Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 72555
Stator Intermittent Ground Fault Detection in High-Impedance Grounded Generators

Authors: Nader Safari-Shad, Russ Franklin

Abstract:

The paper shows that stator intermittent ground fault (IGF) events in high-impedance grounded (HIG) generators cannot always be dependably detected using the conventional and some new proposed IEEE protection schemes. Hence, a novel subharmonic current differential scheme is presented for the reliable detection of IGF events. The key advantage of the new scheme is that it uses an already available neutral grounding current signal in the existing subharmonic injection protection circuit of HIG generators, and as a result, it does not require any additional current transformers or hardware. The performance of the proposed scheme is evaluated using simulations with field captured data from a 618 MVA generator.

Keywords: high-impedance grounded generators, stator intermittent ground fault protection, fundamental neutral ground overvoltage, third-harmonic and subharmonic voltage injection schemes

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