Numerical research on electromagnetic wave in ultra-high frequency band excited by partial discharge in electrical equipment

By finite difference time domain (FDTD) method with uniaxial perfectly matched layer (UPML) boundary condition, the comparison of the absorption effects between perfectly matched layer (PML) and UPML is performed, and the numerical discretization and iteration processes are deduced. Taking gas insulating switchgear (GIS) partial discharge (PD) as an example, the simulation model of electromagnetic (EM) wave is constructed, and the numerical stability condition and dispersion are discussed. The differences under hard source and soft source excitations are illustrated, and the GIS PD simulations at UPML and PML boundaries are also compared. It is revealed that the absorption of EM waves with UPML boundary condition is better than that with PML. The hard source and soft source of pulse current excitation can be employed to simulate the PD EM waves generated by metal and non-metal defects, respectively. The peak-peak value of EM wave under hard source is about five times larger than that under soft source. The largest electric field strength component inside GIS is perpendicular to the direction of travelling waves in GIS, and the largest electric field strength component of the leakage EM waves is along the direction of travelling waves in GIS. The main frequency spectrums of EM waves comply with the different waveguide modes in GIS. The difference between inside and leakage EM waves is caused by the self frequency response characteristic of the slot antenna formed by the insulating spacer and bolts.