Buildings.DHC.Plants.Cooling

Package of models for central cooling production

Information

This package contains models for central plants producing chilled water.

Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).

Package Content

Name	Description
ElectricChillerParallel	District cooling plant model
StoragePlant	Model of a storage plant with a chiller and a CHW tank
Controls	Package of control sequences for cooling plants
Subsystems	Package of models for subsystems of cooling plants
Examples	Example models integrating multiple components
BaseClasses	Package containing base classes

Buildings.DHC.Plants.Cooling.ElectricChillerParallel

District cooling plant model

Buildings.DHC.Plants.Cooling.ElectricChillerParallel

Information

This model implements a generic district central cooling plant as illustrated in the schematics below.

The cooling is provided by two parallel chillers instantiated from Buildings.Applications.BaseClasses.Equipment.ElectricChillerParallel.
The chilled water bypass loop is controlled to ensure a minimum flow of chilled water running through the chillers all the time.
The condenser water is cooled by two parallel cooling towers with a bypass loop. See Buildings.DHC.Plants.Cooling.Subsystems.CoolingTowersWithBypass for the details of the modeling of the cooling towers.
The chilled water loop is equipped with two parallel constant speed pumps, which run one-and-one with each chiller. The condenser water pumps are constant speed with prescribed mass flow rates.
The plant operates when it receives an on signal from the external control.

The staging of the chillers is based on the calculated cooling load.

See Buildings.DHC.Plants.Cooling.Controls.ChillerStage for the detailed control logic.

System schematics .

Extends from Buildings.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]		Fuel type
PressureDifference	dpCooTowVal_nominal		Nominal pressure difference of the cooling tower valve [Pa]
Configuration
DistrictSystemType	typ	Buildings.DHC.Types.District...	Type of district system
Boolean	have_fan	true	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	0	Number of fuel types (0 means no combustion system)
Boolean	have_eleCoo	true	Set to true if the plant has electric cooling system
Boolean	have_weaBus	true	Set to true to use a weather bus
Chiller
Generic	perChi	redeclare parameter Building...	Performance data of chiller
MassFlowRate	mCHW_flow_nominal		Nominal chilled water mass flow rate [kg/s]
Pressure	dpCHW_nominal		Pressure difference at the chilled water side [Pa]
HeatFlowRate	QChi_nominal		Nominal cooling capacity of single chiller (negative means cooling) [W]
MassFlowRate	mMin_flow		Minimum mass flow rate of single chiller [kg/s]
Cooling Tower
MassFlowRate	mCW_flow_nominal		Nominal condenser water mass flow rate [kg/s]
Pressure	dpCW_nominal		Pressure difference at the condenser water side [Pa]
Temperature	TAirInWB_nominal		Nominal air wetbulb temperature [K]
Temperature	TCW_nominal		Nominal condenser water temperature at tower inlet [K]
TemperatureDifference	dT_nominal		Temperature difference between inlet and outlet of the tower [K]
TemperatureDifference	dTApp		Approach temperature [K]
Temperature	TMin		Minimum allowed water temperature entering chiller [K]
Power	PFan_nominal		Fan power [W]
Pump
Generic	perCHWPum	redeclare parameter Building...	Performance data of chilled water pump
Generic	perCWPum	redeclare parameter Building...	Performance data of condenser water pump
Pressure	dpCHWPumVal_nominal		Nominal pressure drop of chilled water pump valve [Pa]
Pressure	dpCWPumVal_nominal		Nominal pressure drop of condenser water pump valve [Pa]
Control Settings
Time	tWai		Waiting time [s]
Assumptions
Boolean	allowFlowReversal	false	Set to true to allow flow reversal in service lines
Dynamics
Pump
Time	tau	1	Pump time constant at nominal flow (if energyDynamics <> SteadyState) [s]
Boolean	use_inputFilter	false	= true, if pump speed is filtered with a 2nd order CriticalDamping filter
Time	riseTimePump	30	Pump rise time of the filter (time to reach 99.6 % of the speed) [s]
Init	init	Modelica.Blocks.Types.Init.I...	Type of initialization for pumps (no init/steady state/initial state/initial output)
Real	yCHWP_start[numChi]	fill(0, numChi)	Initial value of CHW pump signals
Real	yCWP_start[numChi]	fill(0, numChi)	Initial value of CW pump signals
Conservation equations
Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamic...	Type of energy balance: dynamic (3 initialization options) or steady state
Advanced
Dynamics
Dynamics	massDynamics	energyDynamics	Type of mass balance: dynamic (3 initialization options) or steady state, must be steady state if energyDynamics is steady state

