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Objects and Methods : Level Power Reservoir : User Methods : Load Calculation
Load Calculation
When the Meet Hydropower Load method is selected, a category called Load Calculation becomes visible. In this category there are seven methods: None, Input Load, Annual Load, Monthly Load, Periodic Load, Seasonal Load and Seasonal Load Time. Most of the selected method in this category are executed at the beginning of each timestep so that the method is only called once per timestep but the information on the state of the system is available (such as previous Pool Elevation) to the method. Input Load and Seasonal Load time are not called at the beginning of the timestep as Input Load doesn’t have any computations and Seasonal Load Time is executed as described below. Below is a description of each method.
* None
This is the default method and has no slots associated with it. If this method is selected, an error is issued saying “Cannot find a selected method in the Load Calculation category.”
* Input Load
If this method is selected, the Load must be input or specified with a rule. If not valid, the run terminates with an error.
Slots Specific to This Method
 Load
Type: Series Slot
Units: energy
Description: The desired energy that the power reservoir should produce
Information:  
I/O: Required input or set by a rule
 Dump Energy
Type: Series Slot
Units: Energy
Description: The exceed energy produced during the timestep.
Information: Calculated as Max(0, Energy - Load) at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
 Thermal Purchase
Type: Series Slot
Units: Energy
Description: Energy shortage for the given timestep. It is the amount of additional energy that would be required to fully meet the Load
Information: Calculated as max (0, Load - Energy) at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
 Operation Factor
Type: Series Slot
Units: Decimal
Description: The fraction of the timestep at which the turbines are running
Information: Calculated as Peak Time / Timestep Length. This is done at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
* Annual Load
For the Annual Load method, the user provides the load values for each year of the run and a set of weekday and weekend monthly factors used to disaggregate the annual load to daily values.
Slots Specific to This Method
 Annual Load
Type: Series Slot
Units: energy
Description: The load for each year of the run.
Information: The user must set the timestep for this series slot to be 1 Year. See the example in the table below.
Note: Because this slot is annual, it is most likely different than the run timestep. As a result, if the user desires to synchronize objects, the user must select the toggle in the synchronization control to Exclude Slots with Different Timestep from Run. This will prevent changing the timestep of this slot when other slots are synchronized.
I/O: Input only
 Load
Type: Series Slot
Units: energy
Description: The desired energy that the power reservoir should produce
Information: The load value is either a user input or set by a method in the Load Calculation category
I/O: Input or set by the method
 Load Factor
Type: Periodic Slot
Units: none
Description: The factors used to disaggregate the yearly load to daily load
Information: The periodic slot contains a value for each month of the year. The first data column is the multiplying factor to disaggregate the annual load to a daily value for weekdays. The second data column contains the disaggregating factors for weekends. See the sample slots in the following table.
I/O: Input only
 
Annual Load
 
Load Factor
Month
Load (KWH)
 
Date
Weekday Load Factor
Weekend Load Factor
24:00 Dec 31, 1954
10,000
 
January 1
.041
0
24:00 Dec 31, 1955
11,000
 
February 1
.041
0
24:00 Dec 31, 1956
12,000
 
March 1
.083
.041
...
...
 
...
...
...
 Dump Energy
Type: Series Slot
Units: Energy
Description: The exceed energy produced during the timestep.
Information: Calculated as Max(0, Energy - Load) at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
 Thermal Purchase
Type: Series Slot
Units: Energy
Description: Energy shortage for the given timestep. It is the amount of additional energy that would be required to fully meet the Load
Information: Calculated as max (0, Load - Energy) at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
 Operation Factor
Type: Series Slot
Units: Decimal
Description: The fraction of the timestep at which the turbines are running
Information: Calculated as Peak Time / Timestep Length. This is done at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
* Monthly Load
For the Monthly Load method, the user provides the load values for each month of the run and a set of weekday and weekend monthly factors used to disaggregate the monthly values to daily values. The monthly load value is multiplied by the either the weekend or weekday factor and then divided by the number of weekdays or weekend days in the given month as applicable.
Slots Specific to This Method
 Load
Type: Series Slot
Units: energy
Description: The desired energy that the power reservoir should produce
Information: The load value is either a user input or set by a method in the Load Calculation category
I/O: Input or set by the method
 Load Factor
Type: Periodic Slot
Units: none
Description: The factors used to disaggregate the monthly load to daily load
Information: The periodic slot contains a value for each month of the year. The first data column is the multiplying factor to disaggregate the monthly load to a daily value for weekdays. The second data column contains the disaggregating factors for weekends. See the example below.
I/O: Input only
 Monthly Load
Type: Series Slot
Units: energy
Description: The load for each month of the run.
Information: The user must set the timestep for this series slot to be 1 Month. See the sample slots in the table below. Because this slot’s timestep is 1 Month, it is most likely different than the run timestep. As a result, if the user desires to synchronize objects, the user must select the toggle in the synchronization control to Exclude Slots with Different Timestep from Run. This will prevent changing the timestep of this slot when other slots are synchronized.
I/O: Input only
 
