modelSideCold

Control block for cold side
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Information

This block serves as the controller for the cold side of the ETS in Buildings.Obsolete.DHC.ETS.Combined.Controls.Supervisory. It computes the following control signals.

  • Control signals for ambient sources yAmb (array)
    The cold rejection control signal yielded by the hot side controller is processed as follows.
    • A controller is used to track the chilled water supply temperature (CHWST) set point. This controller is enabled when cooling is enabled. It yields a control signal value between 0 and nSouAmb.
    • The systems serving as ambient sources are then controlled in sequence by mapping the minimum between the CHWST control loop output and the part of the cold rejection signal between 0 and nSouAmb to a nSouAmb-array of signals between 0 and 1.
  • Chilled water supply temperature set point TChiWatSupSet
    The remaining part of the cold rejection signal between nSouAmb and nSouAmb+1 is used to reset the CHWST set point between a maximum value provided as an input variable, and a minimum value provided as a parameter.
  • Control signal for the evaporator loop isolation valve yIsoAmb
    The valve is commanded to be fully open whenever the cold rejection control signal is greater than zero. The command signal is held for 5 min to avoid short cycling.

Parameters

TypeNameDefaultDescription
IntegernSouAmb1Number of ambient sources to control
RealTChiWatSupSetMinMinimum value of chilled water supply temperature set point
Buildings.Controls.OBC.CDL.Types.SimpleControllercontrollerTypeBuildings.Controls.OBC.CDL.Types.SimpleController.PIType of controller
Realk0.1Gain of controller
RealTi120Time constant of integrator block

Connectors

TypeNameDefaultDescription
Buildings.Controls.OBC.CDL.Interfaces.BooleanInputuHeaCooEnable signal for heating or cooling
Buildings.Controls.OBC.CDL.Interfaces.RealInputTSetSupply temperature set point (heating or chilled water)
Buildings.Controls.OBC.CDL.Interfaces.RealInputuColCold rejection control signal
Buildings.Controls.OBC.CDL.Interfaces.RealInputTBotTemperature at bottom of tank
Buildings.Controls.OBC.CDL.Interfaces.RealOutputTChiWatSupSetChilled water supply temperature set point
Buildings.Controls.OBC.CDL.Interfaces.RealOutput[nSouAmb]yAmbControl signal for ambient sources
Buildings.Controls.OBC.CDL.Interfaces.RealOutputyValIsoAmbient loop isolation valve control signal

Components

TypeNameDefaultDescription
Buildings.Controls.OBC.CDL.Reals.Line[nSouAmb]mapFunMapping functions for ambient source control
Buildings.Controls.OBC.CDL.Reals.Sources.Constant[nSouAmb]x1x1
Buildings.Controls.OBC.CDL.Routing.RealScalarReplicatorrepReplicate control signal
Buildings.Controls.OBC.CDL.Reals.Sources.Constant[nSouAmb]f1f1
Buildings.Controls.OBC.CDL.Reals.Sources.Constant[nSouAmb]f2f2
Buildings.Controls.OBC.CDL.Reals.Sources.Constant[nSouAmb]x2x2
Buildings.Controls.OBC.Utilities.PIDWithEnableconTChiWatSupController for CHWST
Buildings.Controls.OBC.CDL.Reals.LinemapFunTChiSupSetMapping function for CHWST reset
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantminTChiWatSupMinimum value of chilled water supply temperature
Buildings.Controls.OBC.CDL.Reals.AddParameteraddParOne minus control loop output
Buildings.Controls.OBC.CDL.Reals.MultiplyByParametergaiGain factor
Buildings.Controls.OBC.CDL.Reals.Maxmax1CHWST reset signal
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantzerZero
Buildings.Controls.OBC.CDL.Reals.AddParametersubNumSouControl signal minus nSouAmb
Buildings.Controls.OBC.CDL.Reals.Minmin1Ambient source control signal
Buildings.Controls.OBC.CDL.Reals.LimitSlewRateramLimHeaLimit the rate of change
Buildings.Controls.OBC.CDL.Conversions.BooleanToRealbooToReaConvert DO to AO signal
Buildings.Controls.OBC.CDL.Reals.GreaterThresholdgreThrControl signal is non zero (with 1% tolerance)
Buildings.Controls.OBC.CDL.Logical.TrueFalseHoldtruFalHolHold logical signal to avoid short cycling
Buildings.Controls.OBC.CDL.Logical.PrepreBlock to avoid an algebraic loop during initialization

Revisions

  • March 7, 2025, by Michael Wetter:
    Increased, and added where missing, hysteresis, as the input signal is the output of the PID controller.
  • November 22, 2024, by Michael Wetter:
    Reduced number of time events by replacing zero order hold with true and false hold, and increasing the minimum cycle time.
    This is for #4058.
  • July 31, 2020, by Antoine Gautier:
    First implementation.