Sensitivity Analysis of Different Controller Parameters on the Stability of the Weak-Grid-Tied Interlinking VSC

The stability problem arising from the DC-link voltage outer loop and current inner loop control in weak-grid-tied interlinking voltage-source converters (VSC) system has been extensively investigated. However, the different impacts on system stability caused by these controller parameters have not been well solved. A three-port hybrid AC/DC admittance-based model for VSC taking into account AC- and DC-side dynamics is developed for revealing the mechanism intuitively on the formation of the positive and negative feedback effects in the DC-link voltage control loop. Subsequently, the stability characteristics of the voltage outer loop and current inner loop controller parameters on VSC are analyzed. Compared to adjusting the voltage outer loop controller parameters which has significant effort on the dynamic regulation characteristics, it is more sensitive on system stability by the parameter change of the current inner loop controller. Theoretical results, along with experimental verification, are provided to validate the analysis.