Abstract: In response to the issue of equipment damage and impact on grid stability caused by generator stator grounding faults, this paper conducts an in-depth study on the application of injecting external power through voltage transformers in stator grounding protection. The principle mechanism of the voltage transformer injection method is analyzed, and protection parameters are optimized based on field test data. The results show that this method can achieve grounding fault detection within 100% of the stator winding range, and still maintains high sensitivity in high-resistance grounding scenarios, providing reliable protection for the safe and stable operation of generators.