============= Impedance =============
.. seealso::
:ref:`Unit Systems and Conventions <conventions>`
.. autofunction:: pandapower.create_impedance
net.impedance
.. tabularcolumns:: |p{0.10\linewidth}|p{0.10\linewidth}|p{0.15\linewidth}|p{0.4\linewidth}|
*necessary for executing a power flow calculation.
The impedance is modelled as a longitudinal per unit impedance with \underline{z}_{ft} \neq \underline{z}_{tf} :
The per unit values given in the parameter table are assumed to be relative to the rated voltage of from and to bus as well as to the apparent power given in the table. The per unit values are therefore transformed into the network per unit system:
\begin{align*}
\underline{z}_{ft} &= (rft\_pu + j \cdot xft\_pu) \cdot \frac{S_{N}}{sn\_kva} \\
\underline{z}_{tf} &= (rft\_pu + j \cdot xtf\_pu) \cdot \frac{S_{N}}{sn\_kva} \\
\end{align*}
where S_{N} is the reference power of the per unit system (see :ref:`Unit Systems and Conventions<conventions>`).
The asymetric impedance results in an asymetric nodal point admittance matrix:
\begin{bmatrix} Y_{00} & \dots & \dots & Y_{nn} \\
\vdots & \ddots & \underline{y}_{ft} & \vdots \\
\vdots & \underline{y}_{tf} & \ddots & \vdots \\
\underline{Y}_{n0} & \dots & \dots & \underline{y}_{nn}\\
\end{bmatrix}
net.res_impedance
.. tabularcolumns:: |p{0.10\linewidth}|p{0.1\linewidth}|p{0.55\linewidth}|
\begin{align*}
i\_from\_ka &= i_{from}\\
i\_to\_ka &= i_{to}\\
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 \\
\end{align*}