
286 Engineering Response to Climate Change
dispatched to increase the frequency. Spinning reserves are provided
by rotating generators that are already providing power to the grid,
but not at their maximum power level; thus, they can ramp their
power output up in a matter of minutes. Spinning reserves may be
supplemented by nonspinning reserves that can be started and syn-
chronized to the grid within 10 min. To bring the frequency back to
60Hz, slower starting secondary reserves are manually dispatched
once it is determined that a contingency has occurred. With frequency
restored and stabilized at 60 Hz, tertiary reserves are dispatched to ...