Pump Schedule Rule

A Pump Schedule rule is an operation rule that specifies the pumping schedule and requirements for a pump outlet. Unlike other outlet types, pump outlets will not "move water" without a rule, and that rule is the Pump Schedule rule.

A Pump outlet provides a reservoir with the ability to pump water from a downstream reservoir into the current reservoir (i.e., pumpback storage operation). This means that the flow direction for water moving through a Pump is opposite to the flow direction of any other outlet; a Pump moves water into the current reservoir while all other outlets move water out of the current reservoir.

The Pump Schedule rule type is only available when a Pump outlet is selected as the release element in the Operates Release From selector; and, it is the only rule type that can be applied to a Pump.

The Pump Schedule Rule editor is shown in "Figure: Pump Rule Editor". The Pump Schedule rule has a number of options and attributes, which are described below; pay careful attention to the description of each option and attribute to learn how each selection you make could change what appears in the editor and how it will affect the way the pump operates.

Note: each zone in the list of zones shown in the Zone selector is identified by its name and the operation set it is defined in. Select the zone associated with the current operation set. Unfortunately, this will make the rule applicable to only to the current operation set. If the same rule is needed in a different operation set, you should re-create the rule and select the appropriate zone for that operation set.

• Target Fill Elevation—the pump operation needs to know why it should pump. The why is the Target Fill Elevation. When the Pump Schedule rule is evaluated, its first determination is whether the reservoir pool is below the target elevation. If so, then the rule decides it needs to pump and proceeds to determine if it is allowed to pump and how much it should pump.

  • Option—there are three options ("Figure: Pump Rule Editor - Target Fill Elevation Options") for specifying the Target Fill Elevation. Each option will change the lower portion of the Target Fill Elevation section of the rule editor as you will see below.
    

    Figure: Pump Rule Editor - Target Fill Elevation Options

    
    
    • Constant—if selected, a Target Elevation text field will be displayed in the lower portion of the Target Fill Elevation section. Enter an elevation above which the reservoir should not pump.

    • Storage Zone—if selected, a Zone selector will be displayed ("Figure: Pump Rule Editor - Target Fill Elevation Option - Storage Zone"). Choose the zone whose top of zone curve represents FULL for the current reservoir.
      

      Figure: Pump Rule Editor - Target Fill Elevation Option - Storage Zone

      
      

    • Seasonally Varying—if selected, a seasonal table relating the Target Fill Elevation to a Date or season will be displayed ("Figure: Pump Rule Editor - Target Fill Elevation Option - Seasonally Varying"). Enter the data to define the seasonally varying target fill elevation in the table.
      

      Figure: Pump Rule Editor - Target Fill Elevation Option - Seasonally Varying

      
      

  • Daily Pumping Period—This is the schedule for which the rule gets its name. Since pumps often run only at night when the power to run them is less expensive, a schedule identifying the pumping window is necessary. In this table you must specify the portion of the day during which pumping is allowed. This is a seasonal table that should start on 01Jan, like all other seasonal tables. You have two options for defining the Daily Pumping Period:

    • Fixed Hour Range—This option displays a seasonal table in which you must enter the start date of each season, the Begin and End times of that season's pumping window, and the number of pump units that may be used. The times must be entered as times on a 24-hour clock and may cross over midnight. For example, to specify a pumping period starting at 9:00 pm and ending at 3:30 am, enter 2100 and 0330 into the Begin and End columns, respectively. The data in each row of the schedule table is treated as a step function and remains in effect until the start of the next season.
      Between Sunset and Sunrise—If selected, this option displays a seasonal table in which you must define the start and end times of the pumping window for each season as a number of hours after sunset and before sunrise (After SS & Before SR), respectively. In order for this schedule to determine when sunrise and sunset occur on any particular day, you are required to provide the approximate Latitude and Longitude of the dam. Note, blank entries for Latitude and Longitude will be translated as 0 values.

• Pumping Strategy—The pumping strategy identifies how and when the pumps are to be used during the pumping window, assuming that there is more time available than is needed to get the reservoir to its target elevation. Your options are:

  • Use full pump capacity—This strategy will minimize the time spent pumping. With this option, you must select the Pumping Bias. Your options include:

    • Beginning of Period—The pumps will start pumping at the beginning of the pumping window.

    • Middle of Period—The hours needed to pump to get the reservoir to the target elevation will be centered within the pumping window.

    • End of Period—the hours needed to pump will be pushed toward the end of the pumping window.

  • Use entire pump period: This strategy will run the pumps at a rate which may be less than full capacity in order to just reach the target at the end of the pumping period.
    Regardless of your Pumping Strategy selection, if the target cannot be reached in the pumping period, the pumps will be operated at full capacity over the entire pumping period in order to get the reservoir elevation as close as possible to the target.
    • Identify the Source Reservoir. This should be the next reservoir downstream of the current reservoir although it may be a reservoir connected to the current one through a diverted outlet. ResSim's pump outlets are designed to only pump from a storage pool, not directly from a stream. NOTE: This field should be defined in the physical data of the pump outlet, not in the operation rule—so don't be surprised if this setting gets moved to where it belongs in a future version of ResSim.
    • Determine if Whole Hour Pumping should be activated. When checked, if the pumps needed to run for a fraction of an hour, then they will run for the full hour, even if their pumping causes the reservoir to exceed the target pool elevation. Note—ResSim really doesn't want to run the pumps longer than necessary, so if it can, it will minimize the total number of pump hours. For example, if you have 2 available pumps and the number of pump unit hours needed to get the reservoir to target is 4.5, then the pumps will only run for a total of 5 pump unit hours—one pump will run for 3 hours and the other for 2 hours (or just one pump for 5 hours).
    • Select the Minimum Pumping requirement. Depending on your selection, this feature identifies the minimum number of hours the pumps must run—if they turn on at all during the pumping window. Your options include:
      • No Required Min—The default. The pumps will only operate if and for how long they need to in order to get the reservoir pool elevation back up to the target within the pumping window.

      • At Least Min—The pumps will operate for at least the specified minimum duration even if the target elevation has been reached or exceeded.  With this option, you must enter a value in the Min. Pump Unit Hrs field. 
        Pump unit hours are the number of hours a single unit operates.  If you have 4 pump units and you want all four pumps to operate for at least 1 hour each during the pump window, you might enter 4 in the Min. Pump Unit Hrs field.  ResSim, however, probably won’t interpret your entry as a requirement to run all four pumps.  It may turn on just one pump and run it for four hours.

      • At Least Min if blw Target—With this option, the pumps will only operate if the reservoir is below the target elevation at the start of the pumping window.  And, if they do operate, they will run for at least the specified duration.  With this option, you must enter a value in the Min. Pump Unit Hrs field.

      • Only if Req’d >= Min—With this option, the pumps will operate only if the time needed to pump (at maximum capacity) is greater than or equal to the specified minimum.  In other words, if the time needed is less than the min, don’t pump. With this option, you must enter a value in the Min. Pump Unit Hrs field.