PlayableFCR-D upward60 seconds
Hold 50 Hz
You are a grid battery in the Nordic synchronous area. Demand wanders, and twice during the next minute the largest unit on the system trips offline. Your job is to keep frequency inside the band. You will not manage it, and the margin by which you fail is the entire reason this service is worth paying for.
Nordic synchronous area · system frequency
50.00 Hz
Your output0 MW
Hold ↑ to inject power, ↓ to absorb. Or press and hold the buttons.
You
Battery, dynamic
0.5 s
Static provider
5.0 s
Hydro governor
30 s
Why you lost
Human reaction to a visual signal is roughly 250 milliseconds before you have moved anything. FCR-D requires half of the contracted capacity delivered within five seconds and all of it within thirty. A grid battery gets to full output in well under a second, and it does it every time, at three in the morning, without watching.
- The frequency falls fastest at the start. The rate of change depends on how much rotational energy is spinning in the system. Less inertia means a steeper drop and less time to act, which is exactly why the Nordic TSOs are tightening the static limit when inertia is low.
- Overshoot is a real failure. Injecting too much for too long pushes frequency above the band from the other side. The service is not "push hard", it is "push exactly enough and then stop".
- Slow reserves take over after about ten seconds. That is what you are bridging to. FCR-D is not meant to fix the imbalance, only to arrest the fall until something slower arrives.
- This capability is worth less every year. There is now roughly five times more prequalified battery capacity in Sweden than the entire national requirement, against demand that cannot grow by construction.