modelChilledWaterBypass
Controller for chilled water bypass valve
Information
This model implements the chilled water loop bypass valve control logic as follows:
When the plant is on, the PID controller controls the valve opening ratio to reach the scaled mass flow rate setpoint.
The setpoint is mMin_flow multiplied by the number of chillers
that are on. mMin_flow is the minimum mass flow rate required by
one chiller.
This control sequence assumes that all the chillers are identical and the cooling load is evenly split between all of the chillers that are on.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | numChi | Number of chillers | |
| Real | mMin_flow | Minimum mass flow rate of single chiller | |
| Buildings.Controls.OBC.CDL.Types.SimpleController | controllerType | Buildings.Controls.OBC.CDL.Types.SimpleController.PI | Type of controller |
| Real | k | 0.06 | Gain of controller |
| Real | Ti | 60 | Time constant of Integrator block |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput[numChi] | chiOn | On signals of the chillers | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | mFloChi | Mass flow rate through the chillers | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | y | Bypass valve opening ratio |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Reals.PIDWithReset | bypValCon | Chilled water bypass valve controller | |
| Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger[numChi] | booToInt | Boolean signal to integer | |
| Buildings.Controls.OBC.CDL.Integers.GreaterThreshold | intGreThr | Greater than zero | |
| Buildings.Controls.OBC.CDL.Integers.MultiSum | numChiOn | Number of chillers on | |
| Buildings.Controls.OBC.CDL.Conversions.IntegerToReal | intToRea | Integer to real | |
| Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter | mFloSetSca | Normalize mass flowrate setpoint | |
| Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter | mFloBypSca | Normalize the measured mass flowrate |
Revisions
-
January 27, 2023, by Michael Wetter:
Removed connection to itself. -
December 14, 2022, by Kathryn Hinkelman:
Corrected measured mass flow rate to be on the chiller leg in order to control minimum flow rate through the chillers.
This is for #2912. -
May 3, 2021 by Jing Wang:
First implementation.