A Uniform Field Construction Method with a Dominant Parallel Component for Evaluating the Performance of Insulating Pressboard

The reliable operation of oil-immersed power transformers is crucial for the stability of power systems. By optimizing insulation structure design, the internal electromagnetic environment of modern transformers has approached a uniform electric field. However, the performance evaluation of insulating pressboards in existing studies and standards is often conducted under highly non-uniform electric fields, which significantly deviates from actual operating conditions. To address this issue, this paper proposes a method for establishing a uniform electric field on the surface of insulating pressboards. First, an initial design scheme is formulated based on a multi-ring electrode structure, integrating the advantages of plate-plate and sphere-sphere electrode configurations. Subsequently, a finite element model of the electrode system is constructed, and finite element analysis is employed to reveal the potential distribution and electric stress characteristics of the electrodes. Furthermore, a three-step optimization process, including multiple rings, size optimization, and end insulation, is implemented to progressively refine the electrode parameters. As a result, an optimal multi-ring electrode structure is determined, reducing the electric field non-uniformity coefficient on the pressboard surface to 1.133, thereby successfully establishing a uniform electric field environment. This study develops a “multi-step optimization-simulation feedback” research framework, providing a design paradigm for constructing a uniform electric field on the surface of insulating pressboards. Additionally, it offers an experimental design basis for evaluating the performance of insulating pressboards under realistic operating conditions.