In order to ensure the balance between production and demand, the Overall System Management (GGS), in accordance with the Overall System Management Procedures Manual,
has at his disposal three types of reserve:
Primary Regulation Reserve: Action of the turbine speed regulator due to a shift of the electrical system's frequency,
with the aim of adjusting the power of the generator group. The resulting power variation should take place within 15 seconds
in relation to disruptions which cause frequency shifts of less than 100 mHz and linearly between 15 and 30 seconds
for frequency shifts of 100 to 200 mHz.
The aim of the Secondary Regulation Reserve is to control the shifts in the interconnection programme
with Spain, to collaborate in maintaining the joint frequency, or, in the event of island operation,
to control the system's frequency shift with regard to the nominal frequency. The activation of the
Secondary Reserve should not take more than 30 seconds and its action should be concluded -
and eventually completed by the action of the tertiary regulation, in the event of the
loss of an important generator group, - within a maximum of 5 minutes.
Regulating Reserve: The maximum positive or negative power variation in system groups
which can be used within the current operation programming period. Whenever the previewed
production in the last programme is different from the GGS demand forecast, a mobilization
or demobilization of production/consumption in the Balance Areas will be instructed in order
to balance production with the referred demand, meeting the minimum reserve requirements.