Peak Short-Circuit Current

Current Calculation

The peak short-circuit current is calculated as:

\[\begin{split}\begin{bmatrix} i_{p, 1} \\ \vdots \\ i_{p, n} \\ \end{bmatrix} = \sqrt{2} \left( \begin{bmatrix} \kappa_{1} \\ \vdots \\ \kappa_{1} \\ \end{bmatrix} \begin{bmatrix} \underline{I}''_{kI, 1} \\ \vdots \\ \underline{I}''_{kI, n} \\ \end{bmatrix} + \begin{bmatrix} \underline{I}''_{kII, 1} \\ \vdots \\ \underline{I}''_{kII, n} \\ \end{bmatrix} \right)\end{split}\]

where \(\kappa\) is the peak factor.

Peak Factor \(\kappa\)

In radial networks, \(\kappa\) is given as:

\[\kappa = 1.02 + 0.98 e^{-\frac{3}{R/X}}\]

where \(R/X\) is the R/X ratio of the equivalent short-circuit impedance \(Z_k\) at the fault location.

In meshed networks, the standard defines three possibilities for the calculation of \(\kappa\):

  • Method A: Uniform Ratio R/X
  • Method B: R/X ratio at short-circuit location
  • Method C: Equivalent frequency

The user can chose between Methods B and C when running a short circuit calculation. Method C yields the most accurate results according to the standard and is therefore the default option. Method A is only suited for estimated manual calculations with low accuracy and therefore not implemented in pandapower.

Method C: Equivalent frequency

For method C, the same formula for \(\kappa\) is used as for radial grids. The R/X value that is inserter is however not the

Method B: R/X Ratio at short-circuit location

For method B, \(\kappa\) is given as:

\[\kappa = [1.02 + 0.98 e^{-\frac{3}{R/X}}] \cdot 1.15\]

while being limited with \(\kappa_{min} < \kappa < \kappa_{max}\) depending on the voltage level:

Voltage Level \(\kappa_{min}\) \(\kappa_{max}\)
< 1 kV 1.0 1.8
> 1 kV 2.0