Transmission services

TenneT transmits electricity throughout the Netherlands. To provide this service, TenneT operates a large and essential transmission grid: the Dutch national high‑voltage grid. TenneT makes the grid available to market parties (including electricity producers and regional grid administrators). TenneT is impartial: any party that meets a set of strict conditions can make use of the high‑voltage grid.

From whom to whom?

TenneT transmits electricity from electricity‑generating companies (the producers) to regional grid administrators (the customers). TenneT does not produce any electricity itself and does not 'own' the power – it merely makes the transmission grid available. Furthermore, TenneT does not transmit power to consumers and businesses. That is the task of regional grid administrators. Power is transmitted to consumers and businesses via the lower distribution grids.

Transmission and distribution grids

Special requirements are imposed on the backbone of the electricity infrastructure. The basic principle is that we cannot allow the lights to go out, whatever happens. Although in terms of voltage levels there is no clear distinction between transmission and distribution grids, the transmission grid clearly fulfils a different role than the distribution grid. The actual purpose of the transmission grid (≥ 110 kV) is to realise connections between the various power plants and between the power plants and the distribution grids (≤ 50 kV). As a result the power plants and the transmission grid form a single, combined system intended to assure the required security of supply. Disruptions may occur at power plants, but the transmission grid, which has been provided with a certain amount of redundancy, ensures that the supply system as a whole practically never fails: the transmission grid acts as the backbone for the reliability of the entire system. In reality, the social standard applied is that the transmission grid may never fail due to the social and economic impact of a grid disruption. This is why the system has been set up in such a way that parts of the grid may fail without this leading to transmission disruptions. This is referred to as the N-1 criterion. The hours per year when Dutch citizens do not have access to power are almost entirely caused at the distribution level – as a result of a district, municipality or region being cut off from the system because a cable has been damaged during digging activities, for example.

How does TenneT transmit power?

Power is transmitted both above and below ground. Above ground, it is transmitted through 380 kV and 220 kV electricity lines that are suspended from high‑voltage pylons. Power is also transmitted through 150 kV high‑voltage cables that are installed below ground–just like water mains.

How much power is transmitted?

On any given day, TenneT knows how much electricity it will have to transmit the next day. This is indicated in daily transmission forecasts known as 'T prognoses'. These estimates are submitted by electricity producers and regional grid administrators and include hourly forecasts of the required electricity transmissions for the next day. On the basis of these forecasts, we can calculate whether the high‑voltage grid will not become overloaded. This is done by means of so‑called load‑flow calculations. If the grid is likely to become overloaded, TenneT can divert the electricity via an alternative route. On average TenneT transmits 3500 megawatt‑hours of electricity per day.

Security of supply

An electrical current always chooses the path of least resistance. TenneT can control the direction of the current by ensuring that more power is produced or consumed in certain parts of the grid. If there is a 'bottleneck' somewhere in the grid, TenneT will 'push' or 'pull' harder to send the electricity in another direction, as it were. TenneT can also transmit power in two directions because large sections of the high‑voltage grid are redundant. If a line fails, TenneT can make use of the 'back‑up line'.

Maintenance and management

TenneT manages and maintains the national high‑voltage grid. We do this by conducting regular inspections and performing maintenance and repair work.