Research