Minimization of local field enhancement along stress-grading systems of HV large rotating machines

Abstract

In this paper, an approach to the design of nonlinear stress-grading systems of high voltage rotating machines at different frequencies is presented. The parameters of stress-grading systems are selected to minimize the local electric field enhancement at a set of discrete operating frequencies. The nonlinear stress-grading resistances are updated in response to the dynamic change of the local surface field compared to the desired average field. This development allowed fast and accurate design and analysis of nonlinear stress-grading systems with the deviation of the highest local field from the desired average field kept very low over a frequency range of up to 300 Hz. Simulation examples and several optimal stress-grading system characteristics are also presented.