Line¶

Create Function¶

Lines can be either created from the standard type library (create_line) or with custom values (create_line_from_parameters).

pandapower.create_line(net, from_bus, to_bus, length_km, std_type, name=None, index=None, geodata=None, df=1., parallel=1, in_service=True, max_loading_percent=nan)¶

Creates a line element in net[“line”] The line parameters are defined through the standard type library.

INPUT:

net - The net within this line should be created

from_bus (int) - ID of the bus on one side which the line will be connected with

to_bus (int) - ID of the bus on the other side which the line will be connected with

length_km (float) - The line length in km

std_type (string) - The linetype of a standard line pre-defined in standard_linetypes.

OPTIONAL:

name (string, None) - A custom name for this line

index (int, None) - Force a specified ID if it is available. If None, the index one higher than the highest already existing index is selected.

geodata (array, default None, shape= (,2L)) - The linegeodata of the line. The first row should be the coordinates of bus a and the last should be the coordinates of bus b. The points in the middle represent the bending points of the line

in_service (boolean, True) - True for in_service or False for out of service

df (float, 1) - derating factor: maximal current of line in relation to nominal current of line (from 0 to 1)

parallel (integer, 1) - number of parallel line systems

max_loading_percent (float) - maximum current loading (only needed for OPF)

OUTPUT:

index (int) - The unique ID of the created line

EXAMPLE:

create_line(net, “line1”, from_bus = 0, to_bus = 1, length_km=0.1, std_type=”NAYY 4x50 SE”)

pandapower.create_line_from_parameters(net, from_bus, to_bus, length_km, r_ohm_per_km, x_ohm_per_km, c_nf_per_km, max_i_ka, name=None, index=None, type=None, geodata=None, in_service=True, df=1., parallel=1, g_us_per_km=0., max_loading_percent=nan, **kwargs)¶

Creates a line element in net[“line”] from line parameters.

INPUT:

net - The net within this line should be created

from_bus (int) - ID of the bus on one side which the line will be connected with

to_bus (int) - ID of the bus on the other side which the line will be connected with

length_km (float) - The line length in km

r_ohm_per_km (float) - line resistance in ohm per km

x_ohm_per_km (float) - line reactance in ohm per km

c_nf_per_km (float) - line capacitance in nano Farad per km

max_i_ka (float) - maximum thermal current in kilo Ampere

OPTIONAL:

name (string, None) - A custom name for this line

index (int, None) - Force a specified ID if it is available. If None, the index one higher than the highest already existing index is selected.

in_service (boolean, True) - True for in_service or False for out of service

type (str, None) - type of line (“ol” for overhead line or “cs” for cable system)

df (float, 1) - derating factor: maximal current of line in relation to nominal current of line (from 0 to 1)

g_us_per_km (float, 0) - dielectric conductance in micro Siemens per km

parallel (integer, 1) - number of parallel line systems

geodata (array, default None, shape= (,2L)) - The linegeodata of the line. The first row should be the coordinates of bus a and the last should be the coordinates of bus b. The points in the middle represent the bending points of the line

max_loading_percent (float) - maximum current loading (only needed for OPF)

OUTPUT:

index (int) - The unique ID of the created line

EXAMPLE:

create_line_from_parameters(net, “line1”, from_bus = 0, to_bus = 1, lenght_km=0.1, r_ohm_per_km = .01, x_ohm_per_km = 0.05, c_nf_per_km = 10, max_i_ka = 0.4)

Input Parameters¶

net.line

Parameter	Datatype	Value Range	Explanation
name	string		name of the line
std_type	string		standard type which can be used to easily define line parameters with the pandapower standard type library
from_bus*	integer		Index of bus where the line starts
to_bus*	integer		Index of bus where the line ends
length_km*	float	\(>\) 0	length of the line [km]
r_ohm_per_km*	float	\(\geq\) 0	resistance of the line [Ohm per km]
x_ohm_per_km*	float	\(\geq\) 0	inductance of the line [Ohm per km]
c_nf_per_km*	float	\(\geq\) 0	capacitance of the line [nano Farad per km]
g_us_per_km*	float	\(\geq\) 0	dielectric conductance of the line [micro Siemens per km]
max_i_ka*	float	\(>\) 0	maximal thermal current [kilo Ampere]
parallel*	integer	\(\geq\) 1	number of parallel line systems
df*	float	0…1	derating factor (scaling) for max_i_ka
type	string	Naming conventions: “ol” - overhead line “cs” - underground cable system	type of line
max_loading_percent**	float	\(>\) 0	Maximum loading of the line
endtemp_degree***	float	\(>\) 0	Short-Circuit end temperature of the line
in_service*	boolean	True / False	specifies if the line is in service.

*necessary for executing a power flow calculation
**optimal power flow parameter
***short-circuit calculation parameter

Note

Defining a line with length zero leads to a division by zero in the power flow and is therefore not allowed. Lines with a very low impedance might lead to convergence problems in the power flow for the same reason. If you want to directly connect two buses, please use the switch element instead of a line with a small impedance!

net.line_geodata

Parameter	Datatype	Explanation
coords	list	List of (x,y) tuples that mark the inflexion points of the line

Electric Model¶

Lines are modelled with the \(\pi\)-equivalent circuit:

The elements in the equivalent circuit are calculated from the parameters in the net.line dataframe as:

\begin{align*} \underline{Z} &= (r\_ohm\_per\_km + j \cdot x\_ohm\_per\_km) \cdot \frac{length\_km}{parallel} \\ \underline{Y}&= (g\_us\_per\_km \cdot 1 \cdot 10^-6 + j \cdot 2 \pi f \cdot c\_nf\_per\_km \cdot 1 \cdot 10^-9) \cdot length\_km \cdot parallel \end{align*}

The power system frequency \(f\) is defined when creating an empty network, the default value is \(f = 50 Hz\).

The parameters are then transformed in the per unit system:

\begin{align*} Z_{N} &= \frac{V_{N}^2}{S_{N}} \\ \underline{z} &= \frac{\underline{Z}}{Z_{N}} \\ \underline{y} &= \underline{Y} \cdot Z_{N} \\ \end{align*}

Where the reference voltage \(V_{N}\) is the nominal voltage at the from bus and the rated apparent power \(S_{N}\) is defined system wide in the net object (see Unit Systems and Conventions).

Note

pandapower assumes that nominal voltage of from bus and to bus are equal, which means pandapower does not support lines that connect different voltage levels. If you want to connect different voltage levels, either use a transformer or an impedance element.

Result Parameters¶

net.res_line

Parameter	Datatype	Explanation
p_from_kw	float	active power flow into the line at “from” bus [kW]
q_from_kvar	float	reactive power flow into the line at “from” bus [kVar]
p_to_kw	float	active power flow into the line at “to” bus [kW]
q_to_kvar	float	reactive power flow into the line at “to” bus [kVar]
pl_kw	float	active power losses of the line [kW]
ql_kvar	float	reactive power consumption of the line [kVar]
i_from_ka	float	Current at to bus [kA]
i_to_ka	float	Current at from bus [kA]
i_ka	float	Maximum of i_from_ka and i_to_ka [kA]
loading_percent	float	line loading [%]

The power flow results in the net.res_line table are defined as:

\begin{align*} p\_from\_kw &= Re(\underline{v}_{from} \cdot \underline{i}^*_{from}) \\ q\_from\_kvar &= Im(\underline{v}_{from} \cdot \underline{i}^*_{from}) \\ p\_to\_kw &= Re(\underline{v}_{to} \cdot \underline{i}^*_{to}) \\ q\_to\_kvar &= Im(\underline{v}_{to} \cdot \underline{i}^*_{to}) \\ pl\_kw &= p\_from\_kw + p\_to\_kw \\ ql\_kvar &= q\_from\_kvar + q\_to\_kvar \\ i\_from\_ka &= i_{from} \\ i\_to\_ka &= i_{to} \\ i\_ka &= max(i_{from}, i_{to}) \\ loading\_percent &= \frac{i\_ka}{imax\_ka \cdot df \cdot parallel} \cdot 100 \end{align*}

net.res_line_est

The state estimation results are put into net.res_line_est with the same definition as in net.res_line.

Parameter	Datatype	Explanation
p_from_kw	float	active power flow into the line at “from” bus [kW]
q_from_kvar	float	reactive power flow into the line at “from” bus [kVar]
p_to_kw	float	active power flow into the line at “to” bus [kW]
q_to_kvar	float	reactive power flow into the line at “to” bus [kVar]
pl_kw	float	active power losses of the line [kW]
ql_kvar	float	reactive power consumption of the line [kVar]
i_from_ka	float	Current at to bus [kA]
i_to_ka	float	Current at from bus [kA]
i_ka	float	Maximum of i_from_ka and i_to_ka [kA]
loading_percent	float	line loading [%]