A load following ancillary service (LFAS) is the power system security ancillary service whereby assigned generators automatically and constantly change their output to compensate for load and wind fluctuations and thus regulate the system frequency.

Load following units will respond automatically to any over or under frequency events (including generator trips and load rejection events).

System Management issued an Expression of Interest (EOI) to Independent Power Producers (IPPs) in 2010 for load following. The requirements on generators identified for LFAS in the new competitive market have been based on this earlier EOI, and include requirements on governor and control systems (connection to automatic generation control (AGC)) as well as (fast) ramp rate requirements.

For more information, please refer to the Ancillary Services Power System Operating Procedure.