Given a development goal of "carbon peak and carbon neutrality", the penetration of new energy power generation has been increasing year on year. However, problems such as poor fault ride-through capability and uncertain power output are increasingly prominent. Traditional generators have large capacity. As the main supporting power sources of the system, their power regulation and safety support effects are important, and it is particularly urgent to enhance the performance and function of their relay protection. To configure and improve the generator protection principle, it is necessary to deeply associate with the fault mechanism and extract the fault characteristics. In this paper, the unbalanced current’s generating mechanism of the generator zero-sequence transverse differential protection is analyzed. The conclusion is drawn that it is proportional to the main air gap Electromotive Force (EMF). Thus, a zero-sequence transverse differential protection criterion based on the air gap EMF brake is proposed. This can improve protection sensitivity under internal short-circuit faults with small turn-difference. Based on the in-depth analysis of the fault risk under single-phase stator ground faults, the ground fault current is used to reflect the fault risk. Then, a corresponding stator ground fault protection is proposed, one which can adaptively determine the tripping mode according to the security risk. Research results are intended to provide technical ideas for the improvement of large generator protection. This work is supported by the National Natural Science Foundation of China (No. 51877089).