A fast fault current calculation method for distribution networks connected with inverter interfaced distributed generators

The integration of the inverter interfaced distributed generation (IIDG) challenges the conventional fault current calculation methods. The existing fault current calculation methods for distribution networks with IIDG connection generally use nodal admittance matrix and its implicit inverse, which take a longer calculation time and are not suitable for electrical engineering. To simplify the calculation process and reduce the calculation time, a new method was proposed. The new method can estimate fault currents of the feeders with IIDG connection with a higher computation speed, using fault current values obtained in networks without IIDG connection as the initial values in the procedure. The proposed method can obtain results without modifying the node impedance matrix and the calculation time was not affected by the nodes number, which can be used for fast short-circuit current calculation in radial distribution networks with IIDG connection. The new method can be conveniently integrated into software packages for power system analysis and relay protection evaluation. • The proposed method can estimate fault currents of the feeders with IIDG connection with a higher computation speed, which is beneficial for electrical engineering. • The new method has advantages in calculation time and accuracy of the results in comparison with the conventional bus-oriented methods. • The method proposed in this paper can be conveniently integrated into software packages for power system analysis and relay protection evaluation.