The authors proposed controlling processes of capacitor reactive power compensation by adjusting voltage with thyristor in operating and grade-changing situations

set up state parameter equations of various processes for single-phase test device

stimulated and analyzed the transient current of the device and the disconnected voltage on thyristor switches in operating and grade-changing processes with digital integral.The simulation results are in accordance with the test ones

indicating that the device perform well in operating and grade-changing processes.This research may offer a reference for grade-changing control design.