A closer look at the Smart District Heating Controller
One of the Enabling Technologies that is being developed by the Push-It project is the Smart District Heating Controller. This controller should monitor and control the heating system. That is all well and good, but how does it work? What are the challenges the team is facing? What is the current status of development? We asked Bram van der Heijde, who is a developer on this part of the project.
What exactly is a Smart District Heating Controller?
Just like a car needs a driver, any complex energy system needs to be controlled. The Smart District Heating Controller is the brain of the district heating system and decides which sources produce heat (or cold) at any time, and when the heat storage systems need to be charged or discharged. The controller uses a kind of crystal ball to predict the future: weather conditions and heat demand in the network. Based on the prediction, it calculates how the system should be operated, for instance to minimize the operational costs, maximize the output of the geothermal energy systems and/or minimize heat losses.
What is needed to develop this controller?
Most importantly, the controller needs an accurate model of the system. Without a model, it would not be possible to calculate how the system should behave to reach the control objectives. Also, if the model does not represent the system well, the proposed control actions will not be optimal when applied to the real system.
The development of good models requires data to make sure that the model accurately reflects the real system.
In addition, also when the controller is in use, sensors need to communicate the actual state of the real system to the controller. Imagine that the controller assumes a well-filled heat storage, when in reality it’s almost empty: of course the proposed control action will not be helpful in that case.
Finally, the controller needs to be able to pass instructions to the actual system components. This requires changes to the control equipment.
How is the controller tested?
The controller will be tested in three locations within PUSH-IT: Delft, Darmstadt, and Bochum. These three demo sites are all different and hence need tailor-made controller models and algorithms. In a first step, virtual demonstrators will be built, that mimic the behaviour of the real demonstrators. Once the controller is proven to perform well in the virtual demonstrators, and the real demonstrators are finished, the controllers may also be tested in real-life.
What are the challenges in developing it?
The time scale of the heat storage systems in PUSH-IT is a big challenge. Most of the storage systems are intended for seasonal storage, such that excess heat from summertime can be used during wintertime. The controller’s crystal ball needs to be able to look ahead at least one year, which is (much) longer than is usual for smart district heating controllers. Usually, the controller only looks ahead for a few days. But that would mean the controller is not aware of changes in demand in the following seasons, which would mean the storage systems would be insufficiently charged, or discharged too soon. A longer prediction horizon will solve this, but also means the controller needs more (and likely too much) time to calculate the optimal control actions.
We are investigating how we can tackle this challenge, for instance by splitting the control problem into a long- and short-term optimization.
Another challenge is the time needed to build these systems. Delays in construction of large-scale infrastructure are to be expected; that means that we may not be able to fully test the controller in reality. The virtual demonstrators address this challenge, and provide a sandbox for controller development, even when the real demonstrators are still under construction.
How far along is the development at this point?
As the real demonstrators are slowly taking shape, we are now defining the scope of the controllers for each of the three demo sites. Before we can develop the actual controller models, it is important to define exactly what will be controlled (pumps, buildings, supply temperatures in the heating network, etc.) and what should be the control objective (minimum cost, minimum peaks in the demand, etc.).
Meanwhile, the virtual demonstrators are under development. As soon as they are finished, we can start developing and rolling out controllers for the virtual demos and gain valuable experience for the application of the smart controller in reality.
PUSH-IT is a project funded by the European Union’s Horizon Europe research and innovation programme under grant agreement No 101096566.
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them.
