blockControlLoop
Sequence to generate head pressure control signal if it is not available from the chiller controller
Information
Block that generates chiller head pressure control loop signal when the signal is not available from chiller controller, according to ASHRAE Guideline 36-2021, section 5.20.10 head pressure control, part 5.20.10.1, and 5.20.10.2.
1. When the head pressure control loop is enabled, a reverse acting PID loop shall
maintain the temperature differential between the chiller condenser water
return (condenser leaving) temperature TConWatRet and chilled water supply temperature
TChiWatSup at the minimum allowable lift minChiLif (chiller lift
equals to TConWatRet minus TChiWatSup)
2. Each operating chiller shall have its own head pressure control loop.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | minChiLif | 10 | Minimum allowable lift at minimum load for chiller |
| PID controller | |||
| Buildings.Controls.OBC.CDL.Types.SimpleController | controllerType | Buildings.Controls.OBC.CDL.Types.SimpleController.PI | Type of controller |
| Real | k | 1 | Gain of controller |
| Real | Ti | 0.5 | Time constant of integrator block |
| Real | Td | 0.5 | Time constant of derivative block |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput | uHeaPreEna | Status of head pressure control: true = ON, false = OFF | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | TConWatRet | Measured condenser water return temperature (condenser leaving) | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | TChiWatSup | Measured chilled water supply temperature | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | yHeaPreCon | Chiller head pressure control loop output |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.Utilities.PIDWithEnable | conPID | Generate head pressure control signal |
Revisions
-
January 30, 2019, by Jianjun Hu:
First implementation.