Current‐Limiting Strategy for Unbalanced Low‐Voltage Ride Through of the SMSI‐MG Based on Coordinated Control of the Generator Subunits.

Unlike the inverters in the traditional alternating‐current (AC) microgrid, those in a microgrid with series microsource inverters (SMSI‐MG) are connected to the power grid after being cascaded. The authors of this study first divide the control sections according to the degree of grid voltage dips and formulate a coordinated scheme to suppress fluctuations in the output powers of the SMSI‐MG. For the section in which the degree of unbalanced grid voltage dips is relatively low, a current‐limiting strategy that reduces the output power of the SMSI‐MG through the coordinated control of the generator subunits (CCGU) is proposed. More active power can be provided by the SMSI‐MG when the proposed strategy is used, than in the strategy that is based on changing the reference power, and the output reactive power of the SMSI‐MG can be automatically changed with the degrees of dip and unbalance of the grid voltage. The Light Gradient‐Boosting Machine (LightGBM) is used to establish a mapping relationship between the parameters characterizing overcurrent and the reduction quantity in output active power of the SMSI‐MG to implement the CCGU‐based current‐limiting strategy. The complex collaborative control is simplified to improve the low‐voltage ride through (LVRT) capability of the SMSI‐MG. [ABSTRACT FROM AUTHOR]