New standard for high-voltage substations

TenneT TSO operates the high voltage grid in the Netherlands. Electricity is transported across this grid at 110,000 Volts (110 kV) and higher. Transformers in the substations convert the electricity to a lower voltage level. Next, a Distribution System Operator– for example Enexis – ensures that the electricity is delivered to end users.

The customer’s challenge


Parts of the high voltage grid – like high voltage components – are approaching the end of their service life and have to be replaced. In addition, the grid must also be ready to accommodate the high demand for new connections for wind farms and solar parks, as well as data centres. This challenge can only be met by standardising and digitalising the substations. More than 145 substations will be replaced over a period of 10 years.

What are we doing for TenneT?

We are renovating three air-insulated substations at the Rijssen, Raalte and Terwinselen locations. These substations are the first to be replaced as part of the AIS Bay Replacement Program and form part of a Proof of Concept. The three substations will be renovated in phases. The first substation must be ready by mid-2021 and the last substation in the first half of 2022. A standard concept will be used for this purpose. The new fields are extendable and are constructed modularly.
The substations will also be automated. A digital fibre optic cable network will be installed in the high voltage substations to enable the various systems to communicate together. This replaces the old way of communicating between equipment using copper cables.

We have decided to work with skids for this Bay Replacement Program: prefabricated frames with the high voltage components mounted on top of them. These skids are built and tested in advance as a prototype at the Strukton site in Oldenzaal. A trial installation has been set up where various situations can be simulated, so that all equipment parameters can be tested. This trial can also be used to verify whether the new concept works in various situations as specified in the design. Following the testing period, the skids are transported to site and driven to the relevant bay  using a special ‘mover’. This is a safe and ergonomic approach. After this all that is left to do is to connect all of the plugs.

The Result

A standardised substation based on modular skids and a modern maintenance concept. In the event of a malfunction, the entire skid can be driven out and, in a safe zone, the technicians can repair it or even replace it with a new skid. In addition, the new concept allows components to be monitored more extensively, which makes it possible to better plan maintenance on the basis of this data. This prevents malfunctions and provides for an enhanced security of supply. If the modular concept proves to operate well in actual practice, it will also be implemented in the high voltage substations in the rest of the Netherlands.


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