Inverter Based Resource Fault Response and Short-Circuit Modeling

Renewables which are interfaced to the grid through power electronics (thus referred to as inverter-based resources – IBRs) have different fault response characteristics compared to synchronous generators (SG). The fault current of a SG is of high amplitude, uncontrolled, pre-dominantly defined by the electrical parameters of the SG and the impedance of short-circuit path; by contrast, the fault current of an IBR typically has a low amplitude and is controlled through fast switching of power electronics devices dependent upon manufacturer specific and often proprietary IBR control schemes. In state-of-the-art fault analysis methods and tools a SG is modeled with a voltage source behind an impedance linear model. This model is not applicable for an IBR, and recent developments have resulted in an industry accepted short-circuit modeling approach which represents IBR with a non-linear voltage controlled current source hat captures the impact of inverter controls on the IBR fault response.