How long does a symmetrical short-circuit current last?

To see the exact value for each selected SMA inverter, refer to the table hereafter Short-Circuit Current Contributions of Individual SMA Inverters. p the characteristic curve of the current. It thus provides much less energy than a conventional generator. The initial symmetrical short-circuit current Ik’’ will not last longer than 50 ms.

Do grid-forming inverters have a short-circuit behavior?

This contribution presents experimental results on the short-circuit behavior of two grid-forming inverters, one commercial prototype and one experimental device. Two different operation modes, grid-connected and islanded, have been investigated and the different requirements are discussed along the results.

Why are short-circuit currents important?

Such currents are relevant for the correct dimensioning of the wiring and the protective devices, both at the system level and the grid level. Grid operators frequently ask manufacturers of PV and battery inverters to provide maximum values of short-circuit currents.

How does a voltage dip affect a short-circuit current contribution?

The short-circuit current contribution during a voltage dip depends largely on the operation mode of the inverter. The following operation modes can occur and influence the uninterrupted short-circuit current Ik. Note that both operating modes are equally available for riding through overvoltage events (high-voltage ride-through, HVRT).

What should a grid operator ask a battery inverter to provide?

Grid operators frequently ask manufacturers of PV and battery inverters to provide maximum values of short-circuit currents. In other cases, the manufacturers are asked to provide characteristic values such as I electrical values at defined times during a grid failure.

Can adapted control schemes reduce fault currents of grid-forming inverters?

Adapted control schemes have been developed to reduce fault currents of grid-forming inverters. This contribution presents experimental results on the short-circuit behavior of two grid-forming inverters, one commercial prototype and one experimental device.