Buildings.Electrical.DC.Lines

Package with models for DC electrical lines

Information

This package contains models for lines for DC circuits.

Extends from Modelica.Icons.Package (Icon for standard packages).

Package Content

Name	Description
Line	Model of a DC electrical line
TwoPortRCLine	Model of a two port DC resistance and capacity (T-model)
TwoPortResistance	Model of a two port DC resistance
Examples	Package with example models

Buildings.Electrical.DC.Lines.Line

Model of a DC electrical line

Buildings.Electrical.DC.Lines.Line

Information

This model represents a DC cable. The model is based on Buildings.Electrical.DC.Lines.TwoPortRCLine and provides functionalities to parametrize the values of R and C either using commercial cables or using default values.

Extends from Buildings.Electrical.Transmission.BaseClasses.PartialLine (Partial cable line dispersion model).

Parameters

Type	Name	Default	Description
replaceable package PhaseSystem_p		PartialPhaseSystem	Phase system of terminal p
replaceable package PhaseSystem_n		PartialPhaseSystem	Phase system of terminal n
Length	l		Length of the line [m]
Power	P_nominal		Nominal power of the line [W]
Voltage	V_nominal		Nominal voltage of the line [V]
Model
Assumptions
Boolean	use_C	false	Set to true to add a capacitance in the center of the line
Load	modelMode	Types.Load.FixedZ_steady_state	Select between steady state and dynamic model
Thermal
Boolean	use_T	false	If true, enables the input for the temperature of the cable
Temperature	TCable	T_ref	Fixed temperature of the cable [K]
Tech. specification
Auto/Manual mode
CableMode	mode	Buildings.Electrical.Types.C...	Select if choosing the cable automatically or between a list of commercial options
Manual mode
Generic	commercialCable	Buildings.Electrical.Transmi...	Commercial cables options

Connectors

Type	Name	Description
replaceable package PhaseSystem_p		Phase system of terminal p
replaceable package PhaseSystem_n		Phase system of terminal n
input RealInput	T	Temperature of the cable

Modelica definition

model Line "Model of a DC electrical line" extends Buildings.Electrical.Transmission.BaseClasses.PartialLine( redeclare package PhaseSystem_p = PhaseSystems.TwoConductor, redeclare package PhaseSystem_n = PhaseSystems.TwoConductor, redeclare Interfaces.Terminal_n terminal_n, redeclare Interfaces.Terminal_p terminal_p, final modelMode=Types.Load.FixedZ_steady_state, commercialCable = Buildings.Electrical.Transmission.Functions.selectCable_low(P_nominal, V_nominal)); TwoPortRCLine lineRC( final useHeatPort=true, final R=R, final V_nominal=V_nominal, final T_ref=T_ref, final M=M, final C=C, final use_C=use_C); equation connect(terminal_n, lineRC.terminal_n); connect(lineRC.terminal_p, terminal_p); connect(cableTemp.port, lineRC.heatPort); end Line;

Buildings.Electrical.DC.Lines.TwoPortRCLine

Model of a two port DC resistance and capacity (T-model)

Buildings.Electrical.DC.Lines.TwoPortRCLine

Information

This model represents a series of two resistances and a capacitance that connect two DC interfaces. This model can be used to represent a cable in a DC grid.

The model represents the lumped resistances and capacity (T-model) as shown in the figure below.

As can be seen in the figure, the resistance R is split in two halves and the capacitance is located in the center. The capacitance in the center is optional and can be selected using the boolean flag use_C = true. The model is either dynamic or static depending on the presence of the capacitive effect.

Extends from Buildings.Electrical.Transmission.BaseClasses.PartialTwoPortRLC (Partial model of an RLC element that links two electrical connectors).

