High and very high voltage substations: role and structure

The role of the transmission network is to transport energy from production centers to consumption points or delivery points. It is made up of overhead or underground lines forming a meshed network linking different points in the country, enabling the pooling of production resources that supply end customers. This network is made up of electrical nodes called "substations", which have a triple function:

• the interconnection of lines of the same voltage;

• evacuation of energy from generation sources to the grid;

• the connection between networks with different voltages.

The architecture of substations is governed by a number of specific rules, depending on their size, the number of facilities they connect, the voltage level and the level of safety required. This document sets out the different substation architectures available to RTE, specifying their roles, advantages and possible disadvantages.