Modeling of steady state fault current contribution of inverter-connected generation in PSSe

This paper presents a method to model steady state fault current contribution of inverter-connected generation such as type 4 wind and PV generators or battery energy storage systems (BESS) in commercially available software packages like PSSe during three-phase short-circuits. Inverter-connected generation is typically modelled as a negative load or as a generator in these packages. Both representation fail to reflect the current limiting functionality of inverters. The proposed method is based on the Norton equivalent of the generators. The method consists in adding a resonant admittance to cancel out the impact of the equivalent admittance for fault current computation. This way, iterative computations are avoided and no readjustments are needed for different fault locations. The main advantage is that the proposed method is extremely simple to implement. It has been successfully applied to a simple test system, a PV plant, and one of the isolated power systems of the Canary Islands.