Outage Scale Method Column
This column offers various options for scaling forced or maintenance outages across segments of a unit.
To illustrate the various options, assume a unit with 100 MW of capacity, a Min Capacity of 30% (or 30 MW), 7 other segments defined at 10 MW each and a Forced Outage (FOR) of 10%.
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TopDown will apply outages directly to the top (most expensive) segment, and continue down each segment until the unit total outage level has been reached.
In the example unit, segment 8 (top) would have 0 capability, segments 2-7 would all have 10 MW, and the Minimum Segment would have 30 MW. If it had been an FOR of 15%, then, again, segment 8 (top) would have 0 capability, segment 7 (next) would have 5 MW capability, segments 2-6 would all have 10 MW, and the min segment would still have 30 MW.
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ScaleExMin will scale outages proportionally across all segments - except the Minimum Segment - such that total unit derate will still be achieved.
In the example unit, 10 MW of reduction in capability is needed (FOR of 10%), but that is applied evenly to segments 2-8. 10 MW / 7 remaining segments = 1.429 MW/segment. Now, segments 2-8 would have 10 – 1.429 = 8.571 MW, and the min segment would still have 30 MW.
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ScaleAll will scale outages proportionally across each segment of the unit.
In the example unit, segments 2-8 would have 10 * (1 – 0.10) = 9 MW, and the min segment would have 30 * (1 – 0.10) = 27 MW.
A blank, null value, or missing column will default to scale outages proportionally across each segment of the unit.
This is especially relevant when using multiple segments defined by the Heat Rate Definitions table.
Outage Scale Method Column
