blockController
Sequence of staging cooling tower cells
Information
Block controls cooling tower fan staging. This is implemented according to ASHRAE Guideline 36-2021, section 5.20.12.1, which specifies tower fan staging process. It includes two subsequences:
- Sequence of identifying total number of enabled cells. See Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.Staging.Subsequences.CellsNumber for a description.
- Sequence of identifying cells that should change status. See Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.Staging.Subsequences.ChangeCells for a description.
- Sequence of process for enabling cells. See Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.Staging.Subsequences.StageProcesses for a description.
Note that in this implementation, input uTowStaCha
is from chiller staging process sequence. The input is also used for the
condenser water pump staging. Thus, the tower stage changes are initiated concurrently
with condenser water pump stage.
The sequence also assumes the cells are enabled in order as it is labelled, meaning that it enabled the cells as cell 1, 2, 3, etc.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | have_WSE | true | Flag to indicate if the plant has waterside economizer |
| Integer | nTowCel | 4 | Total number of cooling tower cells |
| Integer | nConWatPum | 2 | Total number of condenser water pumps |
| Integer | nPlaSta | 6 | Total number of plant stages, including stage zero and the stages with a WSE, if applicable |
| Real[nPlaSta] | staVec | {0, 0.5, 1, 1.5, 2, 2.5} | Plant stage vector with size of total number of stages, element value like x.5 means chiller stage x plus WSE |
| Integer[nPlaSta] | towCelOnSet | {0, 2, 2, 4, 4, 4} | Design number of tower fan cells that should be enabled, according to current chiller stage and WSE status |
| Isolation valves | |||
| Boolean | have_inlIsoVal | true | True: tower cells have the inlet isolation valve |
| Boolean | have_outIsoVal | false | True: tower cells have the outlet isolation valve |
| Boolean | have_endSwi | false | True: tower cells isolatiove valve have the end switch feedback |
| Real | chaTowCelIsoTim | 90 | Nominal time needed for open isolation valve of the tower cells |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Interfaces.IntegerInput | uChiSta | Current chiller stage | |
| Buildings.Controls.OBC.CDL.Interfaces.IntegerInput | uChiStaSet | Current chiller stage setpoint | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput | uTowStaCha | Cooling tower stage change command from plant staging process | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput | uWse | Water side economizer status: true = ON, false = OFF | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput | uEnaPla | True: plant is just enabled | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput | uPla | Plant enabling status | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput | uAnyConWatPum | True: there is condenser water pump on | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput[nTowCel] | u1InlIsoValOpe | Tower cells inlet isolation valve open end switch. True: the isolation valve is fully open | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput[nTowCel] | u1OutIsoValOpe | Tower cells outlet isolation valve open end switch. True: the isolation valve is fully open | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput[nTowCel] | u1InlIsoValClo | Tower cells inlet isolation valve close end switch. True: the isolation valve is fully closed | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput[nTowCel] | u1OutIsoValClo | Tower cells outlet isolation valve close end switch. True: the isolation valve is fully closed | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput[nTowCel] | uTowSta | Vector of tower cells proven on status: true=proven on | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput | yLeaCel | Lead tower cell status | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput[nTowCel] | y1IsoVal | Vector of tower cells isolation valve position | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput[nTowCel] | yTowSta | Vector of tower cells status setpoint | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput | yEndSta | Rising edge to indicate the staging process is done |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.Staging.Subsequences.CellsNumber | enaCel | Total number of enabled cells | |
| Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.Staging.Subsequences.StageProcesses | staPro | Tower staging process | |
| Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.Staging.Subsequences.ChangeCells | ideChaCel | Identify which cell should change status |
Revisions
-
September 14, 2019, by Jianjun Hu:
First implementation.