Three-phase four-wire system power quality comprehensive treatment device and control method and system thereof

The invention relates to a three-phase four-wire system power quality comprehensive treatment device and a control method and system thereof. The method comprises correspondingly processing a load current to obtain a zero-sequence current component and a negative-sequence current component; correspondingly processing the load current and a DC support capacitor voltage to obtain three components which are used as the input reference values of a zero-sequence current control loop, a negative-sequence current control loop and a positive-sequence current control loop respectively; modulating a zero-sequence adjustment signal output by the zero-sequence current control loop output, a positive-sequence adjustment signal output by the positive-sequence current control loop, and a negative-sequence adjustment signal output by the negative-sequence current control loop to generate a control signal of a switching device to perform dynamic compensation control. The method performs positive-sequence, negative-sequence an