[SplyChw22] Supply chain chilled water, data exchange with other plants, with valve position evaluation

Program block, name / node subtype: [SplyChw22] Supply chain chilled water, data exchange with other plants, with valve position evaluation

Library hierarchy: Coordination

Family: SplyChw

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Diagram

Configurator

info

Program blocks are stored in the library without I/Os. Use the auto-create and auto-connect functions to create I/Os and/or to connect them to the interface blocks, e.g., R_A, CMD_B. Alternatively, take the I/Os from the folder containing the predefined I/Os in the library and/or from the plant and connect them to the interface blocks.

Function

SplyChw22 connects one or more chilled water consumers, e.g., air handlers, to the cooling plant.

The most important functions in the program block are:

  • Cooling demand collection and evaluation
  • Chilled water temperature setpoint calculation and its correction based on valve position evaluation of the consumers.
Mandatory elements

Name

Description

Type

Alarm / Notification class

Trend / Type

SpCReq

Setpoint for cooling request

ACalcVal: Analog calculated value

N/A

N/A

CReq

Cooling request

BCalcVal: Binary calculated value

N/A

N/A

Optional elements

Name

Description

Type

Alarm / Notification class

Trend / Type

SpCReqMax

Maximum setpoint cooling request

ACnfVal: Analog configuration value

N/A

N/A

Dmd(1)

Demand (1)

Chart

N/A

N/A

Dmd(2)

Demand (2)

Chart

N/A

N/A

Dmd(3)

Demand (3)

Chart

N/A

N/A

Dmd(4)

Demand (4)

Chart

N/A

N/A

Dmd(5)

Demand (5)

Chart

N/A

N/A

Dmd(6)

Demand (6)

Chart

N/A

N/A

Dmd(7)

Demand (7)

Chart

N/A

N/A

Dmd(8)

Demand (8)

Chart

N/A

N/A

Further options

Description

Setpoint correction for flow temperature based on valve position evaluation

Elements that belong to this option:

Setpoint correction for lower flow temperature | ACnfVal: Analog configuration value

Setpoint correction for higher flow temperature | ACnfVal: Analog configuration value

Flow temperature setpoint for cooling | ACnfVal: Analog configuration value

Further information

Cooling demand collection and evaluation

SplyChw22 receives binary chilled water demand signals [ChwDmd1...n] from consumers, and calculates a binary value for the cooling request output pin [CReq]. If at least one chilled water demand signal is True, [CReq] is True.

Chilled water temperature setpoint calculation and its correction based on valve position evaluation of the consumers

SplyChw22 receives valve position values from consumers [VlvPosVal1...n], and calculates a representative valve position value [ChwVlvPosEvl]. [ChwVlvPosEvl] is the average of valve positions that:

  • Are ≥ 10 %
  • Have no disturbances
  • Are from consumers with an active chilled water demand signal

A linear function (configurable) uses [ChwVlvPosEvl] to calculate a chilled water supply temperature setpoint correction value between SpCorrTFlHi and SpCorrTFlLo:

Key

SpCorrTFlHi

Setpoint correction for higher flow temperature

SpCorrTFlLo

Setpoint correction for lower flow temperature

ChwVlvPosEvl

Supply chain chilled water valve position evaluation

The calculated setpoint correction value is added to the base setpoint SpTFl. The result is the chilled water cooling request setpoint value [SpCReq] (chart output pin). To prevent abnormally low setpoints, a 3°C lower limit is hard-coded in the chart.

The suggested setpoint value [SpCReq] can be delivered to the cooling plant or other coordinator(s) (SplyChw23).