Interview with David Landier, Head of Substation Department at RTE
RTE (Réseau de Transport d’Electricité) is a French system operator with about 8,500 employees and a revenue of around 4 billion euro. Since we are still investing a lot in our grid, our annual investments come at 1.5 billion euro. One of the factors driving these large investments is the development of renewables, which is on a sharp rise in France, so we need to develop new lines, interconnections and substations in order to integrate the renewable sources of energy into our grid.
RTE operates the transmission and sub-transmission grid in the mainland, continental France, so we are not responsible for the distribution network and we do not operate on the islands. We operate 105,000 kilometres of lines, of which about 5,000 kilometres are underground. In terms of the voltage level of our assets, we deal with the ratings above 45 kV.
RTE operates about 2,700 substations and 1,300 transformers – most of which are 400 kV and 245 kV, with a total installed power of 225,600 MVA. An average age of our units is around 38 years, with the oldest unit being around 70 years old.
Our transformer design process was put in place years ago and it is very standardized. This means that all our transformers are standardized, and we have a very limited number of them. In fact, we cover all of France with practically only six different transformers for the main network, and these include:
- autotransformers of 600 MVA, 400 kV / 225 kV;
- full size transformers of 240 MVA, 400 kV / 63 kV or 400 kV / 90 kV; and
- full size transformers of 170 MVA, 225 kV over either 63 kV delta or 63 kV star connected or 90 kV star connected.
These are the types of transformers that we buy now, and we have a few other types left over from the legacy.
Annually, we invest around 30 million euro in new transformers, which is around 20 units, excluding the phase shifters. There are about 10 phase shifters in our grid.
Qualification of factories
RTE has in place an investment policy for procuring new transformers, which allows us to buy only from qualified factories. The assessment of factory’s capability is extensive and involves looking at not only manufacturing capability, but also the design and testing capabilities.
The qualification procedure is also specific in the way that we qualify factories by the product and voltage class. Some factories are able to supply for 220 kV, some can supply for 400 kV, and so on. The qualification for one product or the voltage class does not impose the qualification of the full product range.
So, our tenders are open only to those manufacturers that pass assessment, while non-qualified suppliers are not allowed to submit their offers.