The voltage increase of the Bassecourt – Mühleberg extra-high-voltage line will be delayed due to objections submitted to the Federal Administrative Court. The installation work for a new Swissgrid transformer in the Mühleberg substation continues.
On 22 August 2019, the Swiss Federal Office of Energy approved the voltage increase for the extra-high-voltage line between Bassecourt and Mühleberg from 220 to 380 kilovolts and dismissed the objections. These are generally related to the load from magnetic fields and the noise or demanded that the line route should be relocated or cabled. Various appellants have appealed to the Federal Administrative Court against the decision made by the Swiss Federal Office of Energy. This is expected to delay the voltage increase of the Bassecourt – Mühleberg line by two years.
The modernisation of the line requires adjustments to some of the existing pylons and will not change the landscape. Construction work is planned on 54 of a total of 142 pylons: individual pylon foundations will be reinforced, double anchor chains will be installed, or the cable winch tension will be increased.
Supply of electricity in Greater Bern secured
The reinforcement of the Bassecourt – Mühleberg line is part of Swissgrid’s «Strategic Grid 2025» and, together with further projects, is important for the security of supply in Switzerland. The «Strategic Grid 2025» is focused on the federal government’s energy perspectives and takes the decommissioning of the Mühleberg nuclear power plant into account.
The decommissioning of the Mühleberg nuclear power plant will result in the removal of part of Switzerland’s energy production in Central Switzerland from the end of 2019. In the medium term, this missing feed-in will have to be offset by increased production by Swiss power plants or energy imports from abroad. To enable the additional imports, the existing capacities of the extra-high-voltage lines and transformers between Bassecourt and Mühleberg need to be expanded. This is particularly important in the winter months, when Switzerland relies on additional energy imports.
In a normal supply situation, Greater Bern will receive an adequate supply of electricity, even after the Mühleberg nuclear power plant is decommissioned. In the event of short-term grid congestion, the Swissgrid grid control room can take various measures, such as switching operations or interventions in electricity generation (redispatch) or measures on the power market (NTC adjustments), to respond to the situation and ensure grid stability. Swissgrid needs the 380-kV connection between Bassecourt and Mühleberg to ensure the security of supply in the medium term.
New transformer in the Mühleberg substation
Swissgrid is installing a new transformer in the Mühleberg substation. Together with the voltage increase in the extra-high-voltage line, the transformer in Mühleberg will ensure that the imported electricity can be converted to the 220-kV voltage level (supply level). Swissgrid had previously already replaced the outdoor switching station in Mühleberg with a gas-insulated switching substation.
The additional transformer capacities are an important element of Swissgrid’s «Strategic Grid 2025», which plans for additional transformers in Mühleberg, Laufenburg, Beznau, Chippis, Châtelard and Romanel. Around 90 percent of the exchange of energy with foreign countries is carried out via the 380-kV grid. The transformer capacity has been limited to date and is preventing the full utilisation of the electricity imports.