What makes up spinning reserves in a power system?

Spinning reserves in a power system are primarily made up of generators that are online and producing power but are not operating at their maximum output capacity. These generators can quickly ramp up their output to respond to sudden increases in demand or unexpected outages in other generating units. This capability is crucial for maintaining the stability and reliability of the power grid, as it allows the system to meet changes in energy demand without interruption.

While synchronous condensers play a role in voltage support and can provide reactive power, they do not contribute to the generation of real power needed for spinning reserves. Similarly, capacitors and reactors are used for reactive power management and voltage control but do not provide the real power needed to supply spinning reserves. Therefore, the correct understanding centers on the role of generators as the primary component that constitutes spinning reserves, enabling quick responsiveness to power system needs.