Connectors

Type	Name	Description
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]
input BooleanInput	on	On signal of the plant
input RealInput	TCHWSupSet	Set point for chilled water supply temperature [K]

Modelica definition

model ElectricChillerParallel "District cooling plant model" extends Buildings.DHC.Plants.BaseClasses.PartialPlant( have_eleCoo=true, have_pum=true, have_fan=true, have_weaBus=true, typ=Buildings.DHC.Types.DistrictSystemType.Cooling); // chiller parameters final parameter Integer numChi=2 "Number of chillers"; replaceable parameter Buildings.Fluid.Chillers.Data.ElectricEIR.Generic perChi "Performance data of chiller"; parameter Modelica.Units.SI.MassFlowRate mCHW_flow_nominal "Nominal chilled water mass flow rate"; parameter Modelica.Units.SI.Pressure dpCHW_nominal "Pressure difference at the chilled water side"; parameter Modelica.Units.SI.HeatFlowRate QChi_nominal(max=0) "Nominal cooling capacity of single chiller (negative means cooling)"; parameter Modelica.Units.SI.MassFlowRate mMin_flow "Minimum mass flow rate of single chiller"; // cooling tower parameters parameter Modelica.Units.SI.MassFlowRate mCW_flow_nominal "Nominal condenser water mass flow rate"; parameter Modelica.Units.SI.Pressure dpCW_nominal "Pressure difference at the condenser water side"; parameter Modelica.Units.SI.Temperature TAirInWB_nominal "Nominal air wetbulb temperature"; parameter Modelica.Units.SI.Temperature TCW_nominal "Nominal condenser water temperature at tower inlet"; parameter Modelica.Units.SI.TemperatureDifference dT_nominal "Temperature difference between inlet and outlet of the tower"; parameter Modelica.Units.SI.TemperatureDifference dTApp "Approach temperature"; parameter Modelica.Units.SI.Temperature TMin "Minimum allowed water temperature entering chiller"; parameter Modelica.Units.SI.Power PFan_nominal "Fan power"; // pump parameters replaceable parameter Buildings.Fluid.Movers.Data.Generic perCHWPum constrainedby Buildings.Fluid.Movers.Data.Generic "Performance data of chilled water pump"; replaceable parameter Buildings.Fluid.Movers.Data.Generic perCWPum constrainedby Buildings.Fluid.Movers.Data.Generic "Performance data of condenser water pump"; parameter Modelica.Units.SI.Pressure dpCHWPumVal_nominal "Nominal pressure drop of chilled water pump valve"; parameter Modelica.Units.SI.Pressure dpCWPumVal_nominal "Nominal pressure drop of condenser water pump valve"; parameter Modelica.Units.SI.Time tau=1 "Pump time constant at nominal flow (if energyDynamics <> SteadyState)"; parameter Boolean use_inputFilter=false "= true, if pump speed is filtered with a 2nd order CriticalDamping filter"; parameter Modelica.Units.SI.Time riseTimePump=30 "Pump rise time of the filter (time to reach 99.6 % of the speed)"; parameter Modelica.Blocks.Types.Init init=Modelica.Blocks.Types.Init.InitialOutput "Type of initialization for pumps (no init/steady state/initial state/initial output)"; parameter Real[numChi] yCHWP_start=fill(0,numChi) "Initial value of CHW pump signals"; parameter Real[numChi] yCWP_start=fill(0,numChi) "Initial value of CW pump signals"; parameter Modelica.Units.SI.PressureDifference dpCooTowVal_nominal "Nominal pressure difference of the cooling tower valve"; // control settings parameter Modelica.Units.SI.Time tWai "Waiting