Digitalization is an important direction for condition assessment of power equipment

whereas its application to partial discharge(PD)detection remains exploratory. To address the separation among analyses of the microscopic discharge process

electromagnetic propagation

and sensor response in existing studies

a three-stage sequentially coupled simulation model covering air-gap discharge

electromagnetic propagation

and antenna response was proposed for PD caused by air-gap defects in insulating media. First

the air-gap discharge process was simulated using a charge fluid model

and the time-varying charged-particle distribution

electric-field distribution

and equivalent discharge current were obtained. Then

based on the finite-difference time-domain(FDTD)method

the receiving antenna was incorporated into the electromagnetic simulation domain

and the equivalent discharge current was used as the excitation source to analyze electromagnetic radiation and propagation. Finally

an equivalent circuit of the antenna-coaxial cable-oscilloscope system was established according to transmission-line theory

and the observed waveform at the measurement port was obtained. The experimental results show good agreement between simulation and measurement in discharge-current amplitude

waveform characteristics

and spectral distribution. The model can simulate the full process of PD monitoring and provide a theoretical basis for digital twins and condition assessment of power equipment.