What is a substation?

A substation is an electricity facility that is vital for the operation of any electricity system and whose function is to interconnect various elements within the grid.

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A substation is an electricity facility that is vital for the operation of any electricity system and whose function is to interconnect various elements within the grid in order to transport the energy generated in power stations to consumers. This function usually requires the electricity voltage to be changed so as to suit each case: increasing it when large amounts of electrical energy need to be moved over long distances or decreasing it when delivering it to end consumers.

We generally refer to three types of substations, depending on their function:

- Generation substations, which raise the voltage of the electrical energy coming from a generation station in order to evacuate it to the grid.

- Transmission substations, which interconnect several high-voltage electricity lines to achieve a meshed power grid, either directly, if they are of the same voltage, or by means of transformers, if they are of different voltages.

- Distribution substations, which interconnect several electricity distribution lines and supply other lower voltage distribution networks that carry electricity to end consumers.

Additionally, at the substation, all the information regarding the operation of the equipment and elements of the transmission grid (disconnecting circuit-breakers, switchgear, transformers, etc.) is collected and is continuously sent to the Electricity Control Centre (CECOEL) of de Red Eléctrica de España.

In the CECOEL, along with the data received from all substations of the grid, the operation of the electricity system as a whole is analysed and appropriate decisions are taken to ensure the security and continuity of the electricity supply: connect, disconnect, increase or decrease electrical energy, etc.

What is a substation?