Stability analysis and parameter configuration of parallel virtual synchronous generators in microgrid

Abstract

The current small-signal stability analysis and parameter selection of converters that mimic synchronous generators usually ignore some dynamic characteristics and the changes of steady-state operating points for simplicity. It could only judge the trend of small-signal stability and the analysis result was not accurate enough. Firstly, this paper established a small-signal model that mimics synchronous generators by connecting two isolated converters in parallel, the eigenvalues of the system were calculated and some of their physical meanings were obtained. Following that, in order to demonstrate the relationship of eigenvalues and state variables, the participation factor was calculated. Considering that, there will be some variability of the operating points with the parameters variation. As a function of the system settings, numerous root locus plots were created. For individual eigenvalue close to the real axis, in order to reveal the contribution of different parameters to the oscillation patterns, a separate eigenvalue sensitivity analysis was performed. The rules of the influence are essential to guide the design of parameters and their optimization of isolated converters connected in parallel that mimic synchronous generators.

Keywords

• Small-signal model
• Parameter configuration
• Participation factor
• Distributed generation
• Virtual synchronous generator