Making our power grid innovative and robust
An always-on power supply is something we take for granted. Yet, it’s not something that just happens all by itself. Strukton and TenneT work very hard to make our power supply future-proof. Vincent de Vries (Lead Engineer and Technical Manager at Strukton Systems) and Roland van Dalen (Lead Engineer at TenneT) wrote this blog on the subject.
Before we tell you what a future-proof power supply entails, we first need to give you a ‘brief intro to transformer stations’. The Netherlands has hundreds of 110/150 kV transformer stations that supply power to the surrounding regions. There are two types of such installations: air-insulated stations (AIS) and gas-insulated stations (GIS). Air insulated means that air prevents us from coming into contact with the voltage, for example because the cables are suspended high up in the air from pylons. In case of GIS, the voltage is insulated using a special type of gas. Thanks to this gas, the conductors can be placed closer together and these stations are therefore considerably smaller. A drawback of the gas is that it is toxic. Furthermore, it is a greenhouse gas and therefore bad for the environment.
"If we were to do nothing, this could endanger the electricity supply system"
Due for retirement
About one hundred and fifty transformer stations – not to mince words – are old and due for replacement. This is not only due to their age, but also because of today’s requirements. Energy generated by solar parks and windmills, high power consumption by data centres, increasingly more private homes with solar panels on their roofs that supply electricity back to the power grid and electrical cars; all this requires robust transformer stations. If we were to do nothing, this could endanger the electricity supply system.
So there is plenty to do! TenneT aims to replace the old stations over a period of ten years. This is being done on the basis of a well-thought-out approach, starting with a proof of concept. TenneT has asked the market to come up with a new concept, for AIS as well as GIS. These concepts will be tested on a number of stations. The concept that works best will be used for the transformer stations in the rest of the Netherlands. We do not want to endanger the power supply by pioneering in this area. Strukton emerged as one of the winners for AIS as well as GIS during the tender for the first phase. Last summer we signed the contract for the implementation and construction. By the end of next year, the ‘turnaround’ must be entirely complete.
"It is possible to remove the roof from the building, so that the GIS can be lifted into it in its entirety"
Wood does not burn
Strukton has conceived of an innovative concept for the gas-insulated station. All installation components will be delivered ready-made as much as possible. This starts off with the building housing the GIS. This building will have a prefab concrete foundation and its structure is no longer made of steel, but of wood. A fire hazard, you think? On the contrary. Only the outside edge will burn, but not the core. In other words, as long as the beams are thick enough, a wood structure is safer than steel. And, furthermore, more sustainable. In addition, it is possible to remove the roof from the building, so that the GIS can be lifted into it in its entirety. This is because the GIS is positioned on a skid, a kind of frame. This is highly innovative. Once it is lifted into the building, it is directly in its proper place. Spending weeks on construction, filling and on-site testing is therefore a thing of the past. Next, it is a question of inserting the proverbial electric plugs and we are done.
One of TenneT’s requirements is that the concept must be safe in terms of design, construction and use. This is why it always is a topic on each agenda. As mentioned earlier, the gas in a GIS is toxic. To prevent any danger to technicians, we are installing detection sensors and an alarm. The building will be well ventilated, although this may not be the best solution. In such an environment, the gas would simply disappear into the outside atmosphere, which does not sit well with Strukton’s and TenneT’s sustainability policy. Capturing the gas is an option and we are investigating this option. This way we are constantly weighing the pros and cons of the risks, residual risks and backup scenarios.
We have been doing this at Strukton for years and have suitable systems in place for this purpose. This results in a consistent, integrated and traceable approach. TenneT is very pleased with the degree of dependability this provides.
Dynamic energy flows
The technology innovation also requires a very different way of working. We are moving from engineering to configuring and from in-situ to prefab. For TenneT, too, this represents a significant innovation. We are not only doing different things, but we are also doing things differently. The GIS and AIS project groups champion the innovation and together with Strukton are reviewing the TenneT organisation to tweak it wherever necessary. Slowly but surely more and more TenneT colleagues are getting on the bandwagon on the way towards the stations of the future, so that we are optimally prepared for the dynamic energy flows needed by society in the future.