LADRC-Based Large-Signal Stability Enhancement for Microgrid Energy Storage Converter

To maintain the stability of the bus voltage in a DC microgrid, the voltage-current double PI closed-loop control method is frequently applied in the energy storage converter, specifically the DC/DC converter. However, the robustness of the DC/DC converter under voltage-current double PI closed-loop control method is relatively weak. In addition, because the power converter-based load exhibits constant power characteristics, this introduces nonlinearity and negative impedance characteristics to the DC microgrid, which affects the system stability when subjected to disturbances and sudden load changes, making the traditional small signal analysis no longer applicable. To address this challenge, a strategy based on linear active disturbance rejection control (LADRC) is proposed and used into the DC/DC converter to enhance the stability of the system. A simplified large signal model of the DC microgrid system with LADRC is established. In addition, based on the developed model, the region of asymptotic stability (RAS) of the system is depicted by using the TS fuzzy modeling method and the limit power is estimated and both are compared with the conventional control. Finally, the accuracy of the modeling and the effectiveness of the proposed control strategy are verified by simulation and calculation of the limit step power of the system.