Investment focuses on improving transmission networks

Paul Boughton

Around the world, from Europe to China and the USA, billions of Euros is being invested in improving transmission networks. Sean Ottewell reports.

Norwegian system operator Statnett and its Danish counterpart have signed contracts with cable suppliers for the fourth interconnector between Norway and Denmark - known as Skagerrak 4. The contracts have a total value of EUR127 million and launch the construction phase of the project (Fig. 1).

"These contracts are the first major contracts to be signed at the Skagerrak 4 project, and therefore mark a significant milestone for the project," says project manager Arve Strandem at Statnett. Skagerrak 4 is planned to be completed by the end of 2014.

The HVDC cable will be supplied by the cable manufacturers Nexans and Prysmian. Nexans will provide a 137km offshore cable and 12km onshore cable in Norway, while Prysmian will provide the 91km onshore cable to be installed in Denmark. Prysmian's contract amounts to about EUR40 million, whilst Nexans' contract is worth approximately EUR87 million.

The companies say that the interconnector will facilitate more renewable energy production in both countries and benefit consumers and the industry through more stable power prices and increased security of power supply.

Currently there are three DC connections between Norway and Denmark, Skagerrak 1-3, with a total capacity of 1000 MW. The new Skagerrak 4 interconnection will have a capacity of 700MW, which will increase the capacity by 70 per cent to 1700MW. The total construction budget is around NOK 3 billion (EUR380 million), also comprising two converter stations at Tjele in Viborg and Kristiansand in Norway. Costs are shared between the two companies.

In a separate development, the NorNed cable has successfully joined the interregional market coupling between Central-Western-Europe (CWE) and the Nordic countries.

The cable couples France, Belgium, the Netherlands, Luxemburg and Germany in the Central-West on one side, and Norway, Sweden, Finland, Estonia and Denmark on the other. The inclusion of the NorNed with the undersea DC-link between Norway and the Netherlands is the final milestone of the interim tight volume coupling (ITVC) project between the two regional markets.

Together, CWE and ITVC couple price and volume, integrating a day-ahead market of more than 1800 TWh of power production and cover approximately 60 per cent of electricity consumption in Europe.

Now the transmission system operators and power exchanges involved in the scheme are looking towards further pan-European price coupling.

Meanwhile Swiss company ABB is helping to strengthen the power transmission network in Ukraine, following an order worth US$20 million (EUR14 million) from NPC Ukrenergo, Ukraine's national power grid operator. The order covers supply of 44 sets of SF6 (sulphur-hexafluoride gas) circuit breakers rated at 800kV. They will be installed in five 750kV transmission substations around the country (Fig. 2).

These modern circuit breakers will replace outdated air blast-type circuit breakers that have been in operation for nearly four decades. ABB will supply the equipment and provide technical training. The circuit breakers will be replaced in four phases, starting this year and ending in 2014.

ABB's ultra-high voltage 800kV SF6 circuit breaker has innovative features that include a single operating mechanism per pole, replacing the two found in conventional 800kV breakers. This provides greater reliability, reduced initial costs and considerable reductions in maintenance costs. The shift from air blast technology also eliminates the need for air compression facilities.

The company will also supply control cabinets with bay control devices for the circuit breakers, along with an on-line condition monitoring system built on ABB's substation automation technology.

Ukraine is one of a few countries in the world with a 750 kV network. This project is part of the country's efforts to modernise and upgrade its power transmission network, which includes the refurbishment of 220 kV, 330kV and 750kV substations. In 2008, the country received a US$200 million (EUR143 million) loan from the International Bank for Reconstruction and Development to help fund the project.

Chinese transmission

ABB is also busy in China, where China Southern Power Grid has placed a US$63 million (EUR45 million) order with it for the installation and commission of an 800 kV ultrahigh-voltage direct current (UHVDC) transformer for a converter station that will form part of the Nuozhadu-Guangdong transmission system.

