Optimisation of joint operation of fast and slow storage reservoirs

Kaplan units face issues with meeting the updated requirements for Frequency Containment Reserve (FCR) on the grid as they are formulated on behalf of the harmonising in ENTSO-E. In this project the aim is to develop regulation strategies for the combined fast energy storage unit and the hydropower unit. There is a need for knowledge in how to design and operate such combined hybrid power plants and how to work with potential challenges that might arise.

Hydropower is the main provider of system services (such as FCR, FRR). To keep its position and ensure future delivery, hybridization through fast energy storage unit with the hydropower unit is an option. Due to their high yearly running hours and thus lower operational costs, Kaplan units present a valuable resource for FCR. Combining the relatively slow hydropower system with a fast-acting storage system based on other techniques can provide benefits for both technologies, some of which are listed below:

• Wear and tear on the slow reserve (hydropower plant) can be reduced,
• faster joint response is possible,
• the size of the storage unit can be made smaller, compared to standalone operation, since it does not have to cover longer time scales,
• most optimal product provides the reserve,
• other operating modes can benefit from the storage system and
• hydropower can be competitive in a changing market situation.

In this project regulation strategies will be developed to enable the hydropower industry to achieve such benefits.