Line_dc

See also

Unit Systems and Conventions
Standard Type Libraries

Create Function

DC lines can be either created from the standard type library (create_line_dc) or with custom values (create_line_dc_from_parameters).

pandapower.create_line_dc(net, from_bus_dc, to_bus_dc, length_km, std_type, name=None, index=None, geodata=None, df=1.0, parallel=1, in_service=True, max_loading_percent=nan, alpha=nan, temperature_degree_celsius=nan, **kwargs)

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

INPUT:

net - The net within this line should be created

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

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

length_km (float) - The line length in km

std_type (string) - Name of a standard linetype :

• Pre-defined in standard_linetypes

or

• Customized std_type made using create_std_type()

OPTIONAL:

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

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 line geodata of the line_dc. 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_dc 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)

alpha (float) - temperature coefficient of resistance: R(T) = R(T_0) * (1 + alpha * (T - T_0)))

temperature_degree_celsius (float) - line temperature for which line resistance is adjusted

tdpf (bool) - whether the line is considered in the TDPF calculation

wind_speed_m_per_s (float) - wind speed at the line in m/s (TDPF)

wind_angle_degree (float) - angle of attack between the wind direction and the line (TDPF)

conductor_outer_diameter_m (float) - outer diameter of the line conductor in m (TDPF)

air_temperature_degree_celsius (float) - ambient temperature in °C (TDPF)

reference_temperature_degree_celsius (float) - reference temperature in °C for which r_ohm_per_km for the line_dc is specified (TDPF)

solar_radiation_w_per_sq_m (float) - solar radiation on horizontal plane in W/m² (TDPF)

solar_absorptivity (float) - Albedo factor for absorptivity of the lines (TDPF)

emissivity (float) - Albedo factor for emissivity of the lines (TDPF)

r_theta_kelvin_per_mw (float) - thermal resistance of the line (TDPF, only for simplified method)

mc_joule_per_m_k (float) - specific mass of the conductor multiplied by the specific thermal capacity of the material (TDPF, only for thermal inertia consideration with tdpf_delay_s parameter)

OUTPUT:

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

EXAMPLE:

create_line_dc(net, from_bus_dc = 0, to_bus_dc = 1, length_km=0.1, std_type=”NAYY 4x50 SE”, name = “line_dc1”)

pandapower.create_line_dc_from_parameters(net, from_bus_dc, to_bus_dc, length_km, r_ohm_per_km, max_i_ka, name=None, index=None, type=None, geodata=None, in_service=True, df=1.0, parallel=1, max_loading_percent=nan, alpha=nan, temperature_degree_celsius=nan, g_us_per_km=0.0, **kwargs)

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

INPUT:

net - The net within this dc line should be created

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

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

length_km (float) - The dc line length in km

r_ohm_per_km (float) - dc line resistance in ohm 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 dc line (“ol” for overhead dc line or “cs” for cable system)

df (float, 1) - derating factor: maximal current of dc 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

g0_us_per_km (float, 0) - zero sequence 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 dc line. The first row should be the coordinates of dc bus a and the last should be the coordinates of dc 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)

alpha (float) - temperature coefficient of resistance: R(T) = R(T_0) * (1 + alpha * (T - T_0)))

temperature_degree_celsius (float) - line temperature for which line resistance is adjusted

tdpf (bool) - whether the line is considered in the TDPF calculation

wind_speed_m_per_s (float) - wind speed at the line in m/s (TDPF)

wind_angle_degree (float) - angle of attack between the wind direction and the line (TDPF)

conductor_outer_diameter_m (float) - outer diameter of the line conductor in m (TDPF)

air_temperature_degree_celsius (float) - ambient temperature in °C (TDPF)

reference_temperature_degree_celsius (float) - reference temperature in °C for which r_ohm_per_km for the line is specified (TDPF)

solar_radiation_w_per_sq_m (float) - solar radiation on horizontal plane in W/m² (TDPF)

solar_absorptivity (float) - Albedo factor for absorptivity of the lines (TDPF)

emissivity (float) - Albedo factor for emissivity of the lines (TDPF)

r_theta_kelvin_per_mw (float) - thermal resistance of the line (TDPF, only for simplified method)

mc_joule_per_m_k (float) - specific mass of the conductor multiplied by the specific thermal capacity of the material (TDPF, only for thermal inertia consideration with tdpf_delay_s parameter)

OUTPUT:

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

EXAMPLE:

create_line_dc_from_parameters(net, from_bus_dc = 0, to_bus_dc = 1, lenght_km=0.1, r_ohm_per_km = .01, max_i_ka = 0.4, name = “line_dc1”)

Input Parameters

net.line_dc

Parameter	Datatype	Value Range	Explanation
name	string		name of the dc line
std_type	string		standard type which can be used to easily define dc line parameters with the pandapower standard type library
from_bus_dc*	integer		Index of dc bus where the dc line starts
to_bus_dc*	integer		Index of dc bus where the dc 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]
g_us_per_km*	float	\(\geq\) 0	dielectric conductance of the dc line [micro Siemens per km]
max_i_ka*	float	\(>\) 0	maximal thermal current [kilo Ampere]
parallel*	integer	\(\geq\) 1	number of parallel dc line systems
df*	float	0…1	derating factor (scaling) for max_i_ka
type;string;”| Naming conventions:
“”ol”” - overhead dc line
“”cs”” - underground cable system”;type of dc line
max_loading_percent	float	\(>\) 0	Maximum loading of the dc line
in_service*	boolean	True / False	specifies if the dc line is in service.

*necessary for executing a balanced power flow calculation

Note

Defining a dc line with length zero leads to a division by zero in the power flow and is therefore not allowed. DC 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 dc buses, please use the switch_dc element instead of a dc line with a small impedance!

net.line_dc_geodata

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

Electric Model

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

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

\begin{align*} \{R} &= (r\_ohm\_per\_km) \cdot \frac{length\_km}{parallel} \\ \{G} &= g\_us\_per\_km \cdot 10^-6 \cdot length\_km \cdot parallel\\ \end{align*}

The parameters are then transformed in the per unit system:

\begin{align*} R_N &= \frac{V_N^2}{S_N} \\ r &= \frac{R}{R_N} \\ g &= G \cdot R_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_dc

Parameter	Datatype	Explanation
p_from_mw;float;”active power flow into the dc line at “”from”” dc bus [MW]”
p_to_mw;float;”active power flow into the dc line at “”to”” dc bus [MW]”
pl_mw	float	active power losses of the dc line [MW]
i_from_ka	float	Current at from dc bus [kA]
i_to_ka	float	Current at to dc bus [kA]
i_ka	float	Maximum of i_from_ka and i_to_ka [kA]
vm_from_pu	float	voltage magnitude at from dc bus
vm_to_pu	float	voltage magnitude at to dc bus
loading_percent	float	line loading [%]

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

\begin{align*} p\_from\_mw &= v_{from} \cdot i_{from} \\ p\_to\_mw &= v_{to} \cdot i_{to} \\ pl\_mw &= p\_from\_mw + p\_to\_mw \\ 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*}