Probabilistic Frequency Assessment.
How many hours fall below the inertia floor, and which zones cause them?
PFA takes a market dispatch, works out system inertia hour by hour and checks it against the inertia, frequency-response and RoCoF limits over several years. Then it shows where on the network the shortfall sits.
Why it matters nowInertia is falling just as single connections get bigger: a gigawatt data centre or interconnector is a gigawatt loss risk. PFA checks the system rides through the worst credible loss.
How PFA works.
- 01
Stochastic profile
Ingests the market dispatch and computes system inertia hour by hour.
- 02
Five components
DG, transmission generation, demand, base and total, each plotted separately.
- 03
Three limit checks
Inertia floor, frequency-response shortfall and RoCoF (Hz/s) screened across all hours.
- 04
Zonal layer
Maps the inertia gap onto the network and ranks the best mitigation sites.
A year of inertia, hour by hour.
Total system inertia across the year against the statutory inertia limit and RoCoF floor. Every hour beneath the line is a security exposure to be priced and located.
Figures from an example run on a test network.
A handful of zones account for most of the hours below the floor. PFA flags the best synchronous condenser and grid-forming sites, ranked by electrical distance to the deficit.