This paper studies the performance of the latest version of the IEC 60909 standard for steady-state fault calculations in power systems including high penetration of renewable energy resources (RESs) utilizing fully-rated converters. The study proposes a simple method to enhance the accuracy of the IEC 60909 in assessment of steady-state fault levels with high penetration of RESs utilizing fully-rated converters. Our improved IEC 60909 method includes the reactive current injection of such resources more precisely according to the grid code, hence results in a better performance of steady-state fault calculations. The simulation results have shown an enhanced accuracy of our methodology compared to the latest version of the IEC 60909. Our findings are confirmed using the IEEE 14-bus test system in DIgSILENT PowerFactory.