Algorithm for Fast Detection of Stator Turn Faultsin Variable-Speed Synchronous Generators

Faults between stator winding turns of synchronous generators have led to specific changes in the harmonic content of currents. In this paper, these changes are used to detect faults in variable-speed synchronous generators connected to three-level converters during their operation. Currents typically measured for control purposes are used to avoid installation of additional sensors. The neutral point current of the three-level converter is also evaluated under faults in the generator. Encoder-tuned dynamic filters based on Park transformation and Fourier coefficients together with low-pass filters are used to detect the selected harmonics under variable speeds. The geometric loci of these components are proposed as a method to distinguish between healthy and faulty conditions. Simulation and experimental data are used to test sensitivity, selectivity and detection time of the proposed technique for different fault types. Generalization for a different generator is also presented and tested. Most fault cases were detected using the harmonics.

Automated summary

This paper investigates the changes in harmonic content of currents caused by faults between stator winding turns in variable-speed synchronous generators connected to three-level converters. Instead of using additional sensors, the currents typically measured for control purposes are utilized. The neutral point current of the converter is also evaluated under generator faults. Encoder-tuned dynamic filters, based on Park transformation and Fourier coefficients, along with low-pass filters, are employed to detect the selected harmonics at variable speeds. The geometric loci of these components are proposed as a method to differentiate between healthy and faulty conditions. Simulation and experimental data are used to assess the sensitivity, selectivity, and detection time of this technique for different fault types, as well as its applicability to other generator models.