Parameters

Type	Name	Default	Description
replaceable package PhaseSystem_p		PartialPhaseSystem	Phase system of terminal p
replaceable package PhaseSystem_n		PartialPhaseSystem	Phase system of terminal n
Boolean	useHeatPort	false	=true, if heatPort is enabled
Temperature	T	T_ref	Fixed device temperature if useHeatPort = false [K]
Resistance	R		Resistance at temperature T_ref [Ohm]
Temperature	T_ref	298.15	Reference temperature [K]
Temperature	M	507.65	Temperature constant (R_actual = R*(M + T_heatPort)/(M + T_ref)) [K]
Capacitance	C		Capacity [F]
Inductance	L	0	Inductance [H]
Voltage	Vc_start	V_nominal	Initial value of the voltage of the capacitance in the middle of the line [V]
Nominal conditions
Voltage	V_nominal		Nominal voltage (V_nominal >= 0) [V]
Model
Assumptions
Boolean	use_C	false	Set to true to add a capacitance in the center of the line

Connectors

Type	Name	Description
replaceable package PhaseSystem_p		Phase system of terminal p
replaceable package PhaseSystem_n		Phase system of terminal n
HeatPort_a	heatPort	Conditional heat port

Modelica definition

model TwoPortRCLine "Model of a two port DC resistance and capacity (T-model)" extends Buildings.Electrical.Transmission.BaseClasses.PartialTwoPortRLC( redeclare package PhaseSystem_p = PhaseSystems.TwoConductor, redeclare package PhaseSystem_n = PhaseSystems.TwoConductor, redeclare Interfaces.Terminal_n terminal_n, redeclare Interfaces.Terminal_p terminal_p, final L=0); parameter Boolean use_C = false "Set to true to add a capacitance in the center of the line"; parameter Modelica.SIunits.Voltage Vc_start = V_nominal "Initial value of the voltage of the capacitance in the middle of the line"; Modelica.SIunits.Voltage Vc(start = Vc_start, stateSelect = StateSelect.prefer) "Voltage of the capacitor"; initial equation if C>0 and use_C then Vc = Vc_start; end if; equation terminal_p.v[1] - (Vc+terminal_p.v[2]) = terminal_p.i[1]*R_actual/2; terminal_n.v[1] - (Vc+terminal_p.v[2]) = terminal_n.i[1]*R_actual/2; if C>0 and use_C then C*der(Vc) = terminal_p.i[1] + terminal_n.i[1]; else Vc = 0.5*(terminal_p.v[1] - terminal_p.v[2] + terminal_n.v[1] - terminal_n.v[2]); end if; terminal_p.v[2] = terminal_n.v[2]; terminal_p.i[2] + terminal_n.i[2] = 0; // Joule losses LossPower = R_actual/2*terminal_p.i[1]^2 + R_actual/2*terminal_n.i[1]^2; end TwoPortRCLine;

Buildings.Electrical.DC.Lines.TwoPortResistance

Model of a two port DC resistance

Buildings.Electrical.DC.Lines.TwoPortResistance

Information

This model represents a resistance that connect two DC interfaces. This model can be used to represent a cable in a DC grid.

The model represents the lumped resistance as shown in the figure below.

Extends from Buildings.Electrical.Transmission.BaseClasses.PartialTwoPortResistance (Partial model of a resistive element that links two electrical connectors).

Parameters

Type	Name	Default	Description
replaceable package PhaseSystem_p		PartialPhaseSystem	Phase system of terminal p
replaceable package PhaseSystem_n		PartialPhaseSystem	Phase system of terminal n
Boolean	useHeatPort	false	=true, if heatPort is enabled
Temperature	T	T_ref	Fixed device temperature if useHeatPort = false [K]
Resistance	R		Resistance at temperature T_ref [Ohm]
Temperature	T_ref	298.15	Reference temperature [K]
Temperature	M	507.65	Temperature constant (R_actual = R*(M + T_heatPort)/(M + T_ref)) [K]

Connectors

Type	Name	Description
replaceable package PhaseSystem_p		Phase system of terminal p
replaceable package PhaseSystem_n		Phase system of terminal n
HeatPort_a	heatPort	Conditional heat port

Modelica definition

model TwoPortResistance "Model of a two port DC resistance" extends Buildings.Electrical.Transmission.BaseClasses.PartialTwoPortResistance ( redeclare package PhaseSystem_p = PhaseSystems.TwoConductor, redeclare package PhaseSystem_n = PhaseSystems.TwoConductor, redeclare Interfaces.Terminal_n terminal_n, redeclare Interfaces.Terminal_p terminal_p); equation // Voltage drop on the resistance lumped on connection between terminals // p.v[1] and n.v[1] terminal_p.v[1] - terminal_n.v[1] = terminal_p.i[1]*R_actual; terminal_p.v[2] = terminal_n.v[2]; // Joule losses LossPower = R_actual*terminal_p.i[1]^2; end TwoPortResistance;