With regard to voltage flicker and fluctuation, three-phase imbalance and harmonic wave of the power grid, the solutions based on Passive Filter (FC), Static Var Compensator (SVC), Static Var Generator (SVG), Active Power Filter (APF) and Dynamic Voltage Restorer (DVR) are used. In this way, the reactive power can be regulated to support grid voltage, to eliminate the harmonic pollution and to compensate the unbalanced current of the load, realizing comprehensive quality control of electric energy.