How hydropower can strengthen and streamline the electricity supply
Hydropower is unmatched in storing energy for long periods and balancing the electricity system. Viktor Döhlen has researched how smaller energy storages, like batteries, can integrate with hydropower to balance the grid over shorter intervals and contribute to a more stable electricity network.
Hydropower is a safe and stable source of energy in the Swedish energy mix. But what is needed for it to be able to regulate and stabilize the energy system? For three years, Viktor Döhlen, as an industrial doctoral student at Sollefteåforsen, has evaluated the combination of hydropower and energy storage.
“Historically, hydropower has provided the support services to the electricity grid called frequency regulation services. With new demands on these services, some hydropower plants have difficulty delivering and therefore need to be combined with energy storage. The final product will be a small investment for a hydropower plant, but offers great potential to regulate over short and long time intervals,” says Viktor Döhlen.
Regulating and ensuring stability
The speed of change and regulation is a key issue. Without it, hydropower does not live up to the requirements that Svenska Kraftnät places on suppliers to the power grids. It is both about being able to regulate in the event of a decline or increase in electricity production and ensuring the stability of the electricity grid even in the event of abrupt interruptions.
“By measuring how far the power plants are from meeting the requirements, we can evaluate how large energy storage is required to meet them. says Viktor Döhlen.
In some cases, the hydropower plant can make minor upgrades to meet the requirements. But in cases where it is far too expensive an investment, it may be better for the power plant to invest in storage capacity. Since the power plant has a lot of energy in the stored water, Viktor has focused on power density when evaluating an energy storage to combine with the hydropower plant.
Can reduce wear and tear
“At Mid Sweden University, we are developing an energy storage system based on supercapacitors. To reduce costs, the research group in power electronics is working on a prototype of an inverter that streamlines and reduces the cost of the peripheral equipment,” says Viktor Döhlen.
Another benefit of the combination of hydropower and energy storage is that wear and tear can be reduced on moving parts in hydropower plants, which are otherwise adjusted to constantly balance the electricity grid.
A lot has happened in battery research. Hydropower plants compete in the market for ancillary services with a large number of batteries that have been connected to the electricity grid in recent years. With the digitalisation of electricity networks, electricity users are connected to the grid and can be involved in regulating the frequency.
“This is very good news for the electricity grids, but sometimes there are difficult competitive conditions for hydropower. So the energy storage systems must be efficiently dimensioned for hydropower to continue to compete,” says Viktor Döhlen.
Security of electricity supply even in a crisis
On 19 December, Viktor will defend his licentiate thesis. But the aim is already set on further research.
“Now we want to continue working to ensure stability requirements, especially in conditions where the electricity grids are very strained, such as during major outages. These are important capabilities to ensure a secure electricity supply even during crises. There should be a solid place for energy storage, and especially in combination with hydropower. Research has a major role to play here,” says Viktor Döhlen.
On 19 December, Viktor Döhlen will hold his licentiate seminar where he defends his thesis: “Enhancing hydropower with energy storage systems – Merging perspectives on inverter design and industrial application”.