Buildings.Experimental.DHC.Plants.Steam
Package with models for steam plants
Information
This package contains models for plants producing steam.
Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
Package Content
| Name | Description |
|---|---|
 SingleBoiler
|
A generic steam plant with a single boiler that discharges saturated steam |
 Examples
|
Example models for steam plants |
 BaseClasses
|
Package with base classes for Buildings.Experimental.DHC.Plants.Steam |
Buildings.Experimental.DHC.Plants.Steam.SingleBoiler
A generic steam plant with a single boiler that discharges
saturated steam
Information
This is a generic steam plant model that can be used in district heating system simulations. The model contains a feedwater tank, feedwater pump, check valve, and a boiler. The boiler is designed to discharge saturated steam vapor. For controls, the feedwater pump maintains the water volume setpoint in the drum boiler, while the boiler control maintains the discharge pressure setpoint.
Extends from Buildings.Experimental.DHC.Plants.BaseClasses.PartialPlant (Partial class for modeling a plant).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | Water | Service side medium | |
| replaceable package MediumHea_b | Water | Service side medium at heating supply | |
| Generic | fue[nFue] | {fueBoi} | Fuel type |
| Generic | fueBoi | Buildings.Fluid.Data.Fuels.N... | Boiler fuel type |
| MassFlowRate | m_flow_nominal | 1 | Nominal mass flow rate [kg/s] |
| Power | Q_flow_nominal | m_flow_nominal*(MediumHea_b.... | Nominal heating power [W] |
| AbsolutePressure | pSteSet | 300000 | Steam pressure setpoint [Pa] |
| AbsolutePressure | pTanFW | 101325 | Pressure of feedwater tank [Pa] |
| Volume | VBoiWatSet | VBoi/2 | Setpoint for liquid water volume in the boiler [m3] |
| Volume | VBoi | 3 | Total drum volume of steam boiler [m3] |
| Real | boiSca | 1.25 | Boiler heat capacity scaling factor |
| Generic | per | per(pressure(V_flow=(m_flow_... | Performance data for the feedwater pump |
| Configuration | |||
| DistrictSystemType | typ | Buildings.Experimental.DHC.T... | Type of district system |
| Boolean | have_fan | false | Set to true if fan power is computed |
| Boolean | have_pum | true | Set to true if pump power is computed |
| Boolean | have_eleHea | false | Set to true if the plant has electric heating system |
| Integer | nFue | 1 | Number of fuel types (0 means no combustion system) |
| Boolean | have_eleCoo | false | Set to true if the plant has electric cooling system |
| Boolean | have_weaBus | false | Set to true to use a weather bus |
| Assumptions | |||
| Boolean | allowFlowReversal | false | Set to true to allow flow reversal in service lines |
| Dynamics | |||
| Mass | mDry | 1.5E-3*Q_flow_nominal | Mass of boiler that will be lumped to water heat capacity [kg] |
| Equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Dynamics | massDynamics | energyDynamics | Type of mass balance: dynamic (3 initialization options) or steady state |
| Initialization | |||
| Volume | VTanFW_start | 1 | Setpoint for liquid water volume in the boiler [m3] |
| AbsolutePressure | pBoi_start | pTanFW | Start value of boiler pressure [Pa] |
| Real | yPum_start | 0.7 | Initial value of pump speed |
| Control | |||
| Boiler | |||
| SimpleController | controllerTypeBoi | Modelica.Blocks.Types.Simple... | Type of controller |
| Real | kBoi | 10 | Gain of controller |
| Time | TiBoi | 120 | Time constant of Integrator block [s] |
| Time | TdBoi | 10 | Time constant of Derivative block [s] |
| Real | wpBoi | 1 | Set-point weight for Proportional block (0..1) |
| Real | wdBoi | 0 | Set-point weight for Derivative block (0..1) |
| Real | NiBoi | 0.9 | Ni*Ti is time constant of anti-windup compensation |
| Real | NdBoi | 10 | The higher Nd, the more ideal the derivative block |
| Pump | |||
| SimpleController | controllerTypePum | Modelica.Blocks.Types.Simple... | Type of controller |
| Real | kPum | 5 | Gain of controller |
| Time | TiPum | 120 | Time constant of Integrator block [s] |
| Time | TdPum | 0.1 | Time constant of Derivative block [s] |
| Real | wpPum | 1 | Set-point weight for Proportional block (0..1) |
| Real | wdPum | 0 | Set-point weight for Derivative block (0..1) |
| Real | NiPum | 0.9 | Ni*Ti is time constant of anti-windup compensation |
| Real | NdPum | 10 | The higher Nd, the more ideal the derivative block |
Connectors
| Type | Name | Description |
|---|---|---|
| replaceable package MediumHea_b | Service side medium at heating supply | |
| FluidPort_a | port_aSerAmb | Fluid connector for ambient water service supply line |
| FluidPort_b | port_bSerAmb | Fluid connector for ambient water service return line |
| FluidPort_a | port_aSerHea | Fluid connector for heating service supply line |
| FluidPort_b | port_bSerHea | Fluid connector for heating service return line |
| FluidPort_a | port_aSerCoo | Fluid connector for cooling service supply line |
| FluidPort_b | port_bSerCoo | Fluid connector for cooling service return line |
| Bus | weaBus | Weather data bus |
| output RealOutput | PHea | Power drawn by heating system [W] |
| output RealOutput | PCoo | Power drawn by cooling system [W] |
| output RealOutput | PFan | Power drawn by fan motors [W] |
| output RealOutput | PPum | Power drawn by pump motors [W] |
| output RealOutput | QFue_flow | Fuel energy input rate [W] |
Modelica definition
model SingleBoiler "A generic steam plant with a single boiler that discharges
saturated steam"
extends Buildings.Experimental.DHC.Plants.BaseClasses.PartialPlant(
final typ=Buildings.Experimental.DHC.Types.DistrictSystemType.HeatingGeneration1,
redeclare replaceable package MediumHea_b=Buildings.Media.Steam,
final have_fan=false,
final have_pum=true,
final nFue=1,
final fue={fueBoi},
final have_eleHea=false,
final have_eleCoo=false,
final have_weaBus=false);
parameter Buildings.Fluid.Data.Fuels.Generic fueBoi=
Buildings.Fluid.Data.Fuels.NaturalGasLowerHeatingValue()
"Boiler fuel type";
// Nominal values
parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=1
"Nominal mass flow rate";
parameter Modelica.Units.SI.Power Q_flow_nominal=m_flow_nominal*(
MediumHea_b.specificEnthalpy(MediumHea_b.setState_pTX(
p=pSteSet,
T=TSat,
X=MediumHea_b.X_default)) -
Medium.specificEnthalpy(Medium.setState_pTX(
p=pSteSet,
T=TSat,
X=Medium.X_default)))
"Nominal heating power";
// Setpoints
parameter Modelica.Units.SI.AbsolutePressure pSteSet=300000
"Steam pressure setpoint";
final parameter Modelica.Units.SI.Temperature TSat=
MediumHea_b.saturationTemperature(pSteSet)
"Saturation temperature at pressure setpoint";
parameter Modelica.Units.SI.AbsolutePressure pTanFW=101325
"Pressure of feedwater tank";
parameter Modelica.Units.SI.Volume VBoiWatSet=VBoi/2
"Setpoint for liquid water volume in the boiler";
// System sizing
parameter Modelica.Units.SI.Volume VBoi=3
"Total drum volume of steam boiler";
parameter Real boiSca = 1.25 "Boiler heat capacity scaling factor";
parameter Modelica.Units.SI.Mass mDry = 1.5E-3*Q_flow_nominal
"Mass of boiler that will be lumped to water heat capacity";
parameter Buildings.Fluid.Movers.Data.Generic per(
pressure(
V_flow=(m_flow_nominal/1000)*{0.4,0.6,0.8,1.0},
dp=(pSteSet-pTanFW)*{1.34,1.27,1.17,1.0}))
"Performance data for the feedwater pump";
// Initial conditions
parameter Modelica.Units.SI.Volume VTanFW_start=1
"Setpoint for liquid water volume in the boiler";
parameter Modelica.Media.Interfaces.Types.AbsolutePressure pBoi_start=pTanFW
"Start value of boiler pressure";
parameter Real yPum_start=0.7 "Initial value of pump speed";
// Dynamics
parameter Modelica.Fluid.Types.Dynamics energyDynamics=
Modelica.Fluid.Types.Dynamics.DynamicFreeInitial
"Type of energy balance: dynamic (3 initialization options) or steady state";
parameter Modelica.Fluid.Types.Dynamics massDynamics=energyDynamics
"Type of mass balance: dynamic (3 initialization options) or steady state";
// Boiler controller
parameter Modelica.Blocks.Types.SimpleController controllerTypeBoi=
Modelica.Blocks.Types.SimpleController.PI "Type of controller";
parameter Real kBoi(min=0) = 10 "Gain of controller";
parameter Modelica.Units.SI.Time TiBoi(min=Modelica.Constants.small)=120
"Time constant of Integrator block";
parameter Modelica.Units.SI.Time TdBoi(min=0)=10
"Time constant of Derivative block";
parameter Real wpBoi(min=0) = 1 "Set-point weight for Proportional block (0..1)";
parameter Real wdBoi(min=0) = 0 "Set-point weight for Derivative block (0..1)";
parameter Real NiBoi(min=100*Modelica.Constants.eps) = 0.9
"Ni*Ti is time constant of anti-windup compensation";
parameter Real NdBoi(min=100*Modelica.Constants.eps) = 10
"The higher Nd, the more ideal the derivative block";
// Feedwater pump controller
parameter Modelica.Blocks.Types.SimpleController controllerTypePum=
Modelica.Blocks.Types.SimpleController.PI "Type of controller";
parameter Real kPum(min=0) = 5 "Gain of controller";
parameter Modelica.Units.SI.Time TiPum(min=Modelica.Constants.small)=120
"Time constant of Integrator block";
parameter Modelica.Units.SI.Time TdPum(min=0)=0.1
"Time constant of Derivative block";
parameter Real wpPum(min=0) = 1 "Set-point weight for Proportional block (0..1)";
parameter Real wdPum(min=0) = 0 "Set-point weight for Derivative block (0..1)";
parameter Real NiPum(min=100*Modelica.Constants.eps) = 0.9
"Ni*Ti is time constant of anti-windup compensation";
parameter Real NdPum(min=100*Modelica.Constants.eps) = 10
"The higher Nd, the more ideal the derivative block";
// Pump can have reverse flow at start up
Buildings.Fluid.Movers.SpeedControlled_y pumFW(
redeclare final package Medium = Medium,
final energyDynamics=energyDynamics,
p_start=pTanFW,
final allowFlowReversal=allowFlowReversal,
final per=per,
final y_start=yPum_start)
"Feedwater pump";
// At start up, water leaves port_a, see Buildings.Experimental.DHC.Examples.Steam.SingleBoiler
Buildings.Experimental.DHC.Plants.Steam.BaseClasses.BoilerPolynomial boi(
redeclare final package MediumSte = MediumHea_b,
redeclare final package MediumWat = Medium,
final energyDynamics=energyDynamics,
final massDynamics=massDynamics,
final allowFlowReversal=allowFlowReversal,
final p_start=pTanFW,
fixed_p_start=true,
final fue=fueBoi,
final m_flow_nominal=m_flow_nominal,
final dp_nominal=3000,
final Q_flow_nominal=Q_flow_nominal*boiSca,
final V=VBoi,
final mDry=mDry)
"Steam boiler";
Buildings.Controls.Continuous.LimPID conPum(
final controllerType=controllerTypePum,
final k=kPum,
final Ti=TiPum,
final Td=TdPum,
final wp=wpPum,
final wd=wdPum,
final Ni=NiPum,
final Nd=NdPum,
initType=Modelica.Blocks.Types.Init.InitialOutput,
y_start=yPum_start)
"Pump control";
Modelica.Blocks.Math.Gain VNor(final k=1/VBoiWatSet)
"Normalized volume setpoint";
Buildings.Controls.Continuous.LimPID conBoi(
final controllerType=controllerTypeBoi,
final k=kBoi,
final Ti=TiBoi,
final Td=TdBoi,
final wp=wpBoi,
final wd=wdBoi,
final Ni=NiBoi,
final Nd=NdBoi)
"Boiler control";
Modelica.Blocks.Math.Gain PNor(final k=1/pSteSet)
"Normalized pressure setpoint";
Buildings.Fluid.Sensors.Pressure senPreSte(
redeclare final package Medium = MediumHea_b)
"Steam pressure sensor";
Modelica.Blocks.Sources.Constant uni(final k=1) "Unitary";
Buildings.Fluid.Storage.ExpansionVessel tanFW(
redeclare final package Medium = Medium,
final V_start=VTanFW_start,
final p_start=pTanFW)
"Feedwater tank";
Buildings.Fluid.FixedResistances.CheckValve cheVal(
redeclare final package Medium = Medium,
final allowFlowReversal=allowFlowReversal,
final m_flow_nominal=m_flow_nominal,
dpValve_nominal=6000,
rhoStd=Medium.density_pTX(
pSteSet,
MediumHea_b.saturationTemperature(pSteSet),
Medium.X_default))
"Check valve";
equation
connect(port_aSerHea, pumFW.port_a);
connect(boi.port_b, port_bSerHea);
connect(conPum.y, pumFW.y);
connect(uni.y, conPum.u_s);
connect(VNor.y, conPum.u_m);
connect(boi.VLiq, VNor.u);
connect(senPreSte.port, boi.port_b);
connect(senPreSte.p, PNor.u);
connect(PNor.y, conBoi.u_m);
connect(conBoi.y, boi.y);
connect(uni.y, conBoi.u_s);
connect(QFue_flow, boi.QFueFlo);
connect(PPum, pumFW.P);
connect(tanFW.port_a, pumFW.port_a);
connect(pumFW.port_b, cheVal.port_a);
connect(cheVal.port_b, boi.port_a);
end SingleBoiler;