Planning for winter

Ensuring secure grid operations in Switzerland is always more challenging during the winter. In Switzerland, more energy is consumed in the winter than in the summer. Switzerland is therefore dependent on imports in winter to cover the increased domestic electricity demand.

The grid situation in Switzerland is currently stable and non-critical. Once again Swissgrid has achieved several improvements for the winter of 2017/2018, compared with the previous year, and they will guarantee Switzerland’s grid capacity.

  • Transformer capacity: A new 380/220kV transformer was put into operation at the Beznau substation in March 2017. The renovation of the 380/220kV transformer in Mettlen and the Laufenburg substation has been completed.
  • Control energy reserves: With an eye to the winter planning, Swissgrid procured part of its control energy in advance in the autumn of 2017. This early procurement increases the ability of the the power plant operators to plan ahead, and it also provides Swissgrid with some long-term security.
  • Net import capacity: Switzerland’s net import capacity was already increased in the winter of 2016/2017 and is once again available to a similar extent for this winter. However, in order to completely use these capacities, the foreign transmission grid operators will have to be able to provide corresponding export capacities.

The current grid situation is being continuously analysed with the foreign transmission grid operators.

Swissgrid is responsible for operating, maintaining, modernising and expanding the transmission grid with voltages of 380 kV and 220 kV on grid level 1 to meet demand. Swissgrid thus plays an important role in maintaining security of supply in Switzerland.

Because of its greater transfer capacity, the 380 kV grid is used to transport and exchange electricity with other countries. A large part of domestic production occurs at the 220 kV level. Switzerland’s energy is also supplied primarily via the 220 kV grid and other transformation systems at lower grid levels.

During the winter half-year, 75-85% of imports and 80-90% of exports are transported at the 380 kV voltage level. In the case of imports, this usually happens via the cross-border lines with the northern neighbours France, Germany and Austria.

The capacity of the transformers that convert the energy from 380 kV to 220 kV largely determines how much imported energy can be used to supply Swiss consumers. As the capacity for transforming from 380 kV to 220 kV is limited, imports can only be utilised to a limited extent to cover Switzerland’s electricity demand.

Structure of the Swiss transmission and distribution grid

During the winter, Switzerland’s energy supply is met by domestic production and net imports from neighbouring countries. In addition to the available base-load energy, the utilities also use water reserves from the reservoirs to cover part of the consumption with peak energy. The amount of peak energy supplied by storage power plants depends on the electricity demand.

  1. Switzerland's electricity consumption and how this demand can be met can be explained using the example of a bathtub. The bath represents consumption. The greater the consumption, the larger the bath.
  2. The electricity supply can be represented by the quantity of water in the bath. It is made up of various components:
    1. Net imports: these imports are largely delivered via transformers from 380 kV to 220 kV and lower voltage levels to the consumers.
    2. Energy from nuclear and run-of-river power plants: Both types of power plants supply so-called 'base-load energy' and account for a significant proportion of the water in the bath.
    3. Energy from storage power plants: the water in the reservoirs forms an energy reserve, which empties between around October and early May each year and is replenished in the summer months. Storage power plants supply so-called 'peak-load energy'.
  3. The bath also has a tap and a plug hole. The inflow from the tap represents imports and the outflow through the plug hole represents exports of energy abroad. The difference between inflow and outflow represents the net imports. Any energy which is exported is not available to supply to consumers in Switzerland.

Energy supply and consumption in Switzerland

The reservoir levels are published weekly by the Swiss Federal Office of Energy (SFOE) and provide information on the water reserves available for electricity generation in Switzerland. The Swiss storage power plants are the only flexible domestic power resource and therefore play a central role in guaranteeing secure grid operation. They provide control energy in order to ensure a constant balance between electricity consumption and production, and they can be deployed in critical grid situations for redispatch measures. The responsibility for reservoir management lies with the power plant operators.

Date Description Format
12.03.2018 Current reservoir levels PDF

During the winter of 2015/2016, energy companies, grid operators and authorities successfully cooperated to cope with the strained energy and grid situation. The situation was analysed in the «Winter working group», and various measures and solutions were developed that are having a lasting and positive effect.

Swissgrid and ElCom recommend agreeing on a plan early so all the players can act quickly and decisively should the situation intensify in the winter.

There are currently no plans to convene the «Winter working group».

Netto Import Tool

As proposed by the working group on «Responsibility for the security of electricity supply», the «Netto Import Tool» should provide market participants with information about the maximum net import capacity of Switzerland. The net import capacity is the amount of imported energy that can be transformed unto the lower voltage levels in order to serve customers in Switzerland.

The tool allows market participants to estimate the Swiss net import capacity for different load-flow scenarios. This should help them to plan their portfolios in a such a way that they can fulfill their contractual and in some cases legal obligation to deliver energy and be balanced. Please note that the results are indicative only. The assumptions and limitations for the calculations are specified in the worksheet.

Date Description Format
30.01.2017 Netto Import Tool XLSB