Frequency domain algorithm in the whole process simulation from VFTO to its conducted disturbance via voltage transformer in GIS substations

Simulation of very fast transient over-voltage (VFTO) and its conducted disturbance via voltage transformer (VT) is significant in guiding the insulation design and electromagnetic compatibility of gas-insulated switchgear (GIS) substations. However, the commonly used time-domain algorithms are difficult to deal with the complex frequency-dependent parameters in the VFTO simulation, and might introduce instability of conducted disturbance due to an active circuit synthesis of the VT in some cases. In this paper, a frequency-domain algorithm is proposed, which calculates the VFTO in the frequency domain and then directly uses the VFTO frequency spectrum and the VT transfer function to calculate the conducted disturbance without circuit synthesis. The proposed algorithm has been applied in the simulation of VFTO and its disturbance in the 1000 kV Wuhu substation. The calculated and measured VFTO waveforms are in good agreement, verifying the accuracy of the algorithm. The transfer functions of the 1000 kV GIS VT are obtained by the impulse test method, and the conducted disturbances are also calculated with their severity and suppression method analyzed. The proposed frequency-domain algorithm covers the whole calculation process from VFTO to its conducted disturbance and has good engineering application potential in the simulation, with better convenience and stability.