The STB enhanced static var generator (ASVG) detects the load current in real time through the external current transformer (CT), and extracts the reactive power components and harmonics of the load current after calculation by the internal DSP, and then sends the PWM signal to the internal GBT according to the It is set to control the inverter to generate reactive current and low-order harmonic current that meet the requirements, so as to achieve the purpose of reactive power compensation and harmonic control.