Small-signal modeling and characteristic comparative analysis for a single grid-connected grid-forming VSG with full-order and second-order

Abstract

The single-machine grid-connected grid-forming virtual synchronous generator (GFVSG) small signal mathematical model is divided into full-order and second-order small signal mathematical models according to whether power calculation, voltage plus current bottom double loop and AC filtering are considered in the modeling process. And the difference of mathematical models has an important impact on the accurate analysis of GFVSG grid-connected active power dynamic response characteristics (GCAP-DRCs). For this reason, the full-order and second-order small signal mathematical models of GFVSG grid-connected system are established, then their GCAP-DRCs are compared and analyzed. The results show that the second-order model and the full-order model of GFVSG grid-connected system have similar GCAP-DRCs, thus the second-order model can be directly used to replace the full-order model to study the GCAP-DRCs of GFVSG grid-connected system in engineering applications, so as to simplify the theoretical analysis process. Finally, the correctness of the mathematical model and theoretical analysis is verified by using MATLAB/Simulink software simulation and experiment.

Keywords

• Grid-forming virtual synchronous generator
• Small signal mathematical model
• Grid-connected active power
• Dynamic response characteristic
• Second-order model
• Full-order model