Large-signal Stability Analysis of Grid-connected DC Microgrid with VSC

Abstract

The grid-connected DC microgrid under the background of high penetrations of renewable energy sources and high penetrations of inverter-interfaced devices has the characteristics of strong nonlinearity and poor immunity, which leads to the problems of large-scale voltage fluctuation and instability when the grid-connected DC microgrid suffers large disturbances, and it seriously influences the security and stable operation of the system. Therefore, a large disturbance stability criterion which is based on the mixed potential theory (MPT) for the DC microgrid model with a grid-connected voltage-source converter (VSC) is proposed. This paper also analyzes the mechanism of the conservatism of the stability criterion, verifies the accuracy of the large disturbance stability standard, and analyses the influencing elements and basic mechanism of the large-signal stability (LSS) of the nonlinear systems, which provides a benchmark to design the parameters of the control of VSC and main circuit. Finally, the effectiveness and accuracy of the analysis are verified by electromagnetic transient simulation.