A Finite Element Analysis Model for Internal Partial Discharges in an Air-Filled, Cylindrical Cavity inside Solid Dielectric

The reliability of electrical equipment is closely tied with the health of their insulation system. A well-known symptom of the aging phenomenon in dielectrics is partial discharge (PD) which can occur in all media. Internal PDs in solid dielectrics occur in air-filled voids which are difficult to eliminate thoroughly and may appear simply during the manufacturing process. Although much research on PD measurement for solid dielectrics has been conducted, this is not the case for PD modeling. Besides, the simulation of a case study and its comparison with experimental results can provide further insights into the possibility of other PD sources. In this paper, a finite element analysis (FEA) model for internal PD in an air-filled cylindrical void inside a solid dielectric under 60 Hz sinusoidal voltage is developed. For the estimation of the parameters of the model, experimental data is needed. To this end, a cylindrical void was artificially made within a 3D-printed polylactic acid (PLA) block. Then, phase-resolved partial discharge (PRPD) patterns were measured for the mentioned samples. Using deterministic PD measurement data, an FEA model was developed. This model will help us understand and explain internal PD behavior for the case of a cylindrical void and study the influence of void size on PD behavior.