The term ancillary services is used to refer to a variety of operations beyond generation and transmission that are required to maintain grid stability and security.
Traditionally, ancillary services have been provided by large production units such as synchronous generators.
Spinning reserves are generators that are already online and can rapidly increase their power output to meet fast changes in demand.
Spinning reserves are required because demand can vary on short timescales and rapid response is needed.
[6] Wind turbines with variable-speed generators have the potential to add synthetic inertia to the grid and assist in frequency control.
[7][8][9] CAISO tested the 131 MW Tule wind farm's synchronverter in 2018, and found it could perform some of the grid services similar or better than traditional generators.
[10][11] Hydro-Québec began requiring synthetic inertia in 2005 as the first grid operator, demanding a temporary 6% power boost when countering frequency drop by combining the power electronics with the rotational inertia of a wind turbine rotor.
[13] Plug-in electric vehicles have the potential to be utilized to provide ancillary services to the grid, specifically load regulation and spinning reserves.
Plug-in electric vehicles can behave like distributed energy storage and have the potential to discharge power back to the grid through bidirectional flow, referred to as vehicle-to-grid (V2G).
Plug-in electric vehicles have the ability to supply power at a fast rate which enables them to be used like spinning reserves and provide grid stability with the increased use of intermittent generation such as wind and solar.
According to the study cited in the reference,[14] which compared the profitability of offering operating reserve ancillary service with the sales of V2G energy from a fleet of vehicles, providing operating reserve regulation service is more profitable than selling V2G energy alone.
However, the technologies to utilize electric vehicles to provide ancillary services are not yet widely implemented, but there is much anticipation of their potential.