Research on internal faults of generators and their protection schemes in Three Gorges hydro power station

Based on the multi loop method, the internal faults of generators in China´s Three Gorges hydroelectric power station, including the interturn short circuit in the same branch, the short circuit of two branches of same phase and the short circuit of two branches of different phases are calculated. According to the calculated data of 60 short circuits of 2 generators, protection schemes are presented. Single element transverse protection is more the attractive scheme owing to its high sensitivity and simplicity. The high sensitivity single element transverse differential, noncomplete or complete longitudinal differential protections constitute multiple protection functions