Time-averaging period for regulation service

Because electricity is a real-time product, power system operators must adjust generation to match load on a moment-to-moment basis, providing the ancillary service called regulation. But what is meant by moment-to-moment? This article addresses that question by providing background information on the regulation ancillary service and by analyzing short-interval changes in system-level generation and load for four electrical systems. Three systems are large, with peak demands between 10,000 and 20,000 MW, while the fourth system has a peak demand of under 5,000 MW. One of the large systems relies primarily on hydro units for regulation, while the other three systems use fossil units. For each system, the authors obtained 30-second data for 1 or more days on total generation and load. They analyzed these data to see how quickly and with how much lag generation follows load.