Increased grid capacity by using batteries to create virtual power lines
There is a need to increase grid capacity, but it can take many years before new power lines are in place. “Virtual power lines” is a concept where batteries are used to control the electricity flows, enabling a higher utilization of the existing grid. Martin Lundberg, PhD student at Lund University, has in his research shown that it is technically possible and safe to use batteries, and other resources, to increase the grid capacity without exceeding its physical limitations.
What is your background, Martin?
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“I started my studies at Uppsala University and then continued as a PhD student in Lund with Professor Olof Samuelsson as my supervisor. For my first two and half years, I was in a European project working on accelerating the integration of renewable energy in distribution networks. Then SESBC started, and I continued in the project Managing grid capacity with storage. I will defend my thesis in October this year.“ |
What is this project about?
“The goal is to find ways to use energy storage solutions to quickly and safely increase the capacity of the power grid. There are physical limitations in the power grid for how much electricity can be transferred, and more capacity is needed to handle the large expansion of renewable energy production. Wind turbines and solar panels can be constructed relatively quickly, but adding more power lines to increase the capacity can take many years. What I have done is to analyse how batteries and other resources can be controlled to make sure the full capacity of the grid is used but not exceeded. I have also investigated what can be described as virtual power lines. These virtual power lines, that consist of batteries, can increase the capacity of the existing grid without the need of building new lines. The idea is that these types of solutions can be implemented much faster than new power lines so that it will be possible to connect more renewables to the grid faster.”
What do you mean with virtual power lines?
“The concept of a virtual power line is when you are using batteries to store surplus energy and transfer it later when there is grid capacity. For example, take a power line connected to a large wind farm has a 100 MW limitation, but you have a temporary high production, and for, say, an hour, you want to continuously transfer 200 MW. With a virtual power line, you would transfer 100 MW through the power line and charge the remaining 100 MW into a battery at the beginning of the line. At the same time, 100 MW is discharged from another battery at the end of the line. The result is that 200 MW is transferred, with 100 MW through the actual power line, and 100 MW is transferred ‘virtually’ by the batteries. During periods of low production, the stored excess energy in one battery is used to recharge the depleted battery on the other side, which ‘resets’ the virtual power line.”
What about safety?
“In the grid, there are capacity margins for handling component failures. For example, if one power line fails, it is compensated for by transferring more power through the remaining lines. To do that, lines normally have to be operated well below their maximum capacity. I have done calculations that show that the concept of virtual power lines can replace some of the safety margins within the system. If the batteries handle component failures, then it’s possible to use a larger share of the power lines’ maximum capacity.”
Can you describe your research making this possible?
“To keep it short I have developed control algorithms for batteries and other grid resources to handle grid capacity. I have used analytical methods and simulations to test that it’s technically possible, and of course that it doesn’t create negative impacts on the rest of the grid. If anyone wants to dig deeper, I recommend reading more about virtual power lines here and the coming thesis summarising the research. You are also most welcome to contact me.
What happens next?
“My work indicates that it’s possible to use batteries to increase the grid capacity. The next natural step would be to test these findings with actual batteries in experiments. There is an upcoming post-doc project in the centre addressing this.
Contact
Partners in the project "Managing grid capacity with storage"
Lund University, Chalmers, DNV, Göteborg Energi, Hitachi Energy, Svenska kraftnät, Vattenfall Eldistribution, Volvo Energy, Swedish Energy Agency