Research and application of protection relay schemes for internal faults in stator windings of a large hydro-generator with multi-branch and distributed arrangement

Along with the development of the electric power industry, the protection for internal faults of large hydrogenerators with multi-branch and distributed neutral arrangements has become more and more important. The internal short-circuit current may be several times larger than the terminal short-circuit current inside the stator windings, and such strong current could cause severe heat and mechanical damage. The authors discuss various relay protection schemes for internal hydrogenerator faults. They briefly describe the multi-loop method for the analysis of such internal faults