Power flow management method and controller using the same

A controller disposed in a power system, wherein the power system comprises a power providing module and a multilevel converter module, and the controller comprising:

• a component extracting circuit configured to obtain a plurality of sensed voltage signals and a plurality of sensed current signals between the power providing module and the multilevel converter module, and to generate a plurality of positive-sequence voltage signals, a plurality of positive-sequence current signals, a plurality of negative-sequence voltage signals and a plurality of negative-sequence current signals according to the sensed voltage signals and the sensed current signals;
• an average value calculating circuit configured to obtain a plurality of DC (direct-current) voltage signals from the multilevel converter module, and to calculate a plurality of averaged values and an overall averaged value according to the DC voltage signals;
• and
• a zero-sequence voltage generating circuit coupled to the component extracting circuit and the average value calculating circuit, and configured to calculate feedforward power according to the positive-sequence voltage signals, the positive-sequence current signals, the negative-sequence voltage signals and the negative-sequence current signals, and to calculate feedback power according to the averaged values and the overall averaged value, and to determine real power of a zero-sequence voltage injection signal according to the feedforward power and the feedback power, and to determine an magnitude and a phase of the zero-sequence voltage injection signal according to the real power of the zero-sequence voltage injection signal, the positive-sequence current signals and the negative-sequence current signals.