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Sidensjo wind farm supports the electricity power system by down-regulating its production

Sidensjo wind farm in Sweden has been approved on its application to supply with FCR-D down and has participated in the market several times since then to support the power system. If necessary, the wind farm has the option of reducing its production within a few seconds to stabilize the frequency in the event of a disturbance in the power system. In 2021, the Swedish transmission system operator(TSO) Svenska Kraftnät paid out over SEK 2 billion to actors in the ancillary service market and they are expecting it to grow even more.


A basic prerequisite for the electricity system to function and deliver electricity is that there exist a balance between production and consumption – every second. If not, the frequency is disturbed which, in the worst case, can lead to technical equipment getting damaged or destroyed. Ancillary services aimed at managing frequency deviations and ensuring that there is a balance are increasing greatly.

In January 2022, a new ancillary service, FCR-D down(downward Frequency Containment Reserve Disturbance), was started, it was created to help the power grid lower its frequency when it deviates above 50,1 Hz. The TSO pays suppliers of FCR-D down to be put in stand by incase they need to temporarily reduce or increase their energy production. It makes it possible for the TSO to reduce the production from, a wind farm as an example, to 50 percent within 5 second and to 100 percent within 30.

Svenska kraftnät assesses that, as a result of the increased supply of renewable energy, it will become more common in the future with disturbances causing the frequency to deviate above 50,1 Hz.

– The large expansion of wind power affects the stability of the power system, the reason is that the production is both difficult to predict and is also connected via power electronics. This means that the power system becomes more unstable due to fluctuations in production and that it does not contribute to the system inertia as, for example, direct-connected production does, says Jorunn Cardell who is power system analyst at Svenska kraftnät.

– These disturbances are becoming more and more common when, for example, we get more HVDC cables that can create disturbances when exporting electricity, or if facilities with a high consumption, which are also becoming more common, are unexpectedly disconnected from the grid. In these situations, among other things, support services that are part of the FCR-D Down market step in and provide support, explain Cardell.

Sidensjö highlights the importance of the collaboration between the different partners in the project.

We are very happy about the successful implementation of the project. We would therefore like to thank everyone involved in the project for the excellent work. In addition to Entelios, Siemens Gamesa Renewable Energy AB and our operations manager RES Renewable Norden AB were particularly responsible for the success of the project. As a producer of renewable electricity, we are also pleased to be able to make an active contribution to grid stability in Sweden, says Roman Dialer, who is Board Director of Sidensjö Vindkraft AB

In addition, to FCR-D Down contributing with supporting and stabilizing the power system, another dimension is also brought up.

– It is a fact that unregulated and weather-dependent production causes difficulties in maintaining the balance. A support service like FCR-D Down is therefore a central tool for getting more renewable energy into the system, says Mattias Harrysson, who is Head of Energy & Sustainability Services at Entelios Nordic.

Harrysson adds that there is a clear driving force among wind power producers to be at the forefront and drive development forward. – Many wind farm owners are positive towards the opportunity to participate on the FCR-D down market as it helps to solve a problem of which their own businesses are a part of. They are clearly taking a big responsibility by influencing current and future requirements and lead the work to be able to adapt to the requirements for wind power resources. The profitability of running a wind farm also increases as the wind farm owner receives compensation for deliveries to ancillary services, says Harrysson.

In the project, Entelios has an overall project management role to ensure clear and effective communication between the various actors in the project, such as the turbine supplier, park manager and subcontractors of IT services. Entelios also has the closest contact with Svenska kraftnät, especially in connection with the pilot study that Sidensjö is involved in “Delivery of support services from resources with variable production or consumption”. Entelios is also responsible for bidding, communication with Svenska kraftnät, reporting of data and invoicing.