A Novel Protection for Stator Winding Grounding Faults in Multi-Generator-Systems

A power generation system with more than one generator directly connecting a bus is defined as a multi-generator-system (MGS). Most small or medium power generation systems are MGS with neutral point ineffectively earthed. While grounding faults occur in the systems, every parallel generator has the same voltage, and traditional stator winding grounding fault protections with zero sequence voltage cannot detect which generator faulted. It is discovered in the paper that he stator winding phase-to-ground leaking current in the faulted generator is much larger than that in the sound generators. And the leaking current in every sound generator is almost equal. A novel protection with the phase-to-ground leaking currents comparing is hence proposed. EMTP simulation results show that the protection can detect grounding faults with resistance 1 kOmega in 90% of the winding. Another protection with the third harmonic leaking current comparing to protect faults in the neutral point area is now in progressing