ip.rst

Peak Short-Circuit Current

Current Calculation

The peak short-circuit current is calculated as:

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

where κ is the peak factor.

Peak Factor κ

In radial networks, κ is given as:

κ = 1.02 + 0.98e^− 3R/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 κ:

• 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 κ 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, κ is given as:

κ = [1.02 + 0.98e^− 3R/X] ⋅ 1.15

while being limited with κ_min < κ < κ_max depending on the voltage level:

+-------------+--------+--------+ κ_min | κ_max | +=============+========+========+ | < 1 kV | | 1.8 | +-------------+ 1.0 +--------+ | > 1 kV | | 2.0 | +-------------+--------+--------+