blockController
Controller for chilled water minimum flow bypass valve
Information
Block that controls chilled water minimum flow for primary-only plants with a minimum flow bypass valve, according to ASHRAE Guideline 36-2021, section 5.20.8 Chilled water minimum flow bypass valve.
The minimum chilled water flow setpoint VChiWatSet_flow is specified by
the block
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.MinimumFlowBypass.FlowSetpoint.
When any chilled water pump is proven on (uChiWatPum = true),
the bypass valve PID loop shall be enabled. Otherwise, the valve shall be opened 100%.
When enabled, the bypass valve loop shall be biased to start with the valve
100% open.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | nChi | 2 | Total number of chillers |
| Real[nChi] | minFloSet | Minimum chilled water flow through each chiller | |
| 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 | Time constant of derivative block |
| Real | yMax | 1 | Upper limit of output |
| Real | yMin | 0.1 | Lower limit of output |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput | uChiWatPum | Maximum status feedback of all the chilled water pumps: true means at least one pump is proven on | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | VChiWat_flow | Measured chilled water flow rate through chillers | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | VChiWatSet_flow | Chiller water minimum flow setpoint | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | yValPos | Chilled water minimum flow bypass valve position |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.Utilities.PIDWithEnable | valPos | Bypass valve position PI controller |
Revisions
-
January 31, 2019, by Jianjun Hu:
First implementation.