Monthly Load
 
Load Factor
Month
Load (GWH)
 
Date
Weekday
Load Factor
Weekend
Load Factor
24:00 Jan 31, 1940
1.71
 
January 1
1
0
24:00 Feb 28, 1940
1.56
 
February 1
1
0
24:00 Mar 31, 1940
1.72
 
March 1
.9
.1
...
...
 
...
...
...
 Dump Energy
Type: Series Slot
Units: Energy
Description: The exceed energy produced during the timestep.
Information: Calculated as Max(0, Energy - Load) at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
 Thermal Purchase
Type: Series Slot
Units: Energy
Description: Energy shortage for the given timestep. It is the amount of additional energy that would be required to fully meet the Load
Information: Calculated as max (0, Load - Energy) at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
 Operation Factor
Type: Series Slot
Units: Decimal
Description: The fraction of the timestep at which the turbines are running
Information: Calculated as Peak Time / Timestep Length. This is done at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
* Periodic Load
For the Periodic Load method, the user provides a periodic slot that contains the load for both weekday and weekend days. During the run, the load is looked up from this slot.
Slots Specific to This Method
 Load
Type: Series Slot
Units: energy
Description: The desired energy that the power reservoir should produce
Information: The load value is either a user input or set by a method in the Load Calculation category
I/O: Input or set by the method
 Periodic Load
Type: Periodic Slot
Units: time vs energy and energy
Description: A periodic slot containing the load in units of Energy to be used for the run.
Information: The slot consists of two columns, one column for the weekday values, one for the weekend values. See the sample slots in the table below.
I/O: Input only
 
Date
Weekday Load (KWH)
Weekend Load (KWH)
January 1
100
20
February 1
120
30
March 1
120
20
 Dump Energy
Type: Series Slot
Units: Energy
Description: The exceed energy produced during the timestep.
Information: Calculated as Max(0, Energy - Load) at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
 Thermal Purchase
Type: Series Slot
Units: Energy
Description: Energy shortage for the given timestep. It is the amount of additional energy that would be required to fully meet the Load
Information: Calculated as max (0, Load - Energy) at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
 Operation Factor
Type: Series Slot
Units: Decimal
Description: The fraction of the timestep at which the turbines are running
Information: Calculated as Peak Time / Timestep Length. This is done at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
The method looks up the current date in the date column of the table and sets the value from the appropriate column on the Load slot.
* Seasonal Load
For the Seasonal Load method, the user provides two three-dimensional periodic slots that contain the load for weekdays and weekends. During the run, the Load is looked up from the appropriate slot.
Slots Specific to This Method
 Load
Type: Series Slot
Units: energy
Description: The desired energy that the power reservoir should produce
Information: The load value is either a user input or set by a method in the Load Calculation category
I/O: Input or set by the method
 Seasonal Weekday Load
Type: Periodic Slot
Units: time vs energy vs length
Description: A periodic slot containing the date, column headings containing the energy load, and values in the table representing pool elevations
Information: The first column contains the date. The remaining columns represent the load in increasing order. The values in the table represent the pool elevations. See the example in the table below.
I/O: Input only
 Seasonal Weekend Load
Type: Periodic Slot
Units: time vs energy vs length
Description: A periodic slot containing the date, column headings containing the energy load, and values in the table representing pool elevations
Information: The first column contains the date. The remaining columns represent the load in increasing order. See the sample slots in the table below; the values represent the pool elevations.
I/O: Input only
 
 
Load (MWH)
Date
100
200
300
400
January 1
5550 [ft]
5558
5565
5590
February 1
5550
5558
5565
5590
March 1
5550
5552
5560
5580
...
...
...
...
...
 Dump Energy
Type: Series Slot
Units: Energy
Description: The exceed energy produced during the timestep.
Information: Calculated as Max(0, Energy - Load) at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
 Thermal Purchase
Type: Series Slot
Units: Energy
Description: Energy shortage for the given timestep. It is the amount of additional energy that would be required to fully meet the Load
Information: Calculated as max (0, Load - Energy) at the end of the Peak Power Equation with Off Peak Spill power method power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
 Operation Factor
Type: Series Slot
Units: Decimal
Description: The fraction of the timestep at which the turbines are running
Information: Calculated as Peak Time / Timestep Length. This is done at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
Method Details 
This method uses the following process.
1. Selects the appropriate periodic slot, depending on the type of day.
2. Looks up the day of year in the first column, and the previous pool elevation in the column header.
3. Uses the value in the table for the energy.
4. Writes the load to the Load slot. As is typical with periodic slots, the time range, number of columns, and interpolation/lookup configuration can be changed.
* Seasonal Load Time
For the Seasonal Load Time method, the user provides two three-dimensional periodic slots that contain the fraction of a timestep that the turbines should operate for weekdays and weekends.
Slots Specific to This Method
 Load
Type: Series Slot
Units: energy
Description: The desired energy that the power reservoir should produce
Information: For this method, the Load is set by a rule using the HydropowerRelease predefined function; see “HydropowerRelease” in RiverWare Policy Language (RPL).
I/O: Output only - Set by a rule. It cannot be input or it may cause the HydropowerRelease rule to fail giving unexpected results.
 Load Time
Type: Series Slot
Units: time
Description: The desired time that the reservoir should operate at full turbine capacity
Information: The Load Time is the appropriate Seasonal Weekday (or Weekend) Load Fraction value multiplied by the Length. This is done of the timestep.
I/O: Output only
 Seasonal Weekday Load Fraction
Type: Periodic Slot
Units: time vs fraction vs length
Description: A periodic slot containing the date, column headings containing the fraction of timestep, and values in the table representing pool elevations
Information: The first column contains the date. The remaining columns represent the fraction of timestep in increasing order. The values in the table represent the pool elevations. The column headings can be configured to be either decimal (0-1) or percentages (0-100%). See the example in table below.
I/O: Input only
 Seasonal Weekend Load Fraction
Type: Periodic Slot
Units: time vs fraction vs length
Description: A periodic slot containing the date, column headings containing the fraction of timestep, and values in the table representing pool elevations
Information: The first column contains the date. The remaining columns represent the fraction of timestep in increasing order. The values in the table represent the pool elevations. The column headings can be configured to be either decimal (0-1) or percentages (0-100%). See the example in the table below.
I/O: Input only
 
 
Fraction of Timestep [%]
Date
10
20
30
40
January 1
5550 [ft]
5558
5565
5590
February 1
5550
5558
5565
5590
March 1
5550
5552
5560
5580
...
...
...
...
...
 Dump Energy
Type: Series Slot
Units: Energy
Description: The exceed energy produced during the timestep.
Information: Calculated as Max(0, Energy - Load). If this method is selected, Load is not known until set by the rule calling the HydropowerRelease function. Therefore, for this method only, Dump Energy is calculated at the end of the timestep. It is not available to be accessed by other rules at the current timestep.
I/O: Output only
 Thermal Purchase
Type: Series Slot
Units: Energy
Description: Energy shortage for the given timestep. It is the amount of additional energy that would be required to fully meet the Load
Information: Calculated as max (0, Load - Energy). If this method is selected, Load is not known until set by the rule calling the HydropowerRelease function. Therefore, for this method only, Thermal Purchase is calculated at the end of the timestep. It is not available to be accessed by other rules at the current timestep.
I/O: Output only
 Operation Factor
Type: Series Slot
Units: Decimal
Description: The fraction of the timestep at which the turbines are running
Information: Calculated as Peak Time / Timestep Length. This is done at the end of the Peak Power Equation with Off Peak Spill power method; see “Peak Power Equation with Off Peak Spill”.
I/O: Output only
Method Details 
This method uses the following process.
1. Selects the appropriate periodic slot, depending on the day of week.
2. Looks up the timestep in the first column, and the previous pool elevation in the table.
3. Uses the value in the column heading for the fraction of timestep.
4. Calculates Load Time as the fraction of timestep times the timestep length. As is typical with periodic slots, the time range, number of columns, and interpolation/lookup configuration can be changed.
In this method, the Load value is determined by the method, but it is not set until the rule calling the Hydropower Release function completes execution. This is different from the other methods in the Load Calculation category. A special function call determines the energy produced if the reservoir is run at generator capacity for the Load Time. This energy is equivalent to the Load, and it is used in all subsequent calculations where Load is required.
Revised: 11/11/2019