Home » APPENDIX » Appendix G


PowePower system operators have been cooperating for decades, mainly to maximise system reliability and quality of power supply, while optimising the use of primary energy and capacity resources. As a result, five regional zones have emerged in Europe:

  1. The synchronous zone of the Nordic countries;
  2. The synchronous zone of the UCTE countries;
  3. The synchronous zone of Great Britain;
  4. The synchronous zone of the island of Ireland (Republic of Ireland and Northern Ireland); and
  5. The Baltic Interconnected Power System.

The Synchronous Zone of the Nordic Countries


This synchronous zone comprises the power systems of Finland, Sweden, Norway and Eastern Denmark. The capacity of these power plants is around 90 GW and the annual electricity production is nearly 400 TWh, serving around 25 million people. The total primary control reserve is 1600 MW (operating reserve 600 MW and disturbance reserve 1000 MW). The transmission system operators (TSOs) of these countries have organised a cooperative body, NORDEL, whose primary objective is to create the conditions for, and to develop further, an efficient and harmonised Nordic electricity market. This synchronous zone is interconnected by DC lines to Poland, Germany and Russia.

The Synchronous Zone of the UCTE Countries


The Union for the Coordination of Transmission of Electricity (UCTE) is the association of transmission system operators in continental Europe for 23 countries. The UCTE network ensures electricity supply for some 500 million people in one of the biggest electrical synchronous interconnections in the world. The estimated plant capacity is 603 GW (end 2004) and the total primary control reserve is 3 GW.

This synchronous area is interconnected both internally and across borders.

The Synchronous Zone of Great Britain


The National Grid Company (NGC) is now the system operator of the electricity transmission system on the islands of Great Britain, including England, Wales and Scotland. In April 2005, the Scottish system came under NGC control, although ownership is still separate.

Distribution is handled by several separate companies and the capacity of power plants is about 81 GW. The system is interconnected by DC lines with France (2000 MW) and Northern Ireland (450 MW) and is able to sustain a loss of 1320MW.

The Synchronous Zone of (the Island of) Ireland


This smallest synchronous zone is operated by two TSOs: ESB and SONI. Their power system has a total installed capacity of power plants of about 7.6 GW and is connected to the Great Britain synchronous zone by a DC cable of 450 MW. The system reserve is 400 MW.

The Baltic Interconnected Power System


The interconnected grid of the Baltic States, Lithuania, Latvia and Estonia, is not synchronously linked to the power grids of other EU countries. There is a link with Finland, however, and links are also planned with Poland and Sweden. In 2006, the TSOs of these three countries established a cooperative organisation, BALTSO.

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