Characteristics of very fast transient currents in ultra high-voltage power system with Hybrid reactive power compensation

•The equivalent model of HRPC is developed. The expression of VFTC in time domain is deduced using Inverse Laplace Transform.•The amplitude and frequency of VFTC are jointly affected by the capacitances of SCSR and SC, the line length and the stray capacitances, etc.•The oscillating frequency, the peak and the amplitude corresponding to the main components of VFTC can be modified by means of adjusting the silicon controlled rectifiers in SCSR.•As the DS in SC is switched on, the frequency and the peak value of VFTC is quite large. Increasing the line length between the SC and the SCSR can effectively suppress the VFTC in UHV power system.