China Southern Power Grid is one of two leading state-owned utilities in China responsible for building and operating the power grid in the southern part of the country.

The 800kV UHVDC transformer is a key component of ultrahigh-voltage power links that deliver large amounts of electricity over long distances. There are many challenges involved in building such transformers - for instance, increasing the technical specifications of the transformer's insulation, and redesigning critical components such as bushings.

UHVDC technology enables more efficient use of renewable energy sources, reduces dependency on fossil fuels and helps cut carbon dioxide emissions. ABB says it is particularly suitable for large countries like China, where the centres of power consumption are often far from power sources.

Also in China, the world's first 660kV direct current power transmission system has begun to supply energy from the country's northwest Ningxia Hui autonomous region to the eastern Shandong province.

The US$1.58 billion (EUR1.13 billion) project is part of China's west-east power transmission programme.

The cable system has a current-carrying capacity of 4 million kW of electricity travelling over a distance of 1333km through five provinces and regions.

To generate the same amount of electricity, about 13 million tonnes of coals would be needed along with 650,000 20tonne delivery trucks.

China's coal resources are mainly based in the west and north, which are economically underdeveloped compared with the east. The west-east power transmission programme started in 2000.

The country's State Grid Corporation plans to build six cable systems, including three west-east facilities and three north-south systems, between 2011 and 2015.

US integration

Prairie Wind Transmission, a joint venture between Westar Energy and Electric Transmission America, has filed a siting permit application with the Kansas Corporation Commission (KCC) to request permission to build a new, double circuit 345 kV transmission line. The proposed line would go from Westar Energy's Wichita 345 kV substation, about one mile northeast of Colwich, to a new substation just east of Medicine Lodge, Kansas, and then south to the Kansas-Oklahoma border. Oklahoma Gas and Electric (OGE) will continue the line from the Kansas-Oklahoma border to its Woodward substation, about ten miles south of Woodward, Oklahoma.

The project is part of the Y-Plan that the Southwest Power Pool approved last year. This high-capacity transmission line will improve the regional electric grid by better integrating the east and west regions and facilitating the addition of renewable generation to the electric grid.

Late last year and early this year, Prairie Wind Transmission conducted six open houses to exchange information with landowners near several routes being considered for the transmission line. About 294 completed questionnaires were received from landowners and area residents who attended open houses or contacted Prairie Wind Transmission regarding the line.

With the KCC's approval expected in late June 2011, Prairie Wind transmission will begin working with landowners to acquire easements in the July-August 2011 time frame. Once easements have been acquired, construction is estimated to begin in the summer of 2012. The company anticipates the project will be complete at the end of 2014. Prairie Wind currently estimates that it will cost about US$225 million (EUR161 million).

Major UK electricity distribution business changes hands

US company PPL is buying Central Networks' electricity distribution business from EON for £3.5 billion. Based in central England, this is the second-largest such business in the UK.

Central Networks' regulated distribution operations, which serve five million customers in the midlands area of England, are conducted through Central Networks East and Central Networks West. PPL currently owns Western Power Distribution, which provides regulated distribution services to 2.6 million customers in England and Wales through WPD South West and WPD South Wales. The WPD and Central Networks service territories are contiguous and PPL says it is expecting significant synergies from the combined operations.

After completing the acquisition, PPL will own and operate the largest network of electricity delivery companies in the UK in terms of regulated asset value, at a combined £4.9 billion.

"Opportunities as compelling as this do not come along very often. The UK provides a progressive regulatory environment; Central Networks is adjacent to our existing, high-performing operations; and there are very real opportunities for retainable synergies that further enhance what already is a compelling transaction," said James H Miller, PPL chairman, president and ceo.

Central Networks is responsible for the operation of about 83,000 miles of lines in an area comprising central England, including the cities of Birmingham and Nottingham. WPD operates about 52,000 miles of lines in South West England and South Wales, including the cities of Bristol and Cardiff

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