Buildings.Electrical.Transmission.Functions
Package that contains functions to compute cable properties
Information
This package contains various functions that are used to compute cable properties and select the default cable during automatic parametrization.
Extends from Modelica.Icons.Package (Icon for standard packages).
Package Content
| Name | Description |
|---|---|
 R_AC_correction
|
This function computes the correction factor of the DC resistance for AC systems at 60 Hz |
| computeGMD
|
This function computes the geometric mean distance of a three-phase transmission line |
| computeGMR
|
This function computes the geometric mean radius of a cable with 1 to 4 conductors |
| selectCable_low
|
This function is used to automatically select the type of cable for low voltages |
| selectCable_med
|
This function is used to automatically select the type of cable for medium voltages |
| selectVoltageLevel
|
This function computes the voltage level (low, medium or high) given the nominal voltage |
 Validation
|
Buildings.Electrical.Transmission.Functions.R_AC_correction
This function computes the correction factor of the DC resistance for AC systems at 60 Hz
Information
This function computes a correction factor for adapting the DC resistance when working with AC voltages. The correction factor assumes f = 60 Hz.
The correction is based on the type of cabel (AWG or kcmil) and the material.
| Type (AWG or kcmil) | Material | Correction factor |
|---|---|---|
| 1/0 | Aluminium | 1.0 |
| 2/0 | Aluminium | 1.001 |
| 3/0 | Aluminium | 1.001 |
| 4/0 | Aluminium | 1.001 |
| 250 | Aluminium | 1.002 |
| 300 | Aluminium | 1.003 |
| 350 | Aluminium | 1.004 |
| 400 | Aluminium | 1.005 |
| 500 | Aluminium | 1.007 |
| 600 | Aluminium | 1.010 |
| 700 | Aluminium | 1.013 |
| 750 | Aluminium | 1.015 |
| 800 | Aluminium | 1.017 |
| 1000 | Aluminium | 1.026 |
| 1250 | Aluminium | 1.040 |
| 1500 | Aluminium | 1.058 |
| 1750 | Aluminium | 1.079 |
| 2000 | Aluminium | 1.100 |
| 2500 | Aluminium | 1.142 |
| Type (AWG or kcmil) | Material | Correction factor |
|---|---|---|
| 1/0 | Copper | 1.0 |
| 2/0 | Copper | 1.001 |
| 3/0 | Copper | 1.002 |
| 4/0 | Copper | 1.004 |
| 250 | Copper | 1.005 |
| 300 | Copper | 1.006 |
| 350 | Copper | 1.009 |
| 400 | Copper | 1.011 |
| 500 | Copper | 1.018 |
| 600 | Copper | 1.025 |
| 700 | Copper | 1.034 |
| 750 | Copper | 1.039 |
| 800 | Copper | 1.044 |
| 1000 | Copper | 1.067 |
| 1250 | Copper | 1.102 |
| 1500 | Copper | 1.142 |
| 1750 | Copper | 1.185 |
| 2000 | Copper | 1.233 |
| 2500 | Copper | 1.326 |
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| String | size | Size of the commercial cable (AWG or kcmil) | |
| Material | material | Material of the cable |
Outputs
| Type | Name | Description |
|---|---|---|
| Real | correction | Correction factor |
Modelica definition
function R_AC_correction
"This function computes the correction factor of the DC resistance for AC systems at 60 Hz"
input String size "Size of the commercial cable (AWG or kcmil)";
input Buildings.Electrical.Transmission.Types.Material material
"Material of the cable";
output Real correction "Correction factor";
algorithm
if material == Buildings.Electrical.Transmission.Types.Material.Al then
if size == "1/0" then
correction := 1.0;
elseif size == "2/0" then
correction := 1.001;
elseif size == "3/0" then
correction := 1.001;
elseif size == "4/0" then
correction := 1.001;
elseif size == "250" then
correction := 1.002;
elseif size == "300" then
correction := 1.003;
elseif size == "350" then
correction := 1.004;
elseif size == "400" then
correction := 1.005;
elseif size == "500" then
correction := 1.007;
elseif size == "600" then
correction := 1.01;
elseif size == "700" then
correction := 1.013;
elseif size == "750" then
correction := 1.015;
elseif size == "800" then
correction := 1.017;
elseif size == "1000" then
correction := 1.026;
elseif size == "1250" then
correction := 1.04;
elseif size == "1500" then
correction := 1.058;
elseif size == "1750" then
correction := 1.079;
elseif size == "2000" then
correction := 1.1;
elseif size == "2500" then
correction := 1.142;
else
correction := 1.0;
end if;
elseif material == Buildings.Electrical.Transmission.Types.Material.Cu then
if size == "1/0" then
correction := 1.0;
elseif size == "2/0" then
correction := 1.001;
elseif size == "3/0" then
correction := 1.002;
elseif size == "4/0" then
correction := 1.004;
elseif size == "250" then
correction := 1.005;
elseif size == "300" then
correction := 1.006;
elseif size == "350" then
correction := 1.009;
elseif size == "400" then
correction := 1.011;
elseif size == "500" then
correction := 1.018;
elseif size == "600" then
correction := 1.025;
elseif size == "700" then
correction := 1.034;
elseif size == "750" then
correction := 1.039;
elseif size == "800" then
correction := 1.044;
elseif size == "1000" then
correction := 1.067;
elseif size == "1250" then
correction := 1.102;
elseif size == "1500" then
correction := 1.142;
elseif size == "1750" then
correction := 1.185;
elseif size == "2000" then
correction := 1.233;
elseif size == "2500" then
correction := 1.326;
else
correction := 1.0;
end if;
else
assert(material <> Buildings.Electrical.Transmission.Types.Material.Al and
material <> Buildings.Electrical.Transmission.Types.Material.Cu,
"In function Buildings.Electrical.Transmission.Functions.R_AC_Correction,
does not support material " + String(material) + ".
The selected cable has the R_AC_Correction of the Copper.",
level = AssertionLevel.warning);
correction := 1.0;
end if;
end R_AC_correction;
Buildings.Electrical.Transmission.Functions.computeGMD
This function computes the geometric mean distance of a three-phase transmission line
Information
This function computes the Geometric Mean Distance of a cable.
The GMD is computed as
GMD = (d1 d2 d3)1/3,
where d1, d2, and d3 are the distances between the conductors.
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Length | d1 | Distance between conductors [m] | |
| Length | d2 | d1 | Distance between conductors [m] |
| Length | d3 | 2*d1 | Distance between conductors [m] |
Outputs
| Type | Name | Description |
|---|---|---|
| Length | GMD | Geometric Mean Distance [m] |
Modelica definition
function computeGMD
"This function computes the geometric mean distance of a three-phase transmission line"
input Modelica.SIunits.Length d1 "Distance between conductors";
input Modelica.SIunits.Length d2 = d1 "Distance between conductors";
input Modelica.SIunits.Length d3 = 2*d1 "Distance between conductors";
output Modelica.SIunits.Length GMD "Geometric Mean Distance";
algorithm
GMD := (d1*d2*d3)^(1.0/3.0);
end computeGMD;
Buildings.Electrical.Transmission.Functions.computeGMR
This function computes the geometric mean radius of a cable with 1 to 4 conductors
Information
This function computes the Geometric Mean Radius (GMR) of a cable.
The GMR is computed as follow, depending on the number of conductors N that are part of the cable, and the diamater of the conductor d.
| Equation | Condition |
|---|---|
| 0.7788 (d/2) | N = 1 |
| d1/2 | N = 2 |
| d2/3 | N = 3 |
| d2/3 | N = 4 |
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Length | d | Diameter of the conductor [m] | |
| Integer | N | 1 | Number of conductors |
Outputs
| Type | Name | Description |
|---|---|---|
| Length | GMR | Geometric Mean Radius [m] |
Modelica definition
function computeGMR
"This function computes the geometric mean radius of a cable with 1 to 4 conductors"
input Modelica.SIunits.Length d "Diameter of the conductor";
input Integer N = 1 "Number of conductors";
output Modelica.SIunits.Length GMR "Geometric Mean Radius";
algorithm
assert(N > 0 and N < 5,
"The number of conductors N must be between 1 and 4, received N=" + String(N) + ".");
if N==1 then
GMR := 0.5*d*0.7788;
elseif N==2 then
GMR := sqrt(d);
elseif N==3 then
GMR := (d^2)^(1/3);
else // N == 4
GMR := 1.09*(d^3)^(1/4);
end if;
end computeGMR;
Buildings.Electrical.Transmission.Functions.selectCable_low
This function is used to automatically select the type of cable for low voltages
Information
This function selects the default cable for a low voltage transmission line.
The function takes as inputs the nominal voltage Vnominal and the nominal power Pnominal. It computes the maximum current current that can flow through the cable as
IMAX = SF Pnominal / Vnominal,
where SF is the safety factor. By default the safety factor is equal to 1.2.
Using IMAX, the function selects the smallest cable that has an ampacity higher than IMAX. The cables are selected from Buildings.Electrical.Transmission.LowVoltageCables.
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Power | P_nominal | 0 | Rated power [W] |
| Voltage | V_nominal | 0 | Rated voltage [V] |
Outputs
| Type | Name | Description |
|---|---|---|
| Generic | cable | Cable |
Modelica definition
function selectCable_low "This function is used to automatically select the
type of cable for low voltages"
input Modelica.SIunits.Power P_nominal = 0 "Rated power";
input Modelica.SIunits.Voltage V_nominal = 0 "Rated voltage";
output Buildings.Electrical.Transmission.LowVoltageCables.Generic cable "Cable";
protected
parameter Real safety_factor = 1.2;
Modelica.SIunits.Current I_nominal "Nominal current flowing through the line";
Buildings.Electrical.Transmission.LowVoltageCables.Cu10 cu10;
Buildings.Electrical.Transmission.LowVoltageCables.Cu20 cu20;
Buildings.Electrical.Transmission.LowVoltageCables.Cu25 cu25;
Buildings.Electrical.Transmission.LowVoltageCables.Cu35 cu35;
Buildings.Electrical.Transmission.LowVoltageCables.Cu50 cu50;
Buildings.Electrical.Transmission.LowVoltageCables.Cu95 cu95;
Buildings.Electrical.Transmission.LowVoltageCables.Cu100 cu100;
algorithm
assert(Transmission.Functions.selectVoltageLevel(V_nominal) == Buildings.Electrical.Types.VoltageLevel.Low,
"In function Buildings.Electrical.Transmission.Functions.selectCable_low,
cable autosizing has a nominal Voltage " + String(V_nominal) + " [V].
The low voltage cables do not support such a voltage level.",
level=AssertionLevel.error);
// Check if it's possible to compute the current
if V_nominal > 0 then
I_nominal :=safety_factor*P_nominal/V_nominal;
else
I_nominal :=0;
end if;
// Assumed the material is Copper
if I_nominal < cu10.Amp then
cable := cu10;
elseif I_nominal >= cu10.Amp and I_nominal < cu20.Amp then
cable := cu20;
elseif I_nominal >= cu20.Amp and I_nominal < cu25.Amp then
cable := cu25;
elseif I_nominal >= cu25.Amp and I_nominal < cu35.Amp then
cable := cu35;
elseif I_nominal >= cu35.Amp and I_nominal < cu50.Amp then
cable := cu50;
elseif I_nominal >= cu50.Amp and I_nominal < cu95.Amp then
cable := cu95;
elseif I_nominal >= cu95.Amp and I_nominal < cu100.Amp then
cable := cu100;
else
assert(I_nominal < cu100.Amp,
"In function Buildings.Electrical.Transmission.Functions.selectCable_low,
cable autosizing does not support a current of " + String(I_nominal) + " [A].
The selected cable will be undersized.",
level=AssertionLevel.warning);
cable := cu100;
end if;
end selectCable_low;
Buildings.Electrical.Transmission.Functions.selectCable_med
This function is used to automatically select the type of cable for medium voltages
Information
This function selects the default cable for a medium voltage transmission line.
The function takes as inputs the nominal voltage Vnominal and the nominal power Pnominal. It computes the maximum current current that can flow through the cable as
IMAX = SF Pnominal / Vnominal,
where SF is the safety factor. By default the safety factor is equal to 1.2.
Using IMAX, the function selects the smallest cable that has an ampacity higher than IMAX. The cables are selected from Buildings.Electrical.Transmission.MediumVoltageCables.
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Power | P_nominal | 0 | Rated power [W] |
| Voltage | V_nominal | 0 | Rated voltage [V] |
Outputs
| Type | Name | Description |
|---|---|---|
| Generic | cable | Cable |
Modelica definition
function selectCable_med "This function is used to automatically select the
type of cable for medium voltages"
input Modelica.SIunits.Power P_nominal = 0 "Rated power";
input Modelica.SIunits.Voltage V_nominal = 0 "Rated voltage";
output Buildings.Electrical.Transmission.MediumVoltageCables.Generic cable "Cable";
protected
parameter Real safety_factor = 1.2;
Modelica.SIunits.Current I_nominal "Nominal current flowing through the line";
Buildings.Electrical.Transmission.MediumVoltageCables.Annealed_Al_10 Al10;
Buildings.Electrical.Transmission.MediumVoltageCables.Annealed_Al_30 Al30;
Buildings.Electrical.Transmission.MediumVoltageCables.Annealed_Al_40 Al40;
Buildings.Electrical.Transmission.MediumVoltageCables.Annealed_Al_350 Al350;
Buildings.Electrical.Transmission.MediumVoltageCables.Annealed_Al_500 Al500;
Buildings.Electrical.Transmission.MediumVoltageCables.Annealed_Al_1000 Al1000;
Buildings.Electrical.Transmission.MediumVoltageCables.Annealed_Al_1500 Al1500;
algorithm
assert(Transmission.Functions.selectVoltageLevel(V_nominal) == Buildings.Electrical.Types.VoltageLevel.Medium,
"In function Buildings.Electrical.Transmission.Functions.selectCable_med,
cable autosizing has a nominal Voltage " + String(V_nominal) + " [V].
The medium voltage cables do not support such a voltage level.",
level=AssertionLevel.error);
// Check if it's possible to compute the current
if V_nominal > 0 then
I_nominal :=safety_factor*P_nominal/V_nominal;
else
I_nominal :=0;
end if;
// Assumed the material is Copper
if I_nominal < Al10.Amp then
cable := Al10;
elseif I_nominal >= Al10.Amp and I_nominal < Al30.Amp then
cable := Al30;
elseif I_nominal >= Al30.Amp and I_nominal < Al40.Amp then
cable := Al40;
elseif I_nominal >= Al40.Amp and I_nominal < Al350.Amp then
cable := Al350;
elseif I_nominal >= Al350.Amp and I_nominal < Al500.Amp then
cable := Al500;
elseif I_nominal >= Al500.Amp and I_nominal < Al1000.Amp then
cable := Al1000;
elseif I_nominal >= Al1000.Amp and I_nominal < Al1500.Amp then
cable := Al1500;
else
assert(I_nominal < Al1500.Amp,
"Warning: In function Buildings.Electrical.Transmission.Functions.selectCable_med,
cable autosizing does not support a current of " + String(I_nominal) + " [A].
The selected cable will be undersized.",
level=AssertionLevel.warning);
cable := Al10;
end if;
end selectCable_med;
Buildings.Electrical.Transmission.Functions.selectVoltageLevel
This function computes the voltage level (low, medium or high) given the nominal voltage
Information
This function computes the voltage level for a given voltage. The computation is as follows:
| Condition | Voltage Level |
|---|---|
| 0 ≤ V < 1 kV | Low voltage |
| 1 kV ≤ V < 50 kV | Medium voltage |
| V ≥ 50 kV | HIgh voltage |
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Voltage | V | Nominal voltage [V] |
Outputs
| Type | Name | Description |
|---|---|---|
| VoltageLevel | level | Type of voltage level |
Modelica definition
function selectVoltageLevel
"This function computes the voltage level (low, medium or high) given the nominal voltage"
input Modelica.SIunits.Voltage V "Nominal voltage";
output Buildings.Electrical.Types.VoltageLevel level "Type of voltage level";
algorithm
if V <= 0 then
assert(V > 0,
"In function Buildings.Electrical.Transmission.Functions.selectVoltageLevel,
does not support a voltage of " + String(V) + " [V].
The selected voltage level will be assumed to be low.",
level = AssertionLevel.warning);
level := Buildings.Electrical.Types.VoltageLevel.Low;
elseif V <= 1000 then
level := Buildings.Electrical.Types.VoltageLevel.Low;
elseif V > 1000 and V <= 50000 then
level := Buildings.Electrical.Types.VoltageLevel.Medium;
else
level := Buildings.Electrical.Types.VoltageLevel.High;
end if;
end selectVoltageLevel;