Study On Stator Fault Modalities And Main Protection Schemes Of The Three Gorges Right Bank Generators

With the hydro-generator of Three Gorges Project being put into operation and many large and huge hydro-generator stations being contructed, the unit capacity of hydro-generator trends to become larger. The unit capacity of hydro-generators in Three Gorges Power Station is 700MW. Theses huge generators are the key equipment of the power system, which play important roles in the safety and stability of the hydropower stations, even for the whole electric power grid. Therefore, it is attractive to study on the internal fault regulation, internal fault simulation for this kind of giant hydro-generators and to design its protection layout reasonably to decrease the miss-tripping rate. This paper bases on the structure parameter and the stator-winding diagram of the giant hydraulic generators of the Three Gorges power station. Analyzes the structure of its stator winding and confirm the most possible position that short faults occur. Furthermore, an efficient searching algorithm used for auto-analyzing has been introduced. After the analysis of internal fault modality and locations have been done, Plenty of internal fault simulations and calculations have been carried out by adopting the developed transient simulation program. Based on which, a couples of protection setting suggestions have been made and take the statistical data of emulational protection tripping instance for referrence, the paper finally recommand a suit of protection configuration scheme which has got the best tripping characteristic. Electrical sequence map is the important gist of power system tidal current calculation and the setting value calculation of the main component protection. According to the connection form of the Three Gorges power station, an electrical sequence diagram auto-drawing software has been developed. Meanwhile, the principle and the tripping characteristic of some new generator protection abroad has been introduced.