Short-circuit modeling of inverter based distributed generators considering the FRT requirements

In this paper short-circuit models for inverter based distributed generators (IBDGs) are proposed, based on the fault ride through (FRT) requirements of existing distribution codes. Currently, the IBDGs do not have generally accepted short-circuit models as the traditional synchronous and induction generators do. However, as their usage in the power industry is constantly increasing, there is an urgent need for developing the strictly defined short-circuit models for the IBDGs. In this paper, first FRT requirements of several distribution codes are presented and their mutual characteristics are derived. Then, based on these requirements, the IBDG models suitable for real-time short-circuit calculations are proposed. To validate the proposed models, they were integrated in the recently developed real-time short-circuit calculation procedure for active distribution systems. The IEEE 13 test feeder and several large-scale distribution systems consisted of as many as 5200 three-phase busses and 50 IBDGs were used as the cases studies. The simulation results showed that the proposed models provide desirable results for short-circuit calculations in active distribution systems in which the FRT requirements are strictly imposed.