call for proposals in 2015, 159 million euros were allocated to PCIs, and 20 proposals were selected to receive grants for studies or works: 11 gas projects and nine electricity projects. Most of those projects are in Central Eastern and Southeastern Europe, as well as the Baltic region. The second call for proposals in 2015 was published June 30 with a closing date of Oct. 14. The announcement will be made in February 2016.

A PCI Completed in 2015: Baixas-Santa Llogaia Interconnection

Some of the PCIs have been completed, including the Baixas-Santa Llogaia HVDC transmission line that doubled the electricity interconnection capacity between France and Spain to 2,800 MW. The line, the fifth interconnection linking France and Spain, went into commercial operation this summer.

“This link between France and Spain is a new connection,” said Yves Decoeur, an engineer with French electric grid operator Réseau de Transport d’Électricité (RTE). The line is the only DC connection between the countries, and the first connection since 1982.

Also notable, it is the longest underground HVDC cable in the world. The 64.5-kilometer-long line runs from a converter station in Baixas, France, near Perpignan in the south, through an 8.5-kilometer-long tunnel bored through the Pyrenees mountains and adjacent to a high-speed train line between Perpignan and Barcelona, to another converter station in Santa Llogaia in northern Spain.

The transmission line holds two other world records, too, Decoeur said. At 2,000 MW, the line holds the record for DC with voltage sourced converters (VSC) technology. It also is the record holder for voltage level for a cross-linked polyethylene (XLPE) cable in DC at 320 kV.

Baixas-Santa Llogaia Transmission Line Stats

Current System: DC

Technology: Voltage Source Converter

Rate Voltage: ±320 kV

Transport Capacity: 2,000 MW (2×1,000 MW)

Number of Circuits: 2 Independent Systems

Number of Electric Cables: 4 Cables (2 per connection)

Length in Spain: 31 km

Length in France: 33.5 km

Total tunnel length: 8.5 km

Cable technology: XLPE

The Baixas-Santa Llogaia HVDC transmission line qualified as a PCI because it enhances security of supply for residents of the Roussilon and Empordà regions in France and Spain, and it increases the economic attractiveness of both regions; it improves renewable energy integration; and it contributes to French, Spanish and European companies’ competitiveness.

“It’s a very important link also for Europe,” Decoeur said.

The transmission line helps ease what has been called one of Europe’s biggest electricity bottlenecks. And it contributes to achieving Europe’s 10 percent electricity interconnection target by 2020, meaning the goal for each EU member country is to be able to move at least 10 percent of its installed electricity production capacity across its borders. In February, the European Commission said 12 EU member states remain below the 10 percent interconnection goal: Cyprus, Estonia, Ireland, Italy, Lithuania, Latvia, Malta, Poland, Portugal, Romania, the U.K. and Spain.

But Spain has 30,000 MW of available renewable energy, and France has plenty of nuclear power to share. And because the neighboring countries boast different cultures and electricity consumption habits, their electricity supplies and demands tend to be symbiotic. In France, power consumption peaks around 1 and 7 p.m., but in Spain, it’s noon and 9 p.m., Decoeur said.

So when Spain has excess renewable energy during peak power consumption in France, the two 1,000-MW VSC converter stations in Baixas and Santa Llogaia can reverse the flow of power easily and quickly–in a record 150 milliseconds, according to Siemens AG, the German company that built the converter stations. Same goes for when France produces excess nuclear power, which is especially valuable to Spain during harsh winters.

“It depends completely on the opportunities in each country,” Decoeur said.

During the testing phase before the Baixas-Santa Llogaia line went into commercial operation, power flow changed directions seven or eight times on one particular day, Decoeur said.

The HVDC Plus technology from Siemens also provides the possibility of black start. In contrast to grid-commutated power converter technology, the system works with power transistors that can be switched off (IGBT); that enables the commutation processes in the power converter to run independently of the grid voltage.

The fast control and protective intervention capabilities of the power converters provide for high stability in the transmission system, which reduces grid faults and disturbances in the three-phase AC network. This increases supply reliability for utilities and their customers. The project also includes continuous reactive power compensation independent of the energy transmission in the RTE grid and Spanish grid, operated by Red Eléctrica de España (REE).

The beginnings. The French part of the Baixas-Santa Llogaia line launched in 2003, initially as a plan for an overhead line. But the more economical overhead option didn’t fly. Decoeur, who has been involved with the project since 2006, said there was a harsh public debate and very long discussions about the environmental impact of the line to the Pyrenees.

