Integrating Southwest Power Pool Wind to Southeast Electricity ...

Unit Startups
Changing the balancing strategy can change the number of starts for units. The cost of cycling
and ramping on conventional generation in terms of effect on forced outage rate, maintenance
costs and heat rate degradation is not studied here (and is in fact not well understood in general at
present). As such, the effect of wind on cycling can only be seen from the UPLAN production
cost model results in how it changes the number of start/stop operations of units. More cycling
operation would likely result in more breakdowns, maintenance scheduling and possibly early
retirement, therefore strategies that reduce this will be beneficial, in particular for coal or older
CC units.
Figure 5-22 shows the average number of starts per year by unit type for each region. Note that
these starts are not necessarily attributable to wind variability as normal load cycling and forced
or unforced outages also drive some portion of the starts. Increased levels of wind, however,
will increase the cycling of the units. Given that the data in Figure 5-22 compares scenarios all
with 48 GW of wind, the differences between scenarios indicates how balancing cooperation
strategies impact cycling. Only CC and coal are shown as these are the units not specifically
designed to start and ramp as frequently as GTs would be. In addition, coal in Entergy is not
shown as starts do not change. As expected, coal units, which have larger start costs and times
and longer minimum up times, do not cycle on and off significantly.
Figure 5-22
Average number of starts by unit type
Table 5-13 shows the average number of starts per unit of each type per year for Scenario #1 and
the change in the number of starts for each of the other scenarios relative to Scenario 1 with a
positive value indicating an increase in starts versus scenario 1. In addition to the high wind
transfer case scenarios, the low wind case of 14 GW with unconstrained transmission is shown
for comparison of how the additional 34 GW of wind impacts unit starts. The additional 34 GW
of wind generally results in more starts in the SERC regions as more cheap and variable energy
is available, but the numbers are not as dramatic as might be expected. CC units in Entergy and
TVA cycle off on average 25 and 16 times more per unit per year in the high wind case,
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