Constraint Segment Definition
This option is used for annual Constrained Dispatch studies and defines how the load duration curve (LDC) segments are configured. The annual constraint logic groups together similar dispatch hours for each month into buckets in order to create a manageable problem size for the annual LP to solve. You will have to consider the constraints of your machine. You can also type in a numeric value.
Valid entries are listed below. Each option averages data across the weeks of each month and gives the most differentiation based on hour of the week within the month.
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High creates 36 distinct segments for each month and is generally recommended unless there are significant memory constraints on the machine.
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Medium creates 24 segments.
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Low creates 12 segments.
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[Level]_Weekly. To differentiate with more detail across the different weeks of the month (i.e., If Week 1 of the month should be treated differently than Week 2 of the month), use these entries instead: High_Weekly, Medium_Weekly, Low_Weekly. Generally using the _Weekly type definition gives similar results to the corresponding definition without the _Weekly suffix specification, but it may be useful when data changes significantly across weeks of the month.
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Extreme creates 48 distinct segments, but should be used with caution due to significant use of memory.
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Numeric Value. Any numerical value can be entered, but remember that values above ~36 will create significant memory constraints for most machines. When a direct numeric value is input, Aurora creates that many segments per month and groups them together based on load. This can be entered directly or through a Time Series Reference (as long as it does not resolve to an hourly or weekly vector, which would be interpreted using the method described below). For example, if you want more precision in summer months when load is higher, use a Time Series Monthly reference with a higher numeric value in the summer months.
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Hourly Grouping Reference. Alternately, this setting can also specify which hours should be grouped together by referencing a Time Series Hourly or Time Series Weekly vector. Positive integer values are entered in each of the hours of the referenced hourly/weekly vector.
For example, to inform the LDC to create 24 unique groups, segmented by hour, enter the values 1 through 24 repeated seven times for the seven days in the in a weekly vector for each month. Aurora will then assume that for a given month, hours with the same number are grouped together in the LDC calculations. The operating characteristics such as load, resource costs, transmission limits, etc. will be averaged together across all hours within the same group for when solving the annual LP (e.g. data from hour 1 for all days would be averaged together, etc.).
Nested references (via the Time Series Annual and Time Series Monthly) are also allowed for this method. But again, generally speaking, as more distinct segments are used the constraint logic will be more precise but will also use more memory.
NOTE: For information on how to specify a time series for a variable, see Entering a Time Series.
Constraint Segment Definition