Fast short-circuit current calculation of unbalanced distribution networks with inverter-interfaced distributed generators

Abstract

This study proposes an approach for the fast calculation of short-circuit currents in unbalanced distribution networks with inverter-interfaced distributed generators (IIDG). It is capable of estimating the short-circuit current in unbalanced distribution networks with several IIDGs based on the symmetric component without calculating the system bus impedance matrix. Furthermore, the effect of the load on the short-circuit current was considered. Because the IIDG fault characteristic is determined by its fault ride-through control models, the short-circuit current calculation process is formulated as an iterative linear system calculation and can be solved using the simple generalized minimal residual (SGMRES) method. Finally, the analytical results were verified by comparisons with the time-domain simulation results of several test systems in PSCAD.