T-S Fuzzy Model Based Large-Signal Stability Analysis of DC Microgrid With Various Loads

DC microgrid offers high efficiency, simple control, and reduced conversion stages advantages, but suffers from induced instability caused by its low inertia. Due to the strong nonlinearity of the DC microgrid, the analysis of its large-signal stability (LSS) is a very challenging task. This paper uses the T-S fuzzy model (TSFM) method to investigate the LSS of the DC microgrid with various loads, which is connected to the AC grid. The TSFM of the DC microgrid with grid-connected voltage source converter (VSC) as the main power supply is established. The analysis of the LSS of the DC microgrid is carried out using an estimate of the domain of attraction (DOA) of the working point. On the basis of the DOA, the effects of different types of loads and system parameters on the LSS are researched. The research results can serve as a guideline for adjusting the physical and control parameters to solve the DC microgrid instability problem. Finally, the large-signal stability analysis (LSSA) of the DC microgrid is performed using the MATLAB/Simulink simulation platform. The results of the simulation confirm the rightness of the proposed LSSA approach. They indicate that constant power load (CPL) has the greatest effect on the LSS of the DC microgrid compared to the constant impedance load (CIL) and the constant current load (CCL). In addition, the results of the time-domain simulation also validate the effectiveness of this method, which is a way to enhance the LSS of the DC microgrid through the adjustment of system parameters.