blockController
Plant controller
Extends from BaseClasses.PartialController (Interface class for plant controller).
Information
This block implements the following control functions.
- Plant heating and cooling staging and HRC operating mode selection, see description in Buildings.DHC.Plants.Combined.Controls.BaseClasses.StagingPlant.
- CW loop operating mode selection, see description in Buildings.DHC.Plants.Combined.Controls.BaseClasses.ModeCondenserLoop.
- TES tank cycle flag selection, see description in Buildings.DHC.Plants.Combined.Controls.BaseClasses.TankCycle.
- Load balancing, temperature and flow setpoint tracking for chillers and HRCs depending on active operating modes, see description in Buildings.DHC.Plants.Combined.Controls.BaseClasses.ValveCondenserEvaporator.
- Cooling tower pumps and cooling tower fans control, see description in Buildings.DHC.Plants.Combined.Controls.BaseClasses.CoolingTowerLoop.
- Air-to-water heat pump control, see below.
- CHW, HW, CWE and CWC pumps, see below.
Heat pumps
Heat pumps are enabled whenever Charge Assist mode is active and any CWC pump is enabled. Heat pumps are disabled otherwise.
The supply temperature setpoint is 3 K plus the highest setpoint of the active tank cycle. Note that no limitation of the setpoint value per HP manufacturer specification is taken into account.
CHW, HW, CWE and CWC pumps
The lead pump is enabled based on the logic described in Buildings.DHC.Plants.Combined.Controls.BaseClasses.ValveCondenserEvaporator.
Pumps are staged based on the logic described in Buildings.DHC.Plants.Combined.Controls.BaseClasses.StagingPump.
When any pump is enabled, the pump speed is modulated by a PI controller tracking a differential pressure setpoint at the boundaries of the circuit served by the pump. The control loop is biased to launch from 100 % (maximum speed). All pumps within the same group receive the same speed command signal.
The differential pressure setpoint for the CHW and HW loops is provided as a control input. Ideally, a reset logic based on consumer valve requests should be implemented to adapt those setpoints to the demand. For the sake of simplicity, the differential pressure setpoint for the CWC and CWE loops is a fixed parameter (design pressure drop).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | PLRStaTra (from PartialController) | 0.85 | Part load ratio triggering stage transition |
| Real | QChiWat_flow_nominal (from PartialController) | QChiWatChi_flow_nominal + QChiWatCasCoo_flow_nominal | Plant cooling design heat flow rate (all units) |
| Real | cp_default (from PartialController) | Buildings.Utilities.Psychrometrics.Constants.cpWatLiq | Specific heat capacity of the fluid |
| CHW loop and cooling-only chillers | |||
| Integer | nChi (from PartialController) | Number of units operating at design conditions | |
| Integer | nPumChiWat (from PartialController) | Number of CHW pumps operating at design conditions | |
| Real | TChiWatSup_nominal (from PartialController) | Design (minimum) CHW supply temperature | |
| Real | QChiWatChi_flow_nominal (from PartialController) | Cooling design heat flow rate of cooling-only chillers (all units) | |
| Real | mChiWat_flow_nominal (from PartialController) | CHW design mass flow rate (all units) | |
| Real | dpChiWatSet_max (from PartialController) | Design (maximum) CHW differential pressure setpoint | |
| Real | mChiWatChi_flow_nominal (from PartialController) | Chiller CHW design mass flow rate (each unit) | |
| Real | mChiWatChi_flow_min (from PartialController) | Chiller CHW minimum mass flow rate (each unit) | |
| Real | mConWatChi_flow_nominal (from PartialController) | Chiller CW design mass flow rate (each unit) | |
| Real | dpEvaChi_nominal (from PartialController) | Chiller evaporator design pressure drop (each unit) | |
| Real | dpValEvaChi_nominal (from PartialController) | Chiller evaporator isolation valve design pressure drop (each unit) | |
| Real | dTLifChi_min (from PartialController) | Minimum chiller lift at minimum load | |
| Real | dTLifChi_nominal (from PartialController) | Design chiller lift | |
| HW loop and heat recovery chillers | |||
| Integer | nChiHea (from PartialController) | Number of units operating at design conditions | |
| Integer | nPumHeaWat (from PartialController) | Number of HW pumps operating at design conditions | |
| Real | THeaWatSup_nominal (from PartialController) | Design (maximum) HW supply temperature | |
| Real | QChiWatCasCoo_flow_nominal (from PartialController) | Cooling design heat flow rate of HRC in cascading cooling mode (all units) | |
| Real | QChiWatCasCoo_flow_nominal_approx (from PartialController) | Cooling design heat flow rate of HRC in cascading cooling mode (all units), approximate for scaling | |
| Real | QHeaWat_flow_nominal (from PartialController) | Heating design heat flow rate (all units) | |
| Real | mHeaWat_flow_nominal (from PartialController) | HW design mass flow rate (all units) | |
| Real | dpHeaWatSet_max (from PartialController) | Design (maximum) HW differential pressure setpoint | |
| Real | mChiWatChiHea_flow_nominal (from PartialController) | HRC CHW design mass flow rate (each unit) | |
| Real | mChiWatChiHea_flow_min (from PartialController) | HRC CHW minimum mass flow rate (each unit) | |
| Real | mConWatChiHea_flow_nominal (from PartialController) | HRC CW design mass flow rate (each unit) | |
| Real | mHeaWatChiHea_flow_min (from PartialController) | Chiller HW minimum mass flow rate (each unit) | |
| Real | dpEvaChiHea_nominal (from PartialController) | Design chiller evaporator pressure drop (each unit) | |
| Real | dpValEvaChiHea_nominal (from PartialController) | HRC evaporator isolation valve design pressure drop (each unit) | |
| CW loop, TES tank and heat pumps | |||
| Integer | nHeaPum (from PartialController) | Number of heat pumps operating at design conditions | |
| Integer | nPumConWatCon (from PartialController) | Number of CW pumps serving condenser barrels at design conditions | |
| Integer | nPumConWatEva (from PartialController) | Number of CW pumps serving evaporator barrels at design conditions | |
| Real | QHeaPum_flow_nominal (from PartialController) | Heating design heat flow rate of heat pumps (all units) | |
| Real | mConWatCon_flow_nominal (from PartialController) | Design total CW mass flow rate through condenser barrels (all units) | |
| Real | mConWatEva_flow_nominal (from PartialController) | Design total CW mass flow rate through evaporator barrels (all units) | |
| Real | dpConWatConSet_max (from PartialController) | Design (maximum) CW condenser loop differential pressure setpoint | |
| Real | dpConWatEvaSet_max (from PartialController) | Design (maximum) CW evaporator loop differential pressure setpoint | |
| Real[2,2] | TTanSet (from PartialController) | Tank temperature setpoints: 2 cycles with 2 setpoints | |
| Real | fraUslTan (from PartialController) | Useless fraction of TES | |
| Integer | nTTan (from PartialController) | 0 | Number of tank temperature points |
| Real[5] | ratFraChaTanLim (from PartialController) | {-0.3, -0.2, -0.15, -0.10, -0.08} | Rate of change of tank charge fraction (over 10, 30, 120, 240, and 360') that triggers Charge Assist (<0) |
| Cooling tower loop | |||
| Integer | nCoo (from PartialController) | Number of cooling tower cells operating at design conditions | |
| Integer | nPumConWatCoo (from PartialController) | Number of CW pumps serving cooling towers at design conditions | |
| Real | dTHexCoo_nominal (from PartialController) | Design heat exchanger approach | |
| Dynamics › Motor speed | |||
| Real | riseTime (from PartialController) | 30 | Time needed to change motor speed between zero and full speed |
| Dynamics › Time needed to open or close valve | |||
| Real | strokeTime (from PartialController) | 120 | Valve stroke time |
Connectors
Components
Revisions
-
February 24, 2023, by Antoine Gautier:
First implementation.