Plant Component Setpoint Operation Scheme

[kbenne]

The component setpoint operation scheme is not working for components after the supply side mixer, and directly upstream of the supply outlet node. The workaround is to insert a pipe between the setpoint component and the supply outlet node.

This does not work.

This is the workaround.

[jmarrec]

here's where it happens, inside _isSetpointComponent there's a check on line 145

https://github.com/NREL/OpenStudio/blob/7cec475621233fcd772de2c6715ef9252bcbb7a6/src/energyplus/ForwardTranslator/ForwardTranslatePlantEquipmentOperationSchemes.cpp#L136-L153

[jmarrec]

It begs the question of whether you actually need TWO plant eq operation schemes for the same object... In your above example, if I put only one parallel branch (WH1) and one after the spliiter (WH2), you will end up with the waterheaters being referenced by both a HeatingLoad and a ComponentSetpoint one:

PlantEquipmentOperationSchemes,
  Plant Loop 1 Operation Schemes,         !- Name
  PlantEquipmentOperation:HeatingLoad,    !- Control Scheme Object Type 1
  Plant Loop 1 Heating Operation Scheme,  !- Control Scheme Name 1
  Always On Discrete,                     !- Control Scheme Schedule Name 1
  PlantEquipmentOperation:ComponentSetpoint, !- Control Scheme Object Type 2
  Plant Loop 1 Setpoint Operation Scheme, !- Control Scheme Name 2
  Always On Discrete;                     !- Control Scheme Schedule Name 2

PlantEquipmentOperation:HeatingLoad,
  Plant Loop 1 Heating Operation Scheme,  !- Name
  0,                                      !- Load Range Lower Limit 1 {W}
  1000000000,                             !- Load Range Upper Limit 1 {W}
  Plant Loop 1 Heating Equipment List;    !- Range Equipment List Name 1

PlantEquipmentList,
  Plant Loop 1 Heating Equipment List,    !- Name
  WaterHeater:Mixed,                      !- Equipment Object Type 1
  Water Heater Mixed 1,                   !- Equipment Name 1
  WaterHeater:Mixed,                      !- Equipment Object Type 2
  Water Heater Mixed 2;                   !- Equipment Name 2

PlantEquipmentOperation:ComponentSetpoint,
  Plant Loop 1 Setpoint Operation Scheme, !- Name
  WaterHeater:Mixed,                      !- Equipment Object Type 1
  Water Heater Mixed 1,                   !- Equipment Name 1
  Node 3,                                 !- Demand Calculation Node Name 1
  Node 7,                                 !- Setpoint Node Name 1
  Autosize,                               !- Component Flow Rate 1 {m3/s}
  Heating;                                !- Operation Type 1
  [ Note: apparently "missing" the Water Heater Mixed 2 here ]

I haven't found a single E+ example file where a PlantEquipmentOperation:ComponentSetpoint AND another (like PlantEquipmentOperation:Heating/CoolingLoad) are listed on the PlantEquipmentOperationSchemes

@kbenne thoughts please?

[jmarrec]

Ruby test code

include OpenStudio::Model

m = Model.new

p = PlantLoop.new(m)
wh1 = WaterHeaterMixed.new(m)
p.addSupplyBranchForComponent(wh1)

pump = PumpVariableSpeed.new(m)
pump.addToNode(p.supplyInletNode)

sch = ScheduleConstant.new(m)
sch.setValue(45.0)
spm_sch = SetpointManagerScheduled.new(m, sch)
spm_sch.addToNode(wh1.supplyOutletModelObject.get.to_Node.get)

wh2 = WaterHeaterMixed.new(m)
wh2.addToNode(p.supplyOutletNode)
spm_sch2 = spm_sch.clone(m).to_SetpointManagerScheduled.get
spm_sch2.addToNode(p.supplyOutletNode)

m.save('1654_model.osm', true)

ft = OpenStudio::EnergyPlus::ForwardTranslator.new
w = ft.translateModel(m)

puts w.getObjectsByType("PlantEquipmentOperationSchemes")

puts w.getObjectsByType("PlantEquipmentOperation:HeatingLoad")
puts w.getObjectsByType("PlantEquipmentOperation:HeatingLoad")[0].getTarget(3).get

puts w.getObjectsByType("PlantEquipmentOperation:ComponentSetpoint")

w.save('1654_model.idf', true)

Output:

PlantEquipmentOperationSchemes,
  Plant Loop 1 Operation Schemes,         !- Name
  PlantEquipmentOperation:HeatingLoad,    !- Control Scheme Object Type 1
  Plant Loop 1 Heating Operation Scheme,  !- Control Scheme Name 1
  Always On Discrete,                     !- Control Scheme Schedule Name 1
  PlantEquipmentOperation:ComponentSetpoint, !- Control Scheme Object Type 2
  Plant Loop 1 Setpoint Operation Scheme, !- Control Scheme Name 2
  Always On Discrete;                     !- Control Scheme Schedule Name 2

PlantEquipmentOperation:HeatingLoad,
  Plant Loop 1 Heating Operation Scheme,  !- Name
  0,                                      !- Load Range Lower Limit 1 {W}
  1000000000,                             !- Load Range Upper Limit 1 {W}
  Plant Loop 1 Heating Equipment List;    !- Range Equipment List Name 1

PlantEquipmentList,
  Plant Loop 1 Heating Equipment List,    !- Name
  WaterHeater:Mixed,                      !- Equipment Object Type 1
  Water Heater Mixed 1,                   !- Equipment Name 1
  WaterHeater:Mixed,                      !- Equipment Object Type 2
  Water Heater Mixed 2;                   !- Equipment Name 2

PlantEquipmentOperation:ComponentSetpoint,
  Plant Loop 1 Setpoint Operation Scheme, !- Name
  WaterHeater:Mixed,                      !- Equipment Object Type 1
  Water Heater Mixed 1,                   !- Equipment Name 1
  Node 3,                                 !- Demand Calculation Node Name 1
  Node 7,                                 !- Setpoint Node Name 1
  Autosize,                               !- Component Flow Rate 1 {m3/s}
  Heating;                                !- Operation Type 1

[kbenne]

I agree two component operation schemes for the same component seems silly, but two different operation schemes for two different components is a thing right? I thought the issue I reported was a problem even with one operation scheme per component.

[jmarrec]

It's a thing to have multiple plant equipment operation schemes yes. But the PlantEquipmentOperationScheme is listing stuff in priority order: https://bigladdersoftware.com/epx/docs/9-5/input-output-reference/group-plant-condenser-control.html#plantequipmentoperationschemes

Here basically since these are both defaulted, the PlantEquipmentOperation:HeatingLoad applies to a range up to 1000000000 W (so basically "INFINITY"), and is listed first. As a result the PlantEquipmentOperation:ComponentSetpoint is never going to be applied. I don't think there's side effects to having it defined anyway, my question was more what is the actual intended behavior?

If I put a WaterHeaterMixed on a branch between the mixer and splitter:

• If I do not use a SPM:Scheduled (or else) on its outlet node, I think it's appropriate to add it to a PlantEquipmentOperation:HeatingLoad
• If I do use a SPM:Scheduled on its outlet node, which one do I want defaulted? HeatingLoad or ComponentSetpoint?

[jmarrec]

ping @kbenne

[jmarrec]

@kbenne I'd like to eventually reach a consensus on this one and either fix or close. Could you carve 15min in the coming weeks to think about it please? Otherwise I'll ping you in 6 months again ;)