RTC Example

The following example of Real Time Control compares the volume in two tanks and regulates the discharge from these tanks so that a maximum flow is not exceeded.

 

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Under this scenario, the flow in conduit H.1 and the levels in tanks D and I are monitored. The volume in Tank D and Tank I is calculated by use of tables, and the difference between the volumes is calculated by use of a Variable. The orifices on the outlet to Tank D and on the outlet to Tank I are controlled incrementally depending on the magnitude of flow in conduit H.1 and which tank contains greater volume:

• If the flow in conduit H.1 is less than or equal to 0.58 m3/s and the volume in Tank D is greater than the volume in Tank I, the orifice at Tank D will open by an increment of 0.01 m3/s
• If the flow in conduit H.1 is greater than 0.58 m3/s and the volume in Tank I is greater than the volume in Tank D, the orifice at Tank D will close by an increment of 0.01 m3/s
• If the flow in conduit H.1 is less than or equal to 0.58 m3/s and the volume in Tank I is greater than the volume in Tank D, the orifice at Tank I will open by an increment of 0.01 m3/s
• If the flow in conduit H.1 is greater than 0.58 m3/s and the volume in Tank D is greater than the volume in Tank I, the orifice at Tank I will close by an increment of 0.01 m3/s

RTC Scenario Summary

Global dependents

Component	Name	Parameters	Effect
RANGE 1	UPFLOW	Range type: Q -  flow Location Link: H.1 Minimum: 0.000 m3/s Maximum: 0.580 m3/s	TRUE if flow in conduit H.1 is between 0.000 m3/s and 0.580 m3/s
RANGE 2	DOWNFLOW	Range type: Q -  flow Location node: H.1 Minimum: 0.580 m3/s Maximum:	TRUE if flow in conduit H.1 is greater than 0.580 m3/s
RANGE 3	LEVELD	Range type: Z -  Height above datum Location Node: D Minimum: Maximum:	TRUE if Height above datum at Node D is between - / + infinity
RANGE 4	LEVELI	Range type: Z - Height above datum Location Node: I Minimum: Maximum:	TRUE if Height above datum at Node I is between - / + infinity
TABLE 1	STORED	Measurement: Volume Input Range: LEVELD Type: Linear Input/Output grid: Height above datum vs Volume	Relationship between level and volume at Node D
TABLE 2	STOREDI	Measurement: Volume Input Range: LEVELI Type: Linear Input/Output grid: Height above datum vs Volume	Relationship between level and volume at Node I
VARIABLE 1	COMP	Measurement: Volume Operator: MINUS Condition 1: STORED Condition 2: STOREDI	VARIABLE 1 = Volume at Node D - Volume at Node I
RANGE 5	DMORE	Range type: Variable Location Definition: COMP Minimum: 0.000 Maximum:	TRUE if Volume at Node D is greater than Volume at Node I
RANGE 6	IMORE	Range type: Variable Location Definition: COMP Minimum: Maximum: 0.000	TRUE if Volume at Node I is greater than Volume at Node D
LOGIC 1	UPD	Operator: AND Condition 1: UPFLOW Condition 2: DMORE	TRUE if flow in conduit H.1 is between 0.000 m3/s and 0.580 m3/s AND Volume at Node D is greater than Volume at Node I
LOGIC 2	DOWND	Operator: AND Condition 1: DOWNFLOW Condition 2: IMORE	TRUE if flow in conduit H.1 is greater than 0.580 m3/s AND Volume at Node I is greater than Volume at Node D
LOGIC 3	UPI	Operator: AND Condition 1: UPFLOW Condition 2: IMORE	TRUE if flow in conduit H.1 is between 0.000 m3/s and 0.580 m3/s AND Volume at Node I is greater than Volume at Node D
LOGIC 4	DOWNI	Operator: AND Condition 1: DOWNFLOW Condition 2: DMORE	TRUE if flow in conduit H.1 is greater than 0.580 m3/s AND Volume at Node D is greater than Volume at Node I
CONTROLLER 1	UP	Type: INC Measurement Interval: 300	Measurement interval of orifice increment equals 300 s

Local Dependents

Variable Limiting Discharge Orifice D.2

Component	Name	Parameters	Effect
RULE 1	UPD	Condition: UPD Rule type: CTRL Controller: UP Setpoint type: FIXED 0.010 m3/s	If the flow in conduit H.1 is between 0.000 m3/s and 0.580 m3/s AND Volume at Node D is greater than Volume at Node I, increment the regulator by 0.01 m3/s every 300 s.
RULE 2	DOWND	Condition: DOWND Rule type: CTRL Controlloer: UP Setpoint type: FIXED -0.010m3/s	If the flow in conduit H.1 is greater than 0.580 m3/s AND Volume at Node I is greater than Volume at Node D, decrement the regulator by 0.01 m3/s every 300 s.

 

Variable Limiting Discharge Orifice I.2

Component	Name	Parameters	Effect
RULE 1	UPI	Condition: UPI Rule type: CTRL Controller: UP Setpoint type: FIXED 0.010m3/s	If the flow in conduit H.1 is between 0.000 m3/s and 0.580 m3/s AND Volume at Node I is greater than Volume at Node D, increment the regulator by 0.01 m3/s every 300 s.
RULE 2	DOWNI	Condition: DOWNI Rule type: CTRL Controller: UP Setpoint type: FIXED -0.010m3/s	If the flow in conduit H.1 is greater than 0.580 m3/s AND Volume at Node D is greater than Volume at Node I, decrement the regulator by 0.01 m3/s every 300 s.

 

RTC Scenario Steps

1. Insert Ranges to measure flow in conduit H.1  

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2. Insert Ranges to measure level at Node D and Node I

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3. Define relationship between level and volume at Node D and Node I by inserting Tables

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4. Insert a variable to calculate the difference between volume at Node D and volume at Node I

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5. Insert Ranges to measure volumes at Node D or Node I

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6. Insert Logics to determine whether flow in conduit H.1 is less than or greater than 0.580 m3/s and whether the volume at Node D or Node I is greater

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7. Insert Controller to define time interval for incrementing regulator settings

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8. Insert Regulators to be controlled

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9. Insert Rules for each Regulator to determine how the orifice opening is to be regulated

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