The utility model discloses a SVG based on three level NPC technique, through sampling detection circuitry, detect the voltage in the load, the electric current, calculation through digital signal processor DSP+FPGA obtains the reactive current in the load, then produce the samely with load reactive current phase place through the PWM isolating driver control power circuit, the opposite reactive current of size, reactive current cancel each other out in offset current and the load, finally reach compensating system power factor's mesh. Compare two level converters, at three level converter commutation in -processs, every IGBT all only bears the half the of direct current side total voltage, has improved the equipment capacity, reduce cost to have advantages such as output voltage, current harmonic is low, electromagnetic interference is little. Offset harmonic, the idle and uneven weight that need compensate among the load current, finally obtain the supply current of expectation to realize electric wire netting reactive power's continuous accurate compensation on a large scale.