Arguments against the overhead transmission line grew so loud in France and Spain that the countries’ governments appealed to Brussels for an intervention. Former Italian Prime Minister and European Commissioner Mario Monti was named European coordinator for the project. In 2008, Monti recommended an underground solution.

Decoeur said the move helped sway public opinion about line. “From that point, we can say people were much quieter,” he said.

Lluis Pinós Jorba, an industrial engineer with REE and project director for the Spanish side of the line, said the process on the Spanish side was much the same. “In this case, with the underground solution, we don’t have problems,” Pinós said.

The Baixas-Santa Llogaia project became official in 2008 when the French and Spanish governments signed the Zaragoza agreement, which states the two countries would work together on the project.

A few months later, the Interconnexion Electrique France Espangne (Inelfe) was born. The joint company was created by RTE and REE to lead the studies, engineering and construction of the Baixas-Santa Llogaia transmission line. Decoeur serves as general manager of Inelfe, and Pinós is a member of the Inelfe Control Committee.

The components. The investment for the Baixas-Santa Llogaia transmission line was 700 million euros ($756 million), 225 million euros of which came as a European Commission grant, and 350 million euros of which came as a loan from the European Investment Bank. The remaining cost was split 50-50 between RTE and REE.

Converter hall of a converter station on the French side of the HVDC transmission link between France and Spain. (photo courtesy of Siemens)

More than 500 companies were involved in the construction of the transmission line.

In 2011, earth work began for the converter stations and tunnel through the Pyrenees. French construction company Eiffage and Madrid-based infrastructure company Dragados led the consortium to bore the tunnel. The two companies started in their respective countries and bored through the Pyrenees until they met in the middle. Actual construction for the converter stations started in January 2012 on the Spanish side and a bit later on the French side.

“The converter stations are very expensive,” Pinós said. For the DC line, he said, the HVDC converter stations ate up nearly half of the 350 million euro loan.

The French and Spanish converter stations are identical except for the converter hall designs, said project manager Volker Lehmann. The Santa Llogaia converter hall is a standard design, but the Baixas converter hall blends into the landscape. Both buildings house the power modules that convert AC to DC. Each station also has seven transformers, an air cooling system and two smaller buildings for the control equipment. The converter stations were completed in August 2014.

In addition to the cost of the converter stations, the underground DC line cost some 10 times more than an AC solution using an overhead line, Pinós said.

“Underground is always more expensive than an overhead line,” he said.

Civil works, including excavation of the trenches, began in 2012 and were led by Ferrovial and SAG Thépault. The underground line runs through two, 1.5-meter deep, parallel concrete trenches that are about 3 meters wide total, including the gap between them, according to Inelfe. The project required drilling 37 holes–22 in Spain, 15 in France–to avoid geographical obstacles, and nearly 100 workers.

The French side finished excavation in October 2013, and the Spanish side finished in July 2014, according to Inelfe. One day after excavation, workers filled the trenches after the cable pipes and concrete were laid. Prysmian Group laid two parallel DC cables in each trench.

Electrical tests on the Baixas-Santa Llogaia HVDC transmission line began in February 2015 and commercial operation commenced in summer.

The HVDC Market

Tim Dawidowsky, CEO of Siemens’ transmission solutions business, said a high portion of DC power exists in the European grid, and he expects even more as the European super grid forms. Dawidowsky said more cross-border transmission projects are expected throughout Europe, including links between Belgium and the U.K., Norway and Germany, Germany and Belgium, Germany and Denmark, and the first north-south corridor in Germany, UltraNet.

Experts predict the HVDC market to nearly double within five years from its current 2.5 billion euros. In addition, experts expect the number of global installments of HVDC systems to grow some 250 GW by 2020.

Kristen Wright is managing editor of PEI Journal, a publication of the Petroleum Equipment Institute. She previously was an editor of POWERGRID International for seven years.

Previous articleThe Irvine Smart Grid Demonstration Leads the Way to Modernizing California’s Electric Grid
Next articleIntegration Center of Excellence – the Competetive Advantage to an Agile Smart Grid
The Clarion Energy Content Team is made up of editors from various publications, including POWERGRID International, Power Engineering, Renewable Energy World, Hydro Review, Smart Energy International, and Power Engineering International. Contact the content lead for this publication at Jennifer.Runyon@ClarionEvents.com.

No posts to display