Demo case: Optimal operation of water towers

In the demo project, Rune Grønborg Junker and the team at DTU Compute have used a water tower at Grundfos to investigate price-based management of flexibility.

Grundfos has implemented a controller based on the energy price in the water tower. The price of electricity helps to control how much water they will have to pump up in the tower, so that there is enough water for those who need it, but then you pump it up with the electric pumps as cheaply as possible. The water tower here symbolizes the ordinary consumer.

The Rune Grønborg team has based on real data from the water tower, found the connection between electricity prices and electricity consumption. They have successfully described this relationship using a model of stochastic differential equations. By predicting consumption based on this model, they have calculated how to turn up and down the electricity price to control the water tower’s electricity consumption so that it fell most appropriately.

The result showed that if the owner of the water tower could predict the future 100 %, then by buying into the Scandinavian spot market, the owner could save 5.4% on the electricity bill. By contrast, using DTU Compute’s model would save 4.1%, but at the same time, that simulation is true to reality.