Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.HeadPressure.Subsequences.Validation

Collection of validation models

Information

This package contains validation models for the classes in Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.HeadPressure.Subsequences.

Note that most validation models contain simple input data which may not be realistic, but for which the correct output can be obtained through an analytic solution. The examples plot various outputs, which have been verified against these solutions. These model outputs are stored as reference data and used for continuous validation whenever models in the library change.

Package Content

Name	Description
ControlLoop	Validate sequence of output head pressure control signal
MappingWithWSE	Validate sequence of specifying equipment setpoint based on head pressure control loop output
MappingWithoutWSE	Validate sequence of specifying equipment setpoint based on head pressure control loop output

Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.HeadPressure.Subsequences.Validation.ControlLoop

Validate sequence of output head pressure control signal

Information

This example validates Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.HeadPressure.Subsequences.ControlLoop. It demonstrates how the head pressure control loop signal is generated.

• Before 0.5 seconds, the head pressure control loop is not enabled (uHeaPreEna=false). The loop output is not valid and will not be used.
• At 0.5 seconds, the head pressure control loop is enabled. The PID controller resets the output from 0.
• From 0.5 seconds to 2.5 seconds, the difference between the condenser water return temperature and the chilled water supply temperature is 2 °K and it is less than the minimum LIFT (10 °K). The reverse acting PID controller gradually increases the output to 1.
• From 2.5 seconds to 4 seconds, the difference between the condenser water return temperature and the chilled water supply temperature is 13 °K and it is greater than the minimum LIFT (10 °K). The reverse acting PID controller gradually decreases the output to 0.
• After 4 seconds, the head pressure control loop becomes disabled (uHeaPreEna=false). The loop output is not valid and will not be used.

Modelica definition

Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.HeadPressure.Subsequences.Validation.MappingWithWSE

Validate sequence of specifying equipment setpoint based on head pressure control loop output

Information

This example validates Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.HeadPressure.Subsequences.MappingWithWSE. It demonstrates the setpoints control based on the output from the head pressure control loop.

The instances witWSE and noWSE show the control when the waterside economizer is enabled and disabled respectively.

• In instance withWSE, the economizer is enabled. Thus, the maximum tower speed setpoint and the condenser water pump speed setpoint are equal their maximum, which is 1. The head pressure control valve position yHeaPreConVal resets from 100% open at 0% loop output to minimum position minHeaPreValPos (0.1) at 100% loop output.
• In instance noWSE, the economizer is disabled.
  • When the loop signal uHeaPreCon changes from 0 to 50%, the maximum cooling tower speed setpoint yMaxTowSpeSet resets from 100% to the minimum speed minTowSpe (0.1).
  • When the loop signal uHeaPreCon changes from 50% to 100%, the water pump speed setpoint yConWatPumSpeSet resets from the stage desConWatPumSpe (0.75) to the minimum speed minConWatPumSpe (0.1).
  • The head pressure control valve is fully open.
• For both instances, when the head pressure control loop becomes disabled, the head pressure control valve is fully closed; the maximum tower speed setpoint and the condenser water pump speed setpoints become 0.

Modelica definition

Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.HeadPressure.Subsequences.Validation.MappingWithoutWSE

Validate sequence of specifying equipment setpoint based on head pressure control loop output

Information

This example validates Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.HeadPressure.Subsequences.MappingWithoutWSE. It demonstrates the setpoints control based on the output from the head pressure control loop.

The instances fixPumSpe and varPumSpe show the control of the plants with the fixed speed condenser water pump and the variable speed condenser water pump, respectively.

• In instance fixPumSpe, the condenser water pump speed is fixed.
  • When the loop signal uHeaPreCon changes from 0 to 50%, the maximum cooling tower speed setpoint yMaxTowSpeSet resets from 100% to the minimum speed minTowSpe (0.1).
  • When the loop signal uHeaPreCon changes from 50% to 100%, the head pressure control valve setpoint yHeaPreConVal resets from 100% to the minimum position minHeaPreValPos (0.1).
• In instance varPumSpe, the condenser water pump speed is variable.
  • When the loop signal uHeaPreCon changes from 0 to 50%, the maximum cooling tower speed setpoint yMaxTowSpeSet resets from 100% to the minimum speed minTowSpe (0.1).
  • When the loop signal uHeaPreCon changes from 50% to 100%, the condenser water pump speed setpoint yConWatPumSpeSet resets from the design condenser water pump speed desConWatPumSpe to the minimum speed minConWatPumSpe (0.1).
• For both instances, when the head pressure control loop becomes disabled, the head pressure control valve is fully closed; the maximum tower speed setpoint and the condenser water pump speed setpoints become 0.

Modelica definition