Electric Field Simulation Analysis on the End of Stator Winding for Large Generators

In order to study the anti-corona performance of the stator end winding of a large generator, this paper takes the stator end winding of an 18kV hydroelectric generator as the research object to conduct simulation analysis. Firstly, three out-of-phase stator winding models were constructed based on two possible anti-corona structures that may be used for the stator bar of the generator. Then, finite element electric field simulation analysis is conducted using COMSOL Multiphysics software. The research results indicate that a sudden change in the potential of the stator winding at the low resistance and high resistance overlap points of the high-voltage bar as well as at the binding position of the diagonal edge of the bar occurs. The maximum value of the winding air gap field strength occurs in the air domain between the medium and high resistance overlap points of the two stator bars, and the maximum value of the loss distribution occurs at the low resistance and high resistance overlap areas of the highvoltage stator bar. The simulation results show that as the excitation voltage increases, the distribution of potential, electric field, and loss gradually increases. Moreover, under different assessment voltages, all three winding models meet the requirements for the anti-corona performance of the generator stator winding. This indicates that the mixed use of different anticorona structures has a relatively small impact on the distribution of electric field at the end of the stator winding. In addition, in the actual production, attention should be paid to the anti-corona treatment in the area with concentrated electric field distribution, so as to avoid corona discharge, ablation and even winding gap breakdown during the operation of the generator.