Keeping the transmission system stable, safe and secure takes seamlessly operating infrastructure, continuous management of power flows and cooperation with partners. In addition to transmitting electrical energy, Swissgrid provides ancillary services to ensure the secure supply of electricity.
Swissgrid does not generate any electricity, but transports the energy produced by the power plants to the consumption centres. The power plant operators help Swissgrid ensure grid stability by providing control energy. This is a reserve that Swissgrid uses in the event of an imbalance between production and consumption: when electricity consumption increases, Swissgrid has them feed more energy into the grid. When it falls, less energy is fed in.
The transmission system only works when the production and consumption of electricity are in balance. That makes Swissgrid's grid control rooms the heart of the transmission system. From here, operators monitor the grid around the clock and ensure that this balance is always maintained and the energy is transported safely and securely. They coordinate the electricity generation timetables, preventing congestion and overloading. This is achieved, for example, by connecting and isolating lines in switchgear systems or by a redispatch, i.e. instructing different power plants to increase or reduce their output.
Swissgrid doesn't just invest in the operation and modernisation of the transmission grid to ensure system security; it also invests in market development. By structuring tenders for the national and domestic procurement of control reserves more efficiently, Swissgrid can access more providers and so reduce procurement costs. Swissgrid also develops innovative product solutions and new price mechanisms which helps providers such as hydropower plants to better market their high level of flexibility in production, and to enable the use of new technologies, such as batteries.
Swissgrid inspects, maintains and repairs pylons, lines, substations and switchgear systems as and when required. This is the only way to ensure that the equipment can be operated safely. The responsibility for doing so lies with the plant managers who work at the seven locations.
Swissgrid is responsible for the planning, replacement and dismantling of the entire transmission grid infrastructure. This is a challenging task, because bottlenecks already exist, new power plants are connecting to the grid and momentum on the electricity markets is constantly increasing. Further development of the transmission grid therefore required. All this does not automatically mean more lines, but primarily systematic modernisation and even dismantling.
Switzerland is part of the European interconnected grid – a form of networking and international cooperation which it relies upon. To overcome electricity bottlenecks in the winter months, for example. And to compensate for power plant failures or over-production. In return, as a transit country and with its pumped storage power plants, Switzerland plays an important role in this integrated European system as a major energy storage facility.
With the exception of the Swiss Federal Railway (SBB), no consumers are connected directly to the transmission grid. In spite of that, the consumers play an important role in ensuring the stability of the grid. If there is a threat of an imbalance, Swissgrid asks refrigerated warehouses or waste incineration plants, for example, to cut down their energy consumption.
The switchgear systems housed in the substations are nodes between lines. Here, the energy is transformed to a lower voltage level and passed on to the lower grid levels. Swissgrid’s grid control rooms also isolate and connect lines in the switching substations by means of switching operations, in order to guide the energy flows.
Before the energy produced by the power plants can be used by the end consumers, the voltage is reduced through seven grid levels to 400 and 230 volts. In addition to extra-high voltage, high voltage, medium voltage and low voltage, these levels include three connecting transformer levels.
The Swiss transmission grid extends across 6,700 kilometres of lines, 12,000 pylons and 125 substations with 146 switching substations, as well as 41 connections abroad. It is comprised of both 380 kilovolt and 220 kilovolt lines: While the former are used mainly to import and export electricity, the large Swiss power plants feed the majority of their energy into the 220 kilovolt grid. This high-tension voltage is necessary in the transmission grid in order to transport energy over long distances with as little power loss as possible.
The extra-high-voltage grid forms the backbone of a secure electricity supply. Swissgrid works around the clock to ensure that it runs stably, safely and securely at all times. We operate cost efficiently and with consideration for people and the environment. We are already planning and building the grid of the future and making an important contribution to the energy transition.
