Interconnectors improve integration

Paul Boughton

Around the world, cross-border interconnector technology is helping countries to even out their electricity usage and improve efficiency. Sean Ottewell reports.

In February the first cross-border power interconnection between Bangladesh and India was completed. The 500MW, back-to-back high-voltage direct current (HVDC) system will power up to 180,000 homes and is capable of future expansion to 1000 MW (Fig. 1).

The initial contract was awarded in March 2011 by Power Grid Company of Bangladesh (PGCB) to Siemens. The first 175MW of power flowed from India to Bangladesh in September last year. This is the first such electricity grid interconnection among South Asian Association for Regional Cooperation (SAARC) countries.

The system links India's eastern electrical grid to Bangladesh's western grid. The HVDC station in Bangladesh is connected to the country's existing 230 kV grid. A new 400 kV alternating current high-voltage overhead line provides the cross-border connection to the 400 kV substation in India. This project also enables Bangladesh's power generation from less inefficient diesel power plants to be reduced, helping the country to lower emission levels.

Converter stations

Siemens has also completed the EstLink 2 project, an HVDC link consisting of converter stations in Anttila, Finland, and Püssi, Estonia. Power is now transmitted by the customers, Fingrid - the transmission system operator in Finland, and the Estonian transmission system operator Elering.

The new link increases the power transmission capacity between the countries by a factor of three - increasing it from 350MW to 1000MW.

This project plays an important role in the integration of energy markets between Baltic and Scandinavian countries, opening up access to renewable energy sources and generating revenue resources.

It is also a significant step towards meeting the goals of the EU's Baltic energy market interconnection plan (BEMIP) which aims to integrate Lithuania, Latvia and Estonia with EU transmission networks and energy markets.

Overall the EstLink 2 project spans 170km. Power is transmitted over about 14km of overhead line in Finland, about 145km of submarine cable laid on the bottom of the Gulf of Finland, and approximately 11km of underground land cable in Estonia.

Monopolar connection

Siemens was responsible for designing the HVDC system as a monopolar connection with metallic return conductor. This turnkey project included delivering, installing and commissioning of the complete HVDC converter stations, excluding the overhead line and power cable part in between the stations. The total value of the converter station turnkey project was EUR100 million, about a third of the total EstLink2 interconnection budget.

In the UK, National Grid Nemo Link has been granted planning permission from Thanet and Dover District Councils to go ahead with developments at the former Richborough power station site in Kent.

These include plans for an electricity substation, a converter station and underground cables between Richborough and Pegwell Bay on the English channel coast.

By 2018 Nemo hopes to have in place the first electricity link between the UK and Belgium. Running 130km from Richborough to Zeebrugge, the subsea cables would allow 1000MW of electricity to be traded between the two countries.

Mark Pearce, project director for National Grid said: "Interconnectors will have an important role in diversifying the sources of electricity for this country and helping to keep our supplies secure. It will also help create a competitive European market."

Integrated power market

In a separate move, UK energy minister Ed Davey has claimed that the only way Britain can benefit from US-style low energy prices is by creating a totally integrated power market across Europe.

In an interview with UK newspaper The Independent, Davey said there was an urgent need to build a giant network of electricity interconnectors across Europe, allowing vast amounts of energy to be moved between countries, driving down prices.

"Literally in the last three or four years, there has been a complete change in the differential between the North American price for gas and energy and the EU price for gas and energy. That represents a strategic change in the terms of trade and is very significant. The EU needs to respond to this very quickly," he said.

He called on the EU to do much more to fast-track plans for a continent-wide energy network, saying British and European manufacturers risked being left behind by US rivals which were exploiting cheap energy from its shale gas boom to improve productivity.

"We need much better grid interconnectors around Europe to enable energy to flow across the EU. Connect the UK with mainland Europe and different parts of the periphery of Europe with central Europe. We need Eastern and Central Europe to be better connected with Germany and France and we need the Iberian peninsula to be better connected through France," he added.

EU funding for ultraconductive copper wire project

A consortium of 14 companies and universities has signed a EUR3.3 million funding contract to bring ultraconductive copper, a material that conducts electricity better than any known electrical conductor, within three years to a level where pilot manufacturing can be planned.

The project, known as Ultrawire, is part funded through the European Commission's FP7 programme and partly by the consortium members.

These include Cambridge University, KME Germany, University of Aalto at Helsinki, AGH Krakow University of Science and Technology, Peugeot Citroen Automobiles, Wieland-Werke, the European Copper Institute (ECI) and Nexans France.

"We are exploiting forefront European carbon manufacturing technology and transferring exciting new materials into industry," says Dr Krzysztof Koziol, head of the electric carbon nanomaterials research group in the department of materials science and metallurgy at the University of Cambridge. Koziol is the project coordinator and the leading contact with the EC for the Ultrawire project.

"The copper industry's participation in this project reflects the importance the industry places on improving the sustainability of its products through increased resource efficiency," says John Schonenberger, chief executive of the ECI. "The EU has extremely ambitious carbon dioxide emission reduction targets for 2050 and the necessary transition toward electricity, as the primary source of energy, will require significant quantities of highly-efficient conductor materials.

"While this technology is in the very early stages of development, with many significant hurdles to cross, ultraconductive copper would bring about a step change in the end-use performance obtainable from one tonne of copper,' he added.

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