Swissgrid AG

swissgrid - Measures to ensure a sustainable and secure supply of electricity

Grid stability thanks to solidarity

    Laufenburg (ots) - The situation in Europe is presently characterised by rising electricity consumption and a growing shortage of available grid capacity. In order to ensure a secure and reliable electricity supply in the future, Swiss operators of transmission and distribution grids aim to create the organisational and technical basis for automatic, frequency-dependent load shedding in all substations by the end of this year. These measures are being implemented in line with European regulations, which are also binding for Switzerland.

    In Switzerland, electricity is delivered via the medium of the national transmission grid at the high and extra-high voltage level (220/380 kV). This grid is, in turn, interconnected with the international grid of the UCTE (Union for the Coordination of Transmission of Electricity), which guarantees secure grid operation for 450 million people in 24 countries across Europe. Switzerland plays a pivotal role as a European electricity hub from which the entire national economy benefits.

    A UCTE directive, which is also binding for Switzerland, decrees that power stations must have reserve capacity at all times. In an emergency - for example, if an important power line or a large power station fails unexpectedly - these reserve power stations, which are already connected to the system, can be started up in a matter of seconds or minutes in order to restore the stability of the grid. If starting up the reserve power station is not sufficient, the transmission grid must be unloaded without delay. In case of an incident - in other words, if the frequency drops below the defined level - individual supply regions are disconnected by automatically shedding load. This relieves the burden on the system as a whole, since it reduces the number of electricity consumers. Switzerland's transmission system and distribution grid operators divide the country into a series of smaller areas based on non-discriminatory criteria. This enables load to be shed randomly in an emergency. Thanks to this approach, based on the principle of solidarity, the probability of being affected by a supply failure is identical for all consumers. Following the application of this "emergency brake", the original 50 Hz frequency is restored, and within a few hours all disconnected customers can once more be supplied with electricity.

    This measure protects the electricity grid as a whole and prevents power failures from impacting on large areas of Switzerland or possibly spreading beyond its borders. If this were to happen, it would probably take several days to restore stability to the grid, with grave consequences for Switzerland's economy. Serious damage to the power stations would also be likely.

    Since operators have a very limited amount of time to react, this frequency-dependent grid recovery procedure is carried out automatically. The necessary technical equipment - so-called frequency relays - will be installed by the Swiss electricity industry at all central points in the grid by the end of 2007. By introducing this measure, the Swiss electricity sector is making an important contribution towards maintaining a secure supply to Switzerland's economy in the event of unforeseen drops in grid frequency.

    This strategy of disconnecting sub-grids in order to facilitate reduced operation if the grid is jeopardised in the short term resembles the grid recovery procedures already initiated by the legislator to manage supply bottlenecks that are predictable in the medium or long term. The power supply utilities anticipate that the legal provisions necessary to implement the UCTE directives will be enacted by the Federal authorities on 1 January 2008.  

    For more information about load shedding, e-mail media@swissgrid.ch or call +41/58/580'24'00.

    moving power - swissgrid is the national transmission system operator. In its capacity as transmission grid operator, it ensures the secure, reliable and cost-effective operation of the Swiss high-voltage grid. Headquartered in Laufenburg, swissgrid employs approximately 130 highly qualified employees. As a member of the Union for the Coordination of Transmission of Electricity (UCTE) and the European Transmission System Operators (ETSO), it is also responsible for grid monitoring and grid usage with regard to European electricity exchange. swissgrid is wholly owned by the seven Swiss grid companies Atel, BKW, CKW, EGL, EOS, EWZ and NOK.

ots Originaltext: swissgrid
Internet: www.presseportal.ch

Contact:
swissgrid Media Service
Monika Walser
Werkstrasse 12
5080 Laufenburg
E-Mail:    media@swissgrid.ch
Internet: www.swissgrid.ch
Tel.:        +41/58/580'24'00
Fax:         +41/58/580'24'94



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