Coupled Eddy Current And Temperature Fields Analysis Of Large Hydro-generator

The rated capacity of a large hydro-generator is being increased continuously and significantly since 1960s. Consequently, the end region of the generator is suffering from heavy overheating problems. The overheating is one critical factor to restrict the capacity of the generator. Therefore, relevant researchers conduct a lot of analysis and experiment research on the overheating problems in the past few decades. In this regard, the disertaion focuses on the three dimensional coupled eddy current and temperature field of the end region of a 100 MW hydro-generator in different operating conditions. The main works and research findings are summarized as:Firstly, based on the prototype motor and the characteristics of the finite element simulation, we develop the finite element model of the end region of the hydro-generator. This model is considered as an appropriate one for simulation, because it keeps the key parts which have a relatively large influence on the simulation result, and ignores the unnecessary details which have a relatively low influence on the simulation result but will largely occupy the computer calculation resources.Secondly, we emphatically discuss and solve three problems encountered in the process of simulation analysis. One is the determination of the theoretical calculation of the field current and the armature current phases. To solve this problem, we propose a numerical correction method based on the theoretical calculation according to the basic law of electromagnetic field in the actual operation of the motor. Another one is the mesh problem when facing a conductor with a serious skin effect. An approach to effectively deal with the serious skin effect is introduced to avoid calculation failure as a result of finite mesh overflow. The last one is the calculation of coefficient of heat transfer. We calculate the coefficient of heat transfer and determine the thermal field boundary conditions of the key parts of the end region using a lot of practical engineering experience and methods.Finally, using the finite element simulation software MagNet and ThermNet based on the theoretical analysis and simulation experience, we obtain the electromagnetic field and temperature field distribution in the end region of the hydro-generator in no-load、rated、 leading phase 0.95、leading phase 0.8 operating conditions. The related methods and simulation results will provide a good reference for the engineering and technical personnel and relevant scientific research personnel.