Basic Analysis of Contribution from Inverter-Interfaced Generation to Short Circuits in the Synchronous Grid

This article shows a basic analysis of contribution from Inverter-Interfaced Generation (IIG) to short circuits in the Synchronous Grid (SG). A brief description of IIG control is shown, prior to present some relatively realistic waveshapes of IIG voltages and currents during asymmetric faults in the SG. These waveshapes, taken from the literature, are analyzed in detail and taken as reference. Although one conclusion is that they cannot be obtained from the published descriptions of IIG controls, some simulations were performed. In case of double line-to-ground faults, the results from simulations can be similar, in some extent, to the reference waveshapes because the zero-sequence currents are strongly predominant and they only depend on grounding paths. That is, any value of positive- and negative-sequence currents from the IIG could seem to be relatively good if they are insignificant regarding the zero-sequence current. However, there is no zero-sequence current in case of line-to-line faults, and the IIG currents decrease in the waveshapes taken as reference; this result cannot be obtained from simulations, using the published descriptions of IIG controls, and this fact clearly implies incompatibility between both results. The shown results are useful to highlight the need of having better descriptions of IIG controls since the available ones are not useful to obtain a realistic IIG behavior.