GFM-GCI 系统正负序电压电流环控制框图及工作原理

The control block diagrams for the positive-sequence and negative-sequence voltage-current loops of the GFM-GCI system are shown in Figure 3(a) and (b) respectively. The output U+ of the positive-sequence reactive power droop control loop is used as the reference value for the positive-sequence d-axis voltage at the grid connection point. The output U- of the negative-sequence reactive power droop control loop is used as the reference value for the negative-sequence d-axis voltage at the grid connection point. The reference values for the positive-sequence and negative-sequence q-axis voltages at the grid connection point are both set to 0. By using PI controllers for the positive-sequence and negative-sequence q-axis voltage loops, the positive-sequence and negative-sequence q-axis voltages at the grid connection point are always controlled to 0. Therefore, the output voltage of the GFM-GCI system always aligns with the d-axis of the synchronous rotating coordinate system.