The Huge Hydro Generator Main Protection Scheme Analysis And Its General Software Development

China has programmed to vigorously develop hydropower in successive five-year plans, numbers of huge hydropower stations are or have been developed and put into use, and the generator's capacity is also growing. The Large-capacity generator plays an important part in the power system, its fault would seriously affect the unit itself and the security and stability of power system, so it is very important to set the effective protection scheme on the generator.The huge hydro generator's stator uses the multi-branched structure, which makes complex connection types of neutral point and multiple protection schemes, as the generator's different structures and parameters make the optimized protection scheme complicated, it is very important to develop general software of main protection (complete longitudinal differential protection, non-complete longitudinal differential protection, single element transverse differential protection, split transverse differential protection) analysis.The dissertation has developed the general software for the hydro generator main protection analysis by using the object-oriented programming tool Visual C++ 6.0. The software has good interface, on the outcome of the fault simulation, it chooses the different the branch combination way of two or three neutral points and compares the protection effects under each type of protection scheme, then it gives the most optimized scheme after comparative analysis.Based on simulating and analyzing all the possible fault of DEFM hydro generator in Three Gorges right bank project, the dissertation adopts the developed protection analysis software, analyzes and researches ABB, Siemens and Xuji protection sensitivity when the connection types of neutral point is 123-45, the conclusion has been used in the main protection scheme of DEFM hydro generator.The comparation of protection sensitivity must be based on that it doesn't operate when external fault occurs, the fast protection should correct action in tripping before the transient process end, and the current transformer (TA) saturation may lead to protection operation when external fault occurs. It is necessary to study the current transformer transient characteristics to make the relaying act correctly. The dissertation analyzes the factors that cause the current transformer saturation by the theory and simulation, and modeling the TA transient characteristics when generator external three-phase short circuit occurs by MATLAB. The numerical short-circuit current generated by internal fault may cause zero-sequence transverse differential current transformer saturation, The dissertation also analyzes the effect on the zero-sequence transverse differential current transformer saturation when TA ratio is changed, then studies how to select zero-sequence differential current transformer.At the end of this dissertation, a systematical summary is given and further work to be studied is pointed out.