Research on improving sagging control strategy based on distributed inverter

In microgrids, sag control strategies are commonly employed by inverters across various levels. This study introduces an innovative solution to address challenges in sag control, specifically targeting issues related to uneven reactive power distribution and present transmission line impedance causes the AC bus voltage to drop. The proposed approach involves the implementation of an adaptive virtual impedance method and a feedback bus voltage recovery strategy, both grounded in the principle of multibody consistency. Firstly, the paper analyzes the causes of uneven reactive power distribution and busbar voltage deviation caused by traditional inverter sag control with multi-inverters parallel model. Secondly, the improvement strategy of sag control is proposed, and the virtual impedance and bus voltage feedback method of control based on distributed consistency principle is introduced to achieve the purpose of reactive power equalizing and restoring bus voltage. Finally, two inverter models were built in the MATLAB/Simulink, validation of the proposed strategy and demonstrate the effectiveness of the proposed strategy. Simulation results show that the proposed strategy can effectively improve the performance of the system of rational reactive power distribution and stable bus voltage of multiple inverters and can provide reference for the parallel use of multiple inverters