Series-Connected Adaptive Stabilizer for the Grid Connected Inverter at Weak Grid

This paper proposes a series-connected adaptive stabilizer (SAS) to fix the instability problem between the grid-connected inverter (GCI) and the weak grid via shaping the grid impedance. Different from the traditional stabilization method, the SAS does not need to know the information about the GCI, therefore, it can be treated as a module stabilization method. In addition, since the SAS is in series with the GCI and the grid impedance, it only goes through very small power. Moreover, the SAS is realized by a very simple adaptive current controller without any additional phase locked loop (PLL) and hence, is very easy to be implemented in the real world. Besides, the SAS also can match different GCIs automatically. Finally, an LCL type GCI is tested to verify the correctness of the proposed SAS.