Disclosed herein are a variety of systems and methods for estimating a source impedance value. One embodiment may include an intelligent electronic device (IED) configured to interface with an electric power distribution system. The IED may include a communications interface, a processor, and a non-transitory computer-readable storage medium. The computer-readable storage medium may include software instructions executable on the processor that enable the IED to identify a source impedance modeling event at a node in the power distribution system. The software instructions may further enable the IED to receive a plurality of measurements representing an electrical condition at the node prior to the source impedance modeling event and subsequent to the source impedance modeling event. The IED may calculate a source impedance value based on the first plurality of measurements at the node. Based on the source impedance value, a control action may be generated.