Line DC
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=get_default_value('line', 'df'), parallel=get_default_value('line', 'parallel'), in_service=get_default_value('line', 'in_service'), 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.
- Parameters:
net (pandapowerNet) – The net within this line should be created
from_bus_dc (int | integer) – ID of the bus_dc on one side which the line will be connected with
to_bus_dc (int | integer) – 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 (str) – Name of a standard line type: - Pre-defined in standard_linetypes - Customized std_type made using create_std_type()
name (str | None) – A custom name for this line_dc
index (int | integer | None) – Force a specified ID if it is available. If None, the index one higher than the highest already existing index is selected.
geodata (Iterable[tuple[float, float]] | None) – 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 (bool) – True for in_service or False for out of service
df (float) – derating factor, maximum current of line_dc in relation to nominal current of line (from 0 to 1)
parallel (int) – 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
- Keyword Arguments:
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)
- Returns:
The ID of the created dc line
- Return type:
int | integer
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=get_default_value('line_dc', 'in_service'), df=get_default_value('line_dc', 'df'), parallel=get_default_value('line_dc', 'parallel'), max_loading_percent=nan, alpha=nan, temperature_degree_celsius=nan, g_us_per_km=get_default_value('line_dc', 'g_us_per_km'), **kwargs)
Creates a dc line element in net[“line_dc”] from dc line parameters.
- Parameters:
net (pandapowerNet) – The net within this dc line should be created
from_bus_dc (int | integer) – ID of the dc bus on one side which the dc line will be connected with
to_bus_dc (int | integer) – 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
name (str | None) – A custom name for this line
index (int | integer | 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 (bool) – True for in_service or False for out of service
type (Literal['ol', 'cs'] | None) – type of dc line (“ol” for overhead dc line or “cs” for cable system)
df (float) – derating factor: maximum current of dc line in relation to nominal current of line (from 0 to 1)
g_us_per_km (float) – dielectric conductance in micro Siemens per km
g0_us_per_km – zero sequence dielectric conductance in micro Siemens per km
parallel (int) – number of parallel line systems
geodata (Iterable[tuple[float, float]] | None) – 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
- Keyword Arguments:
tdpf – whether the line is considered in the TDPF calculation
wind_speed_m_per_s – wind speed at the line in m/s (TDPF)
wind_angle_degree – angle of attack between the wind direction and the line (TDPF)
conductor_outer_diameter_m – outer diameter of the line conductor in m (TDPF)
air_temperature_degree_celsius – ambient temperature in °C (TDPF)
reference_temperature_degree_celsius – reference temperature in °C for which r_ohm_per_km for the line is specified (TDPF)
solar_radiation_w_per_sq_m – solar radiation on horizontal plane in W/m² (TDPF)
solar_absorptivity – Albedo factor for absorptivity of the lines (TDPF)
emissivity – Albedo factor for emissivity of the lines (TDPF)
r_theta_kelvin_per_mw – thermal resistance of the line (TDPF, only for simplified method)
mc_joule_per_m_k – 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)
- Returns:
The ID of the created line
- Return type:
int | integer
Example
>>> create_line_dc_from_parameters( >>> net, from_bus_dc=0, to_bus_dc=1, length_km=0.1, r_ohm_per_km=.01, max_i_ka=0.4, name="line_dc1" >>> )
Table Structure
net.line_dc
Parameter |
Datatype |
Value Range |
Explanation |
nullable |
required |
optimal power flow |
tdpf |
|---|---|---|---|---|---|---|---|
name |
name of the dc line |
✓ |
|||||
std_type |
standard type which can be used to easily define dc line parameters with the pandapower standard type library |
✓ |
|||||
from_bus_dc |
int |
>=0 |
Index of dc bus where the dc line starts |
✓ |
|||
to_bus_dc |
int |
>=0 |
Index of dc bus where the dc line ends |
✓ |
|||
length_km |
float |
>0 |
length of the line [km] |
✓ |
|||
r_ohm_per_km |
float |
>=0 |
resistance of the line [Ohm per km] |
✓ |
|||
g_us_per_km |
float |
>=0 |
dielectric conductance of the dc line [micro Siemens per km] |
✓ |
|||
max_i_ka |
float |
>=0 |
maximal thermal current [kilo Ampere] |
✓ |
|||
parallel |
int |
>=1 |
number of parallel dc line systems |
✓ |
|||
df |
float |
[0, 1] |
derating factor (scaling) for max_i_ka |
✓ |
|||
type |
type of dc line Naming conventions: “”ol”” - overhead dc line, “”cs”” - underground cable system” |
✓ |
|||||
max_loading_percent |
float |
>0 |
Maximum loading of the dc line |
✓ |
✓ |
||
in_service |
bool |
specifies if the dc line is in service. |
✓ |
||||
geo |
geojson.LineString object or its string representation |
✓ |
|||||
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) |
✓ |
✓ |
*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!
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:
The parameters are then transformed in the per unit system:
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 Table
net.res_line_dc
Parameter |
Datatype |
Explanation |
nullable |
required |
|---|---|---|---|---|
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: