blockSupplySignals

Multizone VAV AHU supply air temperature control loop and coil valves position

Information

Block that outputs the supply temperature control loop signal, and the coil valve postions for VAV system with multiple zones, implemented according to Section 5.16.2.3 of the ASHRAE Guideline G36, May 2020.

The supply air temperature control loop signal uTSup is computed using a PI controller that tracks the supply air temperature setpoint TSupSet. If the fan is off, then uTSup = 0.

Heating valve control signal (or modulating electric heating coil if applicable) yHeaCoi and cooling valve control signal yCooCoi are sequenced based on the supply air temperature control loop signal uTSup. From uTSup = uHea_max to uTSup = -1, yHeaCoi increases linearly from 0 to 1. Similarly, uTSup = uCoo_min to uTSup = +1, yCooCoi increases linearly from 0 to 1.

Image of supply temperature loop

The output uTSup can be used in a controller for the economizer.

Parameters

TypeNameDefaultDescription
Booleanhave_heaCoitrueTrue: the AHU has heating coil. It could be the hot water coil, or the electric heating coil
Booleanhave_cooCoitrueTrue: the AHU has cooling coil. It could be the chilled water coil, or the direct expansion coil
Buildings.Controls.OBC.CDL.Types.SimpleControllercontrollerTypeBuildings.Controls.OBC.CDL.Types.SimpleController.PIType of controller for supply air temperature signal
RealkTSup0.05Gain of controller for supply air temperature signal
RealTiTSup600Time constant of integrator block for supply temperature control signal
RealTdTSup0.1Time constant of derivative block for supply temperature control signal
RealuHea_max-0.25Upper limit of controller signal when heating coil is off. Require -1 < uHea_max < uCoo_min < 1.
RealuCoo_min0.25Lower limit of controller signal when cooling coil is off. Require -1 < uHea_max < uCoo_min < 1.

Connectors

TypeNameDefaultDescription
Buildings.Controls.OBC.CDL.Interfaces.RealInputTAirSupMeasured supply air temperature
Buildings.Controls.OBC.CDL.Interfaces.RealInputTAirSupSetSupply air temperature setpoint
Buildings.Controls.OBC.CDL.Interfaces.BooleanInputu1SupFanSupply fan status
Buildings.Controls.OBC.CDL.Interfaces.RealOutputyHeaCoiHeating coil commanded position
Buildings.Controls.OBC.CDL.Interfaces.RealOutputyCooCoiCooling coil commanded position
Buildings.Controls.OBC.CDL.Interfaces.RealOutputuTSupSupply temperature control signal

Components

TypeNameDefaultDescription
Buildings.Controls.OBC.CDL.Reals.PIDWithResetconTSupController for supply air temperature control signal (to be used by heating coil, cooling coil and economizer)

Revisions

  • August 1, 2020, by Jianjun Hu:
    Updated according to ASHRAE G36 official release.
  • November 1, 2017, by Jianjun Hu:
    First implementation.