time"; // 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, must be steady state if energyDynamics is steady state"; Modelica.Blocks.Interfaces.BooleanInput on "On signal of the plant"; Modelica.Blocks.Interfaces.RealInput TCHWSupSet( final unit="K", displayUnit="degC") "Set point for chilled water supply temperature"; Buildings.Applications.BaseClasses.Equipment.ElectricChillerParallel mulChiSys( final use_inputFilter=use_inputFilter, final per=fill( perChi, numChi), final m1_flow_nominal=mCW_flow_nominal, final m2_flow_nominal=mCHW_flow_nominal, final dp1_nominal=dpCW_nominal/2, final dp2_nominal=dpCHW_nominal, final num=numChi, redeclare final package Medium1=Medium, redeclare final package Medium2=Medium) "Chillers connected in parallel"; Buildings.DHC.Plants.Cooling.Subsystems.CoolingTowersWithBypass cooTowWitByp( redeclare final package Medium=Medium, final num=numChi, final m_flow_nominal=mCW_flow_nominal, final use_inputFilter=use_inputFilter, final dp_nominal=dpCW_nominal/2, final dpValve_nominal = dpCooTowVal_nominal, final TAirInWB_nominal=TAirInWB_nominal, final TWatIn_nominal=TCW_nominal, final dT_nominal=dT_nominal, final dTApp=dTApp, final PFan_nominal=PFan_nominal, final TMin=TMin) "Cooling towers with bypass valve"; Buildings.Applications.BaseClasses.Equipment.FlowMachine_y pumCHW( redeclare final package Medium=Medium, final per=fill( perCHWPum, numChi), yValve_start=fill( 1, numChi), final tau=tau, final use_inputFilter=use_inputFilter, final riseTimePump=riseTimePump, final init=init, final yPump_start=yCHWP_start, final energyDynamics=energyDynamics, final m_flow_nominal=mCHW_flow_nominal, final dpValve_nominal=dpCHWPumVal_nominal, final num=numChi) "Chilled water pumps"; Buildings.Applications.BaseClasses.Equipment.FlowMachine_m pumCW( redeclare final package Medium=Medium, final per=fill( perCWPum, numChi), final tau=tau, final use_inputFilter=use_inputFilter, final riseTimePump=riseTimePump, final init=init, final yPump_start=yCWP_start, final energyDynamics=energyDynamics, final m_flow_nominal=mCW_flow_nominal, final dpValve_nominal=dpCWPumVal_nominal, final num=numChi) "Condenser water pumps"; Buildings.Fluid.Actuators.Valves.TwoWayEqualPercentage valByp( redeclare final package Medium=Medium, final allowFlowReversal=false, final m_flow_nominal=mCHW_flow_nominal, final dpValve_nominal=dpCHWPumVal_nominal, final use_inputFilter=true, riseTime=60) "Chilled water bypass valve"; Buildings.Fluid.Sensors.TemperatureTwoPort senTCHWSup( redeclare final package Medium=Medium, final m_flow_nominal=mCHW_flow_nominal) "Chilled water supply temperature"; Buildings.DHC.Plants.Cooling.Controls.ChillerStage chiStaCon( final tWai=tWai, final QChi_nominal=QChi_nominal) "Chiller staging controller"; Buildings.Fluid.Sensors.TemperatureTwoPort senTCHWRet( redeclare final package Medium=Medium, final m_flow_nominal=mCHW_flow_nominal) "Chilled water return temperature"; Buildings.Fluid.Sources.Boundary_pT expTanCW( redeclare final package Medium=Medium, p=300000, nPorts=1) "Condenser water expansion tank"; Buildings.Fluid.Sources.Boundary_pT expTanCHW( redeclare final package Medium=Medium, p=300000, nPorts=1) "Chilled water expansion tank"; Buildings.Fluid.Sensors.MassFlowRate senMasFlo( redeclare final package Medium=Medium) "Chilled water