A Ground Fault Location Technique for Wound Field Poles of Synchronous Machines Through Frequency Response Analysis

Although frequency response analysis (FRA) is a renowned diagnostic technique in the field of power transformers, it has not gained much traction yet in the domain of rotating electrical machinery. This article presents a novel diagnostics technique that applies FRA to the detection of ground faults in the wound field poles of synchronous machines. To this end, numerous experimental tests were carried out on a testbench comprising a pole of a 40-MVA hydro-generator. The data obtained in the experimental tests was used to build a novel surface fitting-based methodology that estimates the fault position, providing the faulty turn, and that estimates the fault severity, providing the fault resistance. The outputs of the proposed fault location method are valuable to reduce the corrective maintenance times, with the aim of ensuring a proper operation of the power system at the same time that costs are optimized.