Abstract
This paper presents a method to identify power system impedance in real-time, using signals obtained from grid connected power electronic converters. The method uses wavelets to analyse the transients associated with a small disturbance imposed by the power converter, and determine the net impedance back to source. A data capture period of 5ms only is required for accurate impedance estimation, providing the possibility of ultra fast fault detection (i.e. with one half cycle). The paper describes how the method may be used to enhance operation during faults for distributed generation. This impedance estimation has potential application in renewable/distributed energy systems, STATCOM, and proposed solid state substations.