return mass flow"; Buildings.Controls.OBC.CDL.Conversions.BooleanToReal chiOn[numChi] "Convert chiller on signal from boolean to real"; Buildings.Controls.OBC.CDL.Reals.MultiSum totPPum( nin=4) "Total pump power"; Buildings.Controls.OBC.CDL.Reals.MultiSum totPFan( nin=2) "Total fan power"; Buildings.Controls.OBC.CDL.Reals.MultiSum totPCoo( nin=2) "Total cooling power"; Buildings.Fluid.FixedResistances.Junction joiCHWRet( redeclare final package Medium=Medium, final m_flow_nominal=mCHW_flow_nominal .* {1,-1,1}, energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState, dp_nominal={0,0,0}) "Flow joint for the chilled water return side"; Buildings.Fluid.FixedResistances.Junction splCHWSup( redeclare final package Medium=Medium, final m_flow_nominal=mCHW_flow_nominal .* {1,-1,-1}, energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState, dp_nominal={0,0,0}) "Flow splitter for the chilled water supply side"; Buildings.DHC.Plants.Cooling.Controls.ChilledWaterBypass chiBypCon( final numChi=numChi, final mMin_flow=mMin_flow, k=1, Ti=120) "Chilled water bypass control"; Fluid.Sensors.MassFlowRate senMasFloCHW( redeclare final package Medium = Medium) "Total chilled water pump mass flow rate"; protected final parameter Medium.ThermodynamicState sta_default=Medium.setState_pTX( T=Medium.T_default, p=Medium.p_default, X=Medium.X_default) "Medium state at default properties"; final parameter Modelica.Units.SI.SpecificHeatCapacity cp_default= Medium.specificHeatCapacityCp(sta_default) "Specific heat capacity of the fluid"; initial equation assert(energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState or massDynamics == Modelica.Fluid.Types.Dynamics.SteadyState, "In " + getInstanceName() + ": energyDynamics is selected as steady state, and therefore massDynamics must also be steady-state."); equation connect(cooTowWitByp.port_b,pumCW.port_a); connect(on,chiStaCon.on); connect(pumCHW.port_b,mulChiSys.port_a2); connect(pumCW.port_b,mulChiSys.port_a1); connect(mulChiSys.port_b1,cooTowWitByp.port_a); connect(expTanCW.ports[1],pumCW.port_a); connect(senTCHWRet.port_b,senMasFlo.port_a); connect(chiStaCon.y,mulChiSys.on); connect(chiStaCon.y,chiOn.u); connect(chiOn.y,pumCW.u); connect(chiStaCon.y,cooTowWitByp.on); connect(weaBus.TWetBul,cooTowWitByp.TWetBul); connect(port_aSerCoo,senTCHWRet.port_a); connect(senTCHWSup.port_b,port_bSerCoo); connect(TCHWSupSet,mulChiSys.TSet); connect(totPPum.y,PPum); connect(pumCW.P,totPPum.u[1:2]); connect(pumCHW.P,totPPum.u[3:4]); connect(totPFan.y,PFan); connect(cooTowWitByp.PFan,totPFan.u[1:2]); connect(totPCoo.y,PCoo); connect(mulChiSys.P,totPCoo.u[1:2]); connect(splCHWSup.port_3,senTCHWSup.port_a); connect(senTCHWRet.T,chiStaCon.TChiWatRet); connect(senTCHWSup.T,chiStaCon.TChiWatSup); connect(senMasFlo.m_flow,chiStaCon.mFloChiWat); connect(chiStaCon.y,chiBypCon.chiOn); connect(senMasFlo.port_b, joiCHWRet.port_3); connect(valByp.port_b, joiCHWRet.port_1); connect(senMasFloCHW.m_flow, chiBypCon.mFloChi); connect(valByp.port_a, splCHWSup.port_2); connect(joiCHWRet.port_2, pumCHW.port_a); connect(expTanCHW.ports[1], pumCHW.port_a); connect(mulChiSys.port_b2, senMasFloCHW.port_a); connect(senMasFloCHW.port_b, splCHWSup.port_1); connect(chiBypCon.y, valByp.y); connect(chiOn.y, pumCHW.u); end ElectricChillerParallel;

