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).

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*}