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Power Plant Diversion
Objects and Methods
Power Plant Diversion
The Power Plant is a collection of individual Generators (see “Generator” for details). A single diversion is used to serve all generators in the plant. Thus, the plant level computations divert water from a reach or reservoir to meet the Total Diversion Requested limited by the Total Available Water. The plant also computes the depletion and consumption of water and diversion and depletion shortage. If there is a shortage, then there is no need to allocate that shortage to individual generators. Figure 21.1 is an illustration.
Figure 21.1  Common linking structure of the Power Plant Diversion, Generators and reach/reservoir
The individual Generator requests are summed in the Total Diversion Requested slot on the Power Plant Diversion.
Note:  It is not required to use Generator elements with this linking structure. If desired, Total Diversion Requested and Total Depletion Requested can be input directly by the user. However, it is often desirable to use one or more Generator objects for this purpose.
There are no user methods for this object.
General Slots
Total Available Water
Type: Series Slot
Units: FLOW
Description: signifies the water available for diversion from the reservoir or reach to which the diversion is connected
Information: Set by link propagation from the diverted object. The user is responsible for linking this slot with the object from which the water is diverted.
I/O: Optional; Could be input if not set via link.
Total Depletion
Type: Series Slot
Units: FLOW
Description: The total amount consumed.
Information: Computed typically as Total Diversion minus Total Return Flow
I/O: Output only
Total Depletion Requested
Type: Multislot
Units: FLOW
Description: a multislot showing the Depletion Requested for each Generator as well as the sum of all requested depletions.
Information:  
I/O: Optional; Can be input when there are no Generator elements and it is not linked.
Total Diversion
Type: Series Slot
Units: FLOW
Description: Denotes the total water diverted to the Water Users
Information:  
I/O: Optional; must be specified if Total Diversion Requested is not given.
Total Diversion Requested
Type: MultiSlot
Units: FLOW
Description: a multislot showing the Diversion Requested for each Generator as well as the sum of all requested diversions.
I/O: Optional; Can be input when there are no Generator elements and it is not linked.
Total Return Flow
Type: Series Slot
Units: FLOW
Description: represents the portion of the water diverted which is not consumed
Information: It is the user’s responsibility to specify what is done with this data. If it is not linked to another object (i.e. back to the reach/reservoir Return Flow slot), it is lost from the system.
I/O: Output only
Total Depletion Shortage
Type: Series Slot
Units: Flow
Description: Represents the difference between Total Depletion Requested and Total Depletion.
Information: Computed as Total Depletion Requested - Total Depletion
I/O: Output Only
Total Diversion Shortage
Type: Series
Units: Flow
Description: The difference between Diversion Requested and Diversion
I/O: Output Only
Dispatch Methods
The Power Plant Diversion solves given either diversion requests and available water (most common) or just diversion.
* Solve given Diversion Request and Available
This dispatch method will solve when diversion requests and the available water are known. It computes the total diversion and depletion (consumption).
The Total Diversion Requested is compared with the Total Available Water slot. If the total request can be met, the Total Diversion slot is set to that amount; if not, the Total Diversion slot is set to the Total Available Water amount. If a total deficit occurs in the Diversion, the Return Flows are recalculated based on the ratio of the Total Depletion Requested to the Total Diversion Requested. The Total Depletion Shortage is computed as the difference between Total Depletion Requested and Depletion.
Required Knowns
Required Unknowns
Following is a general description of the interaction among the Power Plant Diversion, Generators, and Reach/Reservoir.
1. Reach/Reservoir Available For Diversion is set.
2. This value propagates to Power Plant Diversion: Total Available Water.
3. Solve given Diversion Request and Available dispatches on the Power Plant Diversion object.
4. Within the dispatch method, Total Diversion and Total Return Flow are calculated.
5. The values propagate to the reach or reservoir and that object re-solves.
The Solve given Diversion Request and Available performs as follows.
1. If Total Depletion Requested is not specified, it is set equal to the Total Diversion Requested.
2. If Total Diversion Requested is greater than or equal to the Total Available Water:
Total Diversion = Total Available Water
3. If the Total Diversion Requested is less than Total Available Water:
– Total Diversion = Total Diversion Requested
– Total Return Flow = Total Diversion - Total Depletion Requested
4. Total Depletion is set as the difference between Total Diversion and Total Return Flow.
5. Total Depletion Shortage is computed as Total Depletion Requested minus Total Depletion.
6. Total Diversion Shortage is computed as Total Diversion Requested minus Total Diversion.
* Solve given Diversion
This dispatch method will solve when diversion is known. It computes the total return flow and depletion (consumption).
Required Knowns
Required Unknowns
The Solve given Diversion dispatch method performs as follows.
1. If Total Diversion Requested is not specified, assume it is equal to Total Diversion. The slot is not set, however.
2. If Total Depletion Requested is not specified, assume it is equal to the Total Diversion Requested, if valid. Otherwise assume it is equal to Total Diversion. The slot is not set, however.
3. If Total Diversion Requested is zero, set Total Return flow equal to Total Diversion minus Total Depletion Requested.
4. Else, if Total Diversion is less than Total Diversion Requested, set the following:
5. Otherwise, Total Diversion is greater than Total Diversion Requested. Set Total Return Flow equal to Total Diversion minus Total Depletion Requested.
6. Then, Total Depletion is set as the difference between Total Diversion and Total Return Flow.
7. Total Depletion Shortage is computed as Total Depletion Requested minus Total Depletion.
8. Total Diversion Shortage is computed as Total Diversion Requested minus Total Diversion.
 
Revised: 06/03/2019