modelHeadControl

Information

This example validates Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Staging.Processes.Subsequences.HeadControl. It has four instances as below to demonstrate the process of chiller head pressure control when the plant is in the staging process.

The instance enaHeaCon shows the head pressure control when the plant is in the staging up process, and it will enable chiller 2 (nexChaChi=2).

• Before 18 seconds, the plant is not in the staging process, uStaPro=false. There is no change in the chiller head pressure control.
• At 24 seconds, the condenser water pump speed (or number) has been changed (uUpsDevSta=true). However, it is still not the time to change the chiller head pressure control.
• After the threshold time (thrTimEna=10 seconds) at 34 seconds, it enables the head pressure control of the enabling chiller 2.
• After the waiting time (waiTim=30 seconds) at 64 seconds, the head pressure control process is done (yEnaHeaCon=true).

The instance disHeaCon shows the head pressure control when the plant is in the staging up process and it requires enabling a large chiller and disabling a small chiller. In this case, it disables chiller 2 (nexChaChi=2).

• Before 18 seconds, the plant is not in the staging process, uStaPro=false. There is no change in the chiller head pressure control.
• At 24 seconds, the chiller 2 becomes not requesting for condenser water flow (uUpsDevSta=true). It disables the head pressure control of chiller 2 and the head pressure control process is done (yEnaHeaCon=true).

The instance disHeaCon1 shows the head pressure control when the plant is in the staging down process and it requires disabling chiller 2 (nexChaChi=2).

• Before 18 seconds, the plant is not in the staging process, uStaPro=false. There is no change in the chiller head pressure control.
• At 24 seconds, the chiller 2 becomes not requesting for condenser water flow (uUpsDevSta=true). It disables the head pressure control of chiller 2 and the head pressure control process is done (yEnaHeaCon=true).

The instance enaHeaCon1 shows the head pressure control when the plant is in the staging down process, and it requires disabling a large chiller and enabling a small chiller. In this case, it enables chiller 2 (nexChaChi=2).

• Before 18 seconds, the plant is not in the staging process, uStaPro=false. There is no change in the chiller head pressure control.
• At 24 seconds, the minimum flow bypass valve has changed the position (uUpsDevSta=true). It enables the head pressure control of the enabling chiller 2.
• After the waiting time (waiTim=30 seconds) at 54 seconds, the head pressure control process is done (yEnaHeaCon=true).

Components

Revisions

• September 24, 2019, by Jianjun Hu:
  First implementation.