Large Disturbance Stability Analysis of DC Microgrid with Constant Power Load Based on Sum of Square Programming Estimating Attraction Domain

In DC microgrids, constant power loads with negative impedance characteristics are prone to instability when the DC bus voltage is subjected to large disturbances. To ensure the stable operation of DC microgrids with constant power loads under large disturbance conditions, this paper proposes a large disturbance stability analysis method based on sum of square programming to estimate the maximum attraction domain. Firstly, a typical DC microgrid is simplified and its equivalent average mathematical model is established. Secondly, based on the sum of squares programming method, the domain of attraction of the DC microgrid with a constant power load is estimated. Then, the stability of this system under large disturbance conditions is analyzed based on the domain of attraction, and the influence of the system parameters on stability is studied. Finally, time-domain simulation based on MATLAB/Simulink verified the effectiveness of the proposed method in stability analysis and the correctness of the conclusions on the impact of system parameters on stability analysis.