Frequently Asked Questions - Operational management

To report disruptions in the EDINE electronic message system, please contact the TenneT Service Centre (see 'In general'). Our staff will put you through to a specialist in the Information Technology department.

You can report changes to the Service Centre. Our staff there will ensure that your change is forwarded to the appropriate department and processed correctly.

For further information please contact the TenneT Service Centre (see 'In general').

The transmission of electricity along the high voltage grid is dictated by demand and supply in the market. TenneT is furnished one day ahead with electricity transmission programmes (“T Prognoses”), in which generating companies and regional grid administrators outline, on an hourly basis, their planning for the requested transmission runs via the links with TenneT’s transmission grid.

Transmission constraints, i.e. situations in which the grid administrator is incapable of realising the market players’ requested transmission runs in compliance with the prevailing quality criteria, are to be avoided. TenneT in resolving a transmission constraint has a choice between charting alternative transmission paths along the grid and deploying reserve power. 

In addition to which it has the option of instructing the relevant electricity generator to downgrade (or upgrade) its production while instructing another electricity generator elsewhere in the country to upgrade (or downgrade). TenneT has the option of imposing restrictions on the market; forcing generating companies to stick to their previously submitted electricity transmission programmes (T Prognoses) in their production.

If the demand for electricity exceeds the supply, this may lead to a loss of ‘pressure’ on the grid. As a result, the 50 Hertz target cannot be achieved. This problem can be solved by temporarily increasing the amount of electricity generated by Dutch power plants (operated by electricity producers such as Nuon and Essent). This emergency capacity is reserve capacity contracted exclusively to TenneT, which means that it will always be available.

Further information: 'Operational management, operational reports'.

The quantities of power entering and leaving the country via the connections with Germany and Belgium are measured continuously. 

Further information: 'TenneT, publications, technical publications' (see the 'grid map' and the publication 'transmission on balance').

High voltage refers to electricity lines of over 100 kilovolts (kV). The following voltage levels are used in the Netherlands: 50 kV, 110 kV, 150 kV, 220 kV and 380 kV; abroad, even higher voltage levels are permitted.

The regional electricity producers supply power to TenneT. In addition, TenneT acquires power from other countries, which it then transmits across the Dutch high-voltage grid.

The total demand for electricity at the time of the peak load (see also ‘peak usage’) amounts to approximately 15,000 megawatt. On average the demand is around 12,000 megawatt. Note: In reality, this value is even higher, but the actual figure cannot be determined (as TenneT does not administer the entire high-voltage grid at present). 

Further information: 'TenneT, publications, technical publications' (see the publication 'transmission on balance').

In winter at dusk, peak loads will occur because people switch on the lights in their homes earlier, turn up the heating and start using other equipment. During hot days in summer, people increasingly make use of air‑conditioning systems. These use a lot of power. As an indication, in 2005 the peak load (i.e. the highest load) was observed on 9 December between 5.30 and 5.45 p.m. In 2004 the peak load occurred on 21 December between 5.15 and 5.30 p.m.

Further information: 'TenneT, publications, technical publications' (see the publication 'transmission on balance').

If the demand for electricity exceeds the supply (i.e. the production) this may cause a shortage. Another reason may be that part of the production capacity is unavailable, for instance due to failure at a power plant.

Energy cannot be stored. Accumulator systems can be used for small amounts but this is not possible with high voltages. In case of overcapacity, energy is sometimes ‘dumped’ to ensure that the supply/demand balance can be maintained and the frequency remains at 50 Hertz. This way, the grid and the transmission equipment will not be overloaded.

Yes. By switching off certain parts of the grid, TenneT can free up lines in order to remedy disruptions. If a fault has occurred at one of our own stations, TenneT can also work on solving the problem. If the fault occurs in parts of the grid administered by other parties, TenneT can only play an indirect role.

Generally, the Dutch electricity grid can be considered highly reliable. The infrastructure is solid and we perform systematic maintenance activities at regular intervals. As a result, the materials are quite sturdy. The risk of failures only increases in extreme cases, when several adverse weather conditions occur at the same time.

In extreme cases, when several adverse weather conditions occur at the same time (such as snowfall or ice formation in combination with fierce wind), the round steel cables become frosted and they can get an wing-like shape and consequently they will catch a lot more wind. In the event of high wind speeds, the cables can be blown against one another or even break.

Failures can occur as a result of extreme weather conditions or human errors during maintenance work. In addition, a sudden influx of power from abroad (for instance when wind farms in Germany become operational) may upset the balance. If TenneT does not respond in time, this may cause failure of or damage to electrical equipment.