Partical Discharge Pattern Analysis of Metallic Particle Influence on Polymer Surfaces in MVDC Stations

Recent research has been focused on expanding distributed power generation using renewable energy sources and applying DC technology to power grids. As an alternative, MVDC (Medium Voltage Direct Current) technology has attracted attention, but standards for operating MVDC stations have not yet been established. For reliable operation of MVDC stations, diagnosis technology to prevent accidents is needed. Real-time monitoring and diagnosis methods, such as partial discharge measurement, face difficulties due to noise from surrounding high-voltage equipment in the MVDC station environment. Furthermore, the coexistence of AC and DC high-voltage components leads to complex voltage stresses, making analysis and interpretation of partial discharge data difficult. One of the main causes of accidents in MVDC stations is insulation failure accidents caused by metallic particles adhering to polymer insulator surfaces such as bushings and support insulators. Therefore, in this paper, metallic particles were attached to polymer surfaces to simulate surface discharge caused by metallic particles. Metallic particle of sizes 5mm, 7mm, and 9mm were selected to analyze surface discharge characteristics based on metallic particle size. The reliability of defects was verified using the AC partial discharge pattern analysis method PRPD(Phased Resolved Partial Discharge). Finally, the DC partial discharge signals were analyzed using PSA(Pulse Sequence Analysis) and TF(Time-Frequency) map, and the DC partial discharge patterns based on metallic particle size were derived. It is expected that this research will contribute to preventing accidents caused by metallic particle adhesion during manufacturing processes and operation.