Buildings.DHC.Plants.Cooling.StoragePlant

Model of a storage plant with a chiller and a CHW tank

Buildings.DHC.Plants.Cooling.StoragePlant

Information

This model encompasses the components of a chilled water storage plant. It includes a flow-controlled primary pump, a stratefied storage tank, a reversible connection with the district network, and related controls to coordinate charging and discharging of the tank. The chiller is intentionally excluded in this component so that it can be otherwise chosen and configured. The tank in this plant can be charged by its local chiller or by a remote chiller on the same CHW district network.

System Concept Example

An example usage of this model within a district network is implemented in Buildings.DHC.Plants.Cooling.Examples.StoragePlantDualSource. Shown in the schematic below, it has two CHW plants and three users.

Plant 1 only has a chiller. The supply pump, P1, is controlled to ensure that all users have enough pressure head. This represents a remote chiller plant, referenced above.
Plant 2 has a chiller and a stratified CHW tank and is represented by this model. The storage plant has a reversible connection to the district network that can either pump water to the network from the plant using the pump P_sec, or throttle water from the pressurised network to charge the tank.

SystemConcept

Control Signals

The plants are controlled as follows:

In plant 1, for the sake of this discussion, assume the chiller is always on. The speed-controlled pump ensures that the users have enough pressure head at all times. This includes plant 2 when its tank is charged remotely by plant 1 and it acts like an energy consumer.
For plant 2:
- In the chiller loop, chiller 2 and its primary pump P_pri are on whenever needed (for charging the tank or producing CHW to the network). Otherwise, they are commanded off.
- The system receives one of the following three commands regarding the tank: charge, discharge, or no action. The tank controller returns status signals. It can be empty, charged, or in-between. The command to tank may be disregarded. For example, if the tank is receiving a discharge command but it is already empty, it will not discharge which would let warm return water directly into the supply side. See the Implementation section for details.
- The reversible connection between plant 2 and the district network modulates the flow rate needed by plant 2.
  - When the storage plant produces CHW, P_sec receives a speed control signal from the same PI controller as P1 in plant 1.
  - When the storage plant is charged remotely, the pressure-independent valve is controlled to maintain a constant flow from the pressurised network to the storage tank.
  - Otherwise, the connection cuts off flow to isolate plant 2 from the district network.

ControlSignals

Implementation

The flow control of the storage plant is implemented as a state graph in Buildings.DHC.Plants.Cooling.Controls.FlowControl.

Extends from Buildings.Fluid.Interfaces.PartialFourPort (Partial model with four ports).

Parameters

Type	Name	Default	Description
replaceable package Medium1		PartialMedium	Medium 1 in the component
replaceable package Medium2		PartialMedium	Medium 2 in the component
replaceable package Medium		Modelica.Media.Interfaces.Pa...	Medium package
Nominal values
MassFlowRate	m_flow_nominal	mTan_flow_nominal + mChi_flo...	Nominal mass flow rate [kg/s]
MassFlowRate	mTan_flow_nominal		Nominal mass flow rate for CHW tank branch [kg/s]
MassFlowRate	mChi_flow_nominal		Nominal mass flow rate for CHW chiller branch [kg/s]
PressureDifference	dpPum_nominal		Nominal pressure difference for secondary pump sizing [Pa]
PressureDifference	dpVal_nominal		Nominal pressure difference for return valve sizing [Pa]
Temperature	T_CHWS_nominal	7 + 273.15	Nominal temperature of CHW supply [K]
Temperature	T_CHWR_nominal	12 + 273.15	Nominal temperature of CHW return [K]
Assumptions
Boolean	allowFlowReversal1	true	= false to simplify equations, assuming, but not enforcing, no flow reversal for medium 1
Boolean	allowFlowReversal2	true	= false to simplify equations, assuming, but not enforcing, no flow reversal for medium 2

Connectors

Type	Name	Description
replaceable package Medium1		Medium 1 in the component
replaceable package Medium2		Medium 2 in the component
FluidPort_a	port_a1	Fluid connector a1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_b	port_b1	Fluid connector b1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_a	port_a2	Fluid connector a2 (positive design flow direction is from port_a2 to port_b2)
FluidPort_b	port_b2	Fluid connector b2 (positive design flow direction is from port_a2 to port_b2)
replaceable package Medium		Medium package
input BooleanInput	chiEnaSta	Chiller enable status, true if chiller is enabled
input IntegerInput	com	Command: 1 = charge tank, 2 = no command, 3 = discharge from tank
input BooleanInput	hasLoa	Set to true if the district has a load
input RealInput	yPum	Normalized speed signal for the secondary pump [1]
output RealOutput	dp	Pressure drop accross the connection (measured) [Pa]
output BooleanOutput	isChaRem	Is operated for remote charging

Modelica definition

model StoragePlant "Model of a storage plant with a chiller and a CHW tank" extends Buildings.Fluid.Interfaces.PartialFourPort( redeclare final package Medium1 = Medium, redeclare final package Medium2 = Medium); replaceable package Medium = Modelica.Media.Interfaces.PartialMedium "Medium package"; parameter Modelica.Units.SI.MassFlowRate m_flow_nominal= mTan_flow_nominal+mChi_flow_nominal "Nominal mass flow rate"; parameter Modelica.Units.SI.MassFlowRate mTan_flow_nominal(min=0) "Nominal mass flow rate for CHW tank branch"; parameter Modelica.Units.SI.MassFlowRate mChi_flow_nominal(min=0) "Nominal mass flow rate for CHW chiller branch"; parameter Modelica.Units.SI.PressureDifference dpPum_nominal "Nominal pressure difference for secondary pump sizing"; parameter Modelica.Units.SI.PressureDifference dpVal_nominal "Nominal pressure difference for return valve sizing"; parameter Modelica.Units.SI.Temperature T_CHWS_nominal( final displayUnit="degC")= 7+273.15 "Nominal temperature of CHW supply"; parameter Modelica.Units.SI.Temperature T_CHWR_nominal( final displayUnit="degC")= 12+273.15 "Nominal temperature of CHW return"; Buildings.Fluid.Movers.Preconfigured.FlowControlled_m_flow pumPri( redeclare final package Medium = Medium, final addPowerToMedium=false, final m_flow_nominal=mChi_flow_nominal, final dp_nominal=chi2PreDro.dp_nominal) "Primary CHW pump"; Buildings.Fluid.FixedResistances.PressureDrop chi2PreDro( redeclare final package Medium = Medium, final m_flow_nominal=mChi_flow_nominal, dp_nominal=0.1*dpPum_nominal) "Pressure drop of the chiller loop"; Buildings.DHC.Plants.Cooling.BaseClasses.TankBranch tanBra( redeclare final package Medium = Medium, final m_flow_nominal=m_flow_nominal, final mTan_flow_nominal=mTan_flow_nominal, final mChi_flow_nominal=mChi_flow_nominal, final T_CHWS_nominal=T_CHWS_nominal, final T_CHWR_nominal=T_CHWR_nominal, VTan=0.8, hTan=3, dIns=0.3) "Tank branch, tank can be charged remotely"; Buildings.DHC.Plants.Cooling.BaseClasses.ReversibleConnection revCon(redeclare final package Medium = Medium, final m_flow_nominal=m_flow_nominal, final mTan_flow_nominal=mTan_flow_nominal, final dpPum_nominal=dpPum_nominal, final dpVal_nominal=dpVal_nominal, final T_start=T_CHWS_nominal) "Reversible connection"; Buildings.DHC.Plants.Cooling.Controls.FlowControl floCon( final mChi_flow_nominal=mChi_flow_nominal, final mTan_flow_nominal=mTan_flow_nominal) "Control block for storage plant flows"; Buildings.DHC.Plants.Cooling.Controls.TankStatus tanSta( TLow=T_CHWS_nominal + 0.5, THig=T_CHWR_nominal - 0.5) "Tank status"; Modelica.Blocks.Interfaces.BooleanInput chiEnaSta "Chiller enable status, true if chiller is enabled"; Modelica.Blocks.Interfaces.IntegerInput com "Command: 1 = charge tank, 2 = no command, 3 = discharge from tank"; Modelica.Blocks.Interfaces.BooleanInput hasLoa "Set to true if the district has a load"; Modelica.Blocks.Interfaces.RealInput yPum(final unit="1") "Normalized speed signal for the secondary pump"; Buildings.Fluid.Sensors.RelativePressure senRelPre( redeclare final package Medium = Medium) "Relative pressure sensor"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput dp( final quantity="PressureDifference", final unit="Pa", final displayUnit="Pa") "Pressure drop accross the connection (measured)"; Modelica.Blocks.Interfaces.BooleanOutput isChaRem "Is operated for remote charging"; equation connect(tanSta.y, floCon.tanSta); connect(floCon.mPriPum_flow, pumPri.m_flow_in); connect(floCon.ySecPum,revCon. yPum); connect(floCon.yVal,revCon. yVal); connect(tanBra.TTan,tanSta. TTan); connect(chiEnaSta, floCon.chiEnaSta); connect(com, floCon.com); connect(hasLoa, floCon.hasLoa); connect(yPum, floCon.yPum); connect(port_b2, chi2PreDro.port_b); connect(tanBra.port_a2, port_a2); connect(revCon.port_b, port_b1); connect(port_a1, pumPri.port_a); connect(pumPri.port_b, tanBra.port_a1); connect(tanBra.port_b2, chi2PreDro.port_a); connect(tanBra.port_b1, revCon.port_a); connect(port_b1, senRelPre.port_a); connect(port_a2, senRelPre.port_b); connect(senRelPre.p_rel, dp); connect(floCon.isChaRem, isChaRem); end StoragePlant;