The effect of load current on a three-phase fault

The most short-circuit studies ignore load current since the magnitude of fault current is extremely greater than that of load current. However, as variable and intermittently dispatchable energy resources such as photovoltaic systems, wind farms, and non-linear power electronics based generators have been deployed to distribution networks, they may increase load current. That is, load current that flows from them can affect a magnitude of fault current. Thus, the objective of this paper is to analyze the effect of load current that flows from a distributed energy resource on three-phase fault current. For this purpose, this study develops an algorithm that adds an electric load to positive-, negative-, and zero-sequence impedance matrices in the format of equivalent impedance and calculates three-phase fault current. To verify the algorithm developed in MATLAB, a distribution network system with a distributed energy resource and a load is presented. Then, this study (1) generates a three-phase fault on the system, (2) changes the capacity of an electric load and a distributed energy resource and the location of an electric fault, and finally (3) examines the effect of load and distributed generation with varying capacities on a three-phase fault.