Study on the Evolution Mechanism and Flashover Warning of Multi-Modal Discharge of Metal Particles in Real GIS Under Long-Term Constant Voltage

This study investigates the discharge evolution of metal particle defects in GIS under long-term operating voltage using a 220 kV real-scale platform. By controlling particle length, quantity, and spatial distribution, we reveal key mechanisms: 1) Micron-scale particles exhibit dynamic migration and intermittent discharge, with alternating nanosecond pulses and millisecond micro-discharge clusters challenging conventional monitoring; 2) Particle position modulates discharge patterns-high-voltage triple-junction particles trigger sustained highdensity discharges, while surface-bound particles show delayed activation due to charge shielding; 3) High potential fixed particles (B3) and ground potential multiple particles (A2) have the highest discharge risk and need to be the focus of online monitoring. This work establishes quantitative links between particle parameters and discharge characteristics, supporting improved GIS monitoring and flashover warning reliability.