We spoke with our Offshore Wind Specialist and thought leader, Anna Hilden, for her insight into the latest changes and advances within the industry, specifically how the US can capitalize on existing experience in Europe.
Ensuring a secure and continuous supply of electricity.
For TenneT, one of Europe’s leading electricity transmission system operators, continuously monitoring the energy generated at offshore wind farms is key to maintaining the balance of the high-voltage grid, and to ensuring a future-proof renewable energy supply.
As a leading European transmission system operator (TSO), TenneT works to ensure an uninterrupted supply of electricity in their high-voltage grid for some 41 million people. The high-voltage grid is the backbone of the electricity supply system, connecting electricity producers to consumers. In the Netherlands, TenneT is the sole TSO of the national high-voltage grid, while in Germany, TenneT is the biggest TSO in the country. TenneT transports the biggest share of green energy in Germany, connecting and transporting electricity generated by offshore wind farms to the onshore high-voltage grid. The large-scale transition to renewable energy sources is well underway, yet it is a challenging task that relies on an advanced understanding of weather influences.
To ensure a secure and continuous supply of electricity, TenneT works 24/7 to maintain the crucial equilibrium of the high-voltage grid. The power grid is stable when the electricity that is generated corresponds with the electricity that is consumed. If the balance of the grid is disrupted, it may result in a power outage. To prevent this, TenneT continuously monitors the balance of the grid, and where the consumption of electricity is not equal to the feed-in, TenneT needs to use reserve energy to re-establish the balance.
In Germany, a significant portion of the country’s electricity is derived from renewable sources. In TenneT’s area of responsibility, the installed wind power capacity stands at about 24.4GW, where the solar power capacity is at about 15.5 GW.
TenneT provides electricity transport services, but most likely in stormy situations there is so much energy in the system locally that it can’t be transported efficiently. When this is the case, the grid can become congested. To resolve this, TenneT uses a tool box of measures, from basic grid operations up to interventions in the feed in of electricity. In order to manage this issue, TenneT also needed to be able to predict the feed-in of wind turbines and solar systems as precisely as possible, because renewable energy sources have a huge impact in the German grid. For this, advanced weather forecasting is vital.
In the case of offshore wind farms in the North Sea, TenneT needed to be able to both reliably estimate wind power production, and to forecast strong wind gusts to predict whether or not the wind farms will cut off an switch on again automatically due to security reasons. When there is too much wind, the wind farms cut off, leaving a deficit in energy that needs to be quickly found from an alternative source in order to stabilize the grid and restore balance to the energy system, ensuring that the European standard frequency of 50Hz is not disturbed and the security of supply is guaranteed.
“When there’s a storm coming and in five minutes you will have 4 or 5 gigawatts go down, then we have a serious issue,” said Freddy van Halm, Process and Metering Specialist at TenneT. “We are trying to deal with that, because we are responsible for the balance system in our region.”
TenneT needed an advanced weather risk assessment, ensuring a reliable cut off prediction of offshore wind farms in stormy situations.
Working with StormGeo has provided TenneT with the monitoring system they need in order to predict wind farm cut-offs, knowing in advance where and when the cut-offs could occur.
“The monitoring portal itself shows us a ‘traffic light’ visualization of wind confidence levels in three colors. It helps us to explain the behavior of our grid and our balance system. When we are aware that a wind front is coming, then we know in advance to be alert,” said Freddy van Halm.
StormGeo provides weather risk assessment through this ‘traffic light’ system, displaying wind confidence levels over time using a clear red, yellow, and green visualization approach. The portal provides advanced forecasting graphs that predict wind gusts, as well as wind speed and direction, taking into account the wind farms’ location and times of day. StormGeo also calculates the threshold for wind speed and cut-off points for the offshore wind farms, so TenneT can predict when a wind farm will shut down.
“When that’s the case, we know in advance and can calculate the influence it will have on our grid. It could mean that there will be a lack of energy into our system over a long duration, so we could ask the market to use other sources to fill in that gap,” said Mr. van Halm.
If the wind farms are going to shut down, and TenneT see the need to find electricity from an alternate source, they can plan this in advance, leading to the most efficient and cost-effective solution for everybody, and significantly reducing the annual costs to consumers.
The collaboration with StormGeo has been of great value to TenneT. “For us, it really works! We have a match. The cooperation with StormGeo is very good, it’s really a pleasure to deal with them,” said Mr. van Halm.
StormGeo’s weather risk assessment portal provides TenneT with advanced forecasts of wind gusts and storms, making wind farm cut-offs easier to predict and to plan for. In this way, TenneT can make informed decisions that ensure the equilibrium of their high-voltage grid. Alternative energy can be sourced in time and at a reasonable cost, and TenneT can continuously supply consumers with a stable flow of electricity.
“It gives us a view into the future – you have a very fast overview of what could happen to the wind farms. We know in advance when the transport will change in our grid, and we have to deal with that. Personally, I think that a system like this could be used by all wind farm owners and forecasters,” said Mr. van Halm.
StormGeo’s online portal also shows the estimated wind power production of the farms. “I think it’s a benefit to have such a system to look forward into the future,” said Mr. van Halm, “we see the estimated wind power production and that it will generate a specific amount of energy, and we can then predict the amount of energy they will deliver into our grid.”
Energy generated from offshore wind farms will become more important in the future. “The requests for renewable energy sources are growing rapidly across the world, and wind or wind turbines is a perfect method to fill in that gap,” Mr. van Halm notes.
“Europe will be going from fossil fuels to renewable sources. And for renewable sources, weather conditions are very, very important.”