Calculation for transient radiation field from metallic enclosure of GIS based on vector fitting and recursive convolution

A new method is proposed to calculate the transient radiation field from the metallic enclosure of a gas insulated substation (GIS). The frequency-domain Green´s function is firstly approximated using vector fitting, and can be written as the sum of exponential functions in the time-domain; then the transient radiation field is directly calculated using recursive convolution. It not only improves the accuracy and reduces the CPU time, but also avoids the conventional problems of FFT. A comparison between the numerical results and the measured results of a 125 kV GIS confirms the correctness and accuracy of this method.