EMS cannot override Headered Pumps Head correctly

asked 2023-12-09 23:05:13 -0500

Keigo's avatar

updated 2023-12-10 08:25:30 -0500

A bug report. When we try to override Pump Pressure Rise of HeaderedPumps:VariableSpeed or HeaderedPumps:ConstantSpeed with any value by EMS, Pump Electricity Rate becomes almost 0 W, probably because Pump Pressure Rise becoms almost 0 Pa.

I reproduced the bug with an ExampleFile HeaderedPumpsVarSpeed.idf. The idf file is here (V23-2-0). I added EMS as follows.

    Chilled Water Headered Pumps,  !- Name
    CW Supply Inlet Node,    !- Inlet Node Name
    CW Pumps Outlet Node,    !- Outlet Node Name
    autosize,                !- Total Design Flow Rate {m3/s}
    2,                       !- Number of Pumps in Bank
    SEQUENTIAL,              !- Flow Sequencing Control Scheme
    179352,                  !- Design Pump Head {Pa}
    autosize,                !- Design Power Consumption {W}
    0.9,                     !- Motor Efficiency
    0.0,                     !- Fraction of Motor Inefficiencies to Fluid Stream
    0,                       !- Coefficient 1 of the Part Load Performance Curve
    1,                       !- Coefficient 2 of the Part Load Performance Curve
    0,                       !- Coefficient 3 of the Part Load Performance Curve
    0,                       !- Coefficient 4 of the Part Load Performance Curve
    0.1,                     !- Minimum Flow Rate Fraction
    INTERMITTENT,            !- Pump Control Type
    CoolingPumpAvailSched,   !- Pump Flow Rate Schedule Name
    ,                        !- Zone Name
    ,                        !- Skin Loss Radiative Fraction
    PowerPerFlowPerPressure, !- Design Power Sizing Method
    ,                        !- Design Electric Power per Unit Flow Rate {W/(m3/s)}
    ,                        !- Design Shaft Power per Unit Flow Rate per Unit Head {W/((m3/s)-Pa)}
    Pump Energy;             !- End-Use Subcategory

    ChilledWaterHeaderedPumps_PressureRise,  !- Name
    Chilled Water Headered Pumps,  !- Actuated Component Unique Name
    Pump,                    !- Actuated Component Type
    Pump Pressure Rise;      !- Actuated Component Control Type

    EMS_PCM_PumpPressureOverride,  !- Name
    InsideHVACSystemIterationLoop,  !- EnergyPlus Model Calling Point
    EMS_Program_PumpPressureRiseOverride;  !- Program Name 1

    EMS_Program_PumpPressureRiseOverride,  !- Name
    SET ChilledWaterHeaderedPumps_PressureRise = 358704;  !- Program Line 1

I doubled the Pump Pressure Rise of Chilled Water Headered Pumps i.e. I changed it from 179352Pa to 358704Pa. The original Design Power Consumption of the Chilled Water Headered Pumps is 353.18 W. So, the Pump Electricity Rate after I added EMS is supposed to be between 0W to 706.36 W. However, the result shows that it is 1.25872157206094E-306 W (the red line on the chart below).

image description

The bug does not occur with Pump:VariableSpeed and Pump:ConstantSpeed. Only headered pumps have the bug.

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Keigo's avatar Keigo  ( 2023-12-12 00:13:02 -0500 )edit