自由金属微粒缺陷是气体绝缘全封闭组合电器（GIS）设备中频繁发生的放电缺陷类型之一，该类别缺陷具有粒子运动特征，导致对绝缘介质的损伤更为严重。对其尺寸参数和放电严重程度的准确估计有利于掌握设备绝缘损伤情况，提供具有针对性的检修与维护指导意见。本文提出基于数字虚拟测试的GIS内部金属微粒尺寸估计方法，基于数字化推演所得微粒坐标序列，结合金属微粒往返运动特性及其仿真分析，从而建立起微粒尺寸与其运动行为的关系，实现金属微粒尺寸的在线估计。仿真研究验证了本文所提方法的可行性与准确性，为基于数字化技术推演GIS设备内部绝缘状态提供思路。

Free metal particle defects are one of the frequent types of partial discharge defects in gas insulated switchgear (GIS) equipment, which have particle motion characteristics and cause more severe damage to the insulation medium. Accurate estimation of its size and severity of discharge is beneficial for understanding the insulation damage of equipment and providing targeted maintenance and repair guidance. This article proposes a method for estimating the internal metal particle size of GIS through digital virtual testing. Based on the particle coordinate sequence obtained from digital inversion, combined with the back-and-forth motion characteristics and simulation analysis of metal particles, the relationship between particle size and its motion behavior is established, thereby achieving online estimation of metal particle size and discharge capacity. The simulation study verified the feasibility and accuracy of the method proposed in this article, providing ideas for inferring the internal insulation status of equipment based on digital technology.