modelController

Validation head pressure controller
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Information

This example validates composed chiller plant controller Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Controller. It shows the process of enabling plant, enabling waterside economizer and staging up one chiller. The plant:

  • is less coupled;
  • has waterside economizer and the chilled water flow through the economizer is controlled using heat exchanger pump;
  • has 2 parallel identical chillers and do not have head pressure control signal;
  • has 2 headed chilled water pumps, 1 remote differential pressure sensor and do not have local differential pressure sensor hardwired to the plant controller;
  • has 2 headed variable speed condenser water pumps;
  • has cooling tower with 2 cells.

The example shows following process:

  • At 15 minutes, the plant becomes enabled in waterside economizer mode. The economizer is enabled and the heat exchanger pump starts operating (wseSta.yPumSpe is greater than 0). The condenser water pump becomes enabled and the number (1) of enabling pumps is specified by the parameter desConWatPumNum and it starts operating at speed (0.5) specified by (desConWatPumSpe). The cooling tower cell 1 becomes enabled and its isolation valve starts open. After 5 minutes (chaTowCelIsoTim) at 20 minutes when the isolation valve is fully open, it turns on the cell 1.
  • At 115 minutes, the plant starts staging up (staSetCon.yUp=true, upProCon.yStaPro=true) and it stages up chiller 1.
  • In the staging up process, at 127.07 minutes, it increases the condenser water pump speed (0.6) and increases number (2) of the pump. Also, it starts staging up cooling tower (upProCon.yTowStaUp=true) at the same moment. At 127.241 minutes, it enables the chiller 1 head pressure control. When the chilled water isolation valve is fully open at 132.741 minutes, it then turns on chiller 1. The staging up process is done (upProCon.yStaPro=false).

Components

TypeNameDefaultDescription
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.ControllerchiPlaConChiller plant controller
Buildings.Controls.OBC.CDL.Reals.Sources.TimeTabletimTabLin1Time table with smoothness method of constant segments
Buildings.Controls.OBC.CDL.Conversions.RealToIntegerreaToInt1Convert real to integer
Buildings.Controls.OBC.CDL.Reals.Sources.RampTChiWatSupChilled water supply
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantphiOutdoor relative humidity
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantTOut1Outdoor dry bulb temperature
Buildings.Controls.OBC.CDL.Reals.Sources.RampTChiWatRetUpChilled water return temperature, upstream of WSE
Buildings.Controls.OBC.CDL.Reals.Sources.RampTChiWatRetDowChilled water return downstream of WSE
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantTConWatRetCondenser water return temperature
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantTConWatSupCondenser water supply temperature
Buildings.Controls.OBC.CDL.Reals.Sources.RampdpChiWatChilled water differential pressure
Buildings.Controls.OBC.CDL.Reals.Sources.RampwatLevWater level in cooling tower
Buildings.Controls.OBC.CDL.Integers.GreaterThresholdintGreThrCheck if the WSE pump should be enabled
Buildings.Controls.OBC.CDL.Reals.Sources.RampTEntHexChilled water temperature entering heat exchanger
Buildings.Controls.OBC.CDL.Reals.Sources.TimeTablechiWatFloTime table with smoothness method of constant segments
Buildings.Controls.OBC.CDL.Logical.PrechiOneChiller one status
Buildings.Controls.OBC.CDL.Logical.PrechiTwoChiller two status
Buildings.Controls.OBC.CDL.Logical.Pre[2]conWatPumCondenser water pump status setpoint
Buildings.Controls.OBC.CDL.Logical.Pre[2]towStaTower cell status
Buildings.Controls.OBC.CDL.Logical.Sources.ConstantplaEnaPlant enable
Buildings.Controls.OBC.CDL.Reals.Sources.RampTChiWatRetDow1Chilled water return downstream of WSE
Buildings.Controls.OBC.CDL.Logical.Pre[2]chiWatPumChilled water pumps
Buildings.Controls.OBC.CDL.Discrete.ZeroOrderHold[2]zerOrdHol7Output the input signal with a zero order hold
Buildings.Controls.OBC.CDL.Reals.MultiplyByParametergaiTimes the nominal flow rate
Buildings.Controls.OBC.CDL.Reals.Sources.RampTChiWatEntChiChilled water return, entering chiller

Revisions

  • September, 2021, by Jianjun Hu:
    Refactored the implementations.
  • August 30, 2020, by Milica Grahovac:
    First implementation.