blockPlantReset
Information
This logic is used in primary-only and primary-secondary systems serving differential pressure controlled pumps.
CHW loops with differential pressure control
The CHW supply temperature setpoint and pump differential pressure setpoint are reset based on the current value of the logic variable called "CHW Plant Reset" as shown below and described subsequently.
HW loops with differential pressure control
The HW supply temperature setpoint and pump differential pressure setpoint are reset based on the current value of the logic variable called "HW Plant Reset" as shown below and described subsequently.
Generic reset logic applicable to all plants
From 0 % loop output to resDp_max loop output, reset
differential pressure setpoint from dpSet_min to dpSet_max.
From resTSup_min loop output to 100 % loop output, reset supply
temperature setpoint from TSupSetLim to TSup_nominal.
CHW/HW Plant Reset variable is reset using trim and respond logic with the following parameters:
| Variable | Value | Definition |
|---|---|---|
| Device | Any pump distribution loop | Associated device |
| SP0 | res_init | Initial reset value |
| SPmin | res_min | Minimum reset value |
| SPmax | res_max | Maximum reset value |
| Td | dtDel | Delay time before the reset begins |
| T | dtRes | Time step |
| I | nReqResIgn | Number of ignored requests |
| R | nReqRes | Number of requests |
| SPtrim | tri | Trim amount |
| SPres | rsp | Respond amount |
| SPres_max | rsp_max | Maximum response per time interval |
The plant reset loop is enabled when the plant is enabled and disabled when the plant is disabled.
When a plant stage change is initiated, the plant reset logic is disabled and
value fixed at its last value for the longer of dtHol and the time it
takes for the plant to successfully stage.
Plants serving more than one set of differential pressure controlled pumps
A unique instance of the above reset is used for each set of differential pressure controlled pumps.
- Reset requests from all loads served by a set of pumps are directed to those pumps’ reset loop only.
- The differential pressure setpoint output from each reset is used in the ∆p control loop for the associated set of pumps only, i.e., the ∆p setpoint will not change for any other ∆p control loops.
Plants where more than one remote ∆p sensor serves a given set of primary or secondary pumps ∆p
Where more than one remote ∆p sensor serves a given set of primary or secondary pumps,
remote ∆p setpoints for all remote sensors serving those pumps shall increase in unison.
Note: if remote sensors have different dpSet_max values, then the amount
each ∆p setpoint changes per percent loop output will differ.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | nSenDpRem | Number of remote loop differential pressure sensors used for pump speed control | |
| Real[nSenDpRem] | dpSet_max | Maximum differential pressure setpoint | |
| Real | dpSet_min | 5*6894 | Minimum value to which the differential pressure can be reset |
| Real | TSup_nominal | Design supply temperature | |
| Real | TSupSetLim | Limit value to which the supply temperature can be reset | |
| Advanced | |||
| Real | dtHol | 900 | Minimum hold time during stage change |
| Real | resDp_max | 0.5 | Upper limit of plant reset interval for differential pressure reset |
| Real | resTSup_min | resDp_max | Lower limit of plant reset interval for supply temperature reset |
| Advanced › Trim and respond | |||
| Real | res_init | 1 | Initial reset value |
| Real | res_min | 0 | Minimum reset value |
| Real | res_max | 1 | Maximum reset value |
| Real | dtDel | 900 | Delay time before the reset begins |
| Real | dtRes | 300 | Time step |
| Integer | nReqResIgn | 2 | Number of ignored requests |
| Real | tri | -0.02 | Trim amount |
| Real | rsp | 0.03 | Respond amount (must have opposite sign of trim amount) |
| Real | rsp_max | 0.07 | Maximum response per time interval (must have same sign as respond amount) |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Interfaces.IntegerInput | nReqRes | Sum of reset requests of all loads served | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput | u1Ena | Plant enable | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput | u1StaPro | Staging process in progress | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | TSupSet | Supply temperature setpoint | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput[nSenDpRem] | dpSet | Differential pressure setpoint |
Components
Revisions
-
June 7, 2024, by Antoine Gautier:
Updated hold logic during staging after refactoring trim and respond block.
This is for #3761. -
March 29, 2024, by Antoine Gautier:
First implementation.