LOLP for the Year The relationship between the average yearly value for the LOLP and the LOLPs for the individual maintenance intervals is the same as the relationship when there is no SPS in the power pool. However, when the SPS must be taken off-line for maintenance or is shut down because of the effects of the earth eclipses, this must be done explicitly. Those maintenance intervals during which the SPS in not on-line are specified and the LOLPs for those intervals are calculated as if the SPS did not exist. The yearly average LOLP is calculated for several different assumed numbers of conventional machines in the power pool. We assumed that the year was broken into 14 equal maintenance intervals (utilities use 13 maintenance intervals). The average yearly value for the LOLP would be The £th maintenance interval may contain one, two, three, six, or no SPSs. If the LOLP for every interval is just slightly less than .ld/year, then the yearly LOLP is just slightly less than .ld/year. Number of Generators Required in the Power Pool Enough generating capacity must be available during each maintenance interval to meet the LOLP criterion and yet be able to take each machine off-line for scheduled maintenance for the required number of intervals (assumed in this model to be 3 intervals out of
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