Battery knowledge · Applications and market
Rate of change of frequency
How fast grid frequency moves after a sudden imbalance such as a large generator tripping. Grids with less rotating inertia see steeper slopes; Great Britain has relaxed its loss-of-mains protection settings from 0.125 Hz/s to 0.5–1 Hz/s. Fast battery response and grid-forming inverters that emulate inertia help keep it within limits.
- Abbreviation
- RoCoF
- Unit
- Hz/s
- Relationship
- RoCoF = df/dt
Example
Measure a frequency slope
If measured grid frequency falls from 50.0 Hz to 49.8 Hz over 0.5 s, the average RoCoF is −0.4 Hz/s. Reporting windows and filtering affect the observed value.
Explore the graph
A linear frequency segment has a constant rate of change.
The selected slope is -0.5 Hz/s; after 2 s the authored frequency is 49 Hz.
RoCoF = df/dt
Illustrative model. A short illustrative line, not a power-system response or protection-setting recommendation.
Use in Lemonergy
Start with mission energy, peak power and operating conditions.
This is a reference concept. No executable Lemonergy block has been verified for this term.
References & further reading
Further reading on this topic
These sources provide broader context; they are not presented as citations for every statement in this entry.
- DOE/EPRI 2013 Electricity Storage Handbook in Collaboration with NRECA
Sandia National Laboratories · 2013
Topic background · Storage technologies and grid services. The publisher notes that its historical cost and deployment figures are outdated.