NEMPulse · Glossary · FCAS

Contingency FCAS

Name: NEM Grid-Scale Battery Dispatch & Revenue Data
Creator: NEMPulse
License: https://creativecommons.org/licenses/by/4.0/

Fast-response FCAS markets (6-second, 60-second, 5-minute raise and lower) that activate during sudden frequency deviations.

Contingency FCAS are the fast-response frequency services AEMO calls on when the grid suffers a sudden, unexpected event — a large generator tripping offline, a transmission line failing, or a big block of load disconnecting. There are six contingency markets: a raise and a lower service at each of three timeframes — 6-second (fast), 60-second (slow) and 5-minute (delayed) — reflecting how quickly the response must arrive and how long it must be sustained.

Unlike regulation FCAS, contingency services are not called continuously; a provider is paid to hold the capacity in reserve and is only physically dispatched when a contingency actually occurs. Batteries dominate the contingency markets because they can inject or absorb their full rated power within milliseconds, far faster than the thermal plant that historically provided these services. Most NEM batteries sit enabled in one or more contingency markets almost continuously, which is why FCAS enablement alone is a weak signal of strategy — see FCAS Capacity Reserved for the measure NEMPulse uses instead.