Comparison of Different Simulating Calculation Methods for Electric Fields Along the Stator End-winding of HV Rotating Machine

The stress grading (SG) system is the important structure of stator end-winding of high voltage (HV) rotating machine, whose performance is closely related to the safe operation of HV rotating machine. How to evaluate the performance of the SG system is vital and helpful to the design and optimization of SG system. In this paper, the available numerical calculation methods, including conventional pi-type equivalent circuit method (PECM), complex reticular equivalent circuit method (CECM), and finite element method (FEM), were described. And the comparative analyses were made based on the potential and electric field distribution along the three-segment stress grading coating (SGC) of a rated 24kV class hydro-generator, which is obtained from three calculation methods. The results showed that three methods all could be applied to evaluate the performance of the SG system, but the complex reticular equivalent circuit method and finite element method are in agreement with each other and should be more suitable for the optimization design of the SG system of HV rotating machine.