Real time and fast switching, and the repeated switching time is less than 10ms; the imported thyristor module is adopted, with long overall service life; with current, temperature detection and display functions; with intelligent over-current protection, temperature protection, phase loss protection, thyristor breakdown protection, alarm and other functions; different status indications can be given according to the fault category, so as to facilitate troubleshooting. It can be divided into single-phase compensation, inter phase compensation and three-phase compensation, which can adapt to different application occasions; the capacitor does not need to discharge, no matter the residual voltage of the capacitor is any value, the capacitor branch can be put into operation in real time and without impact, and the current can be switched off when passing zero point, without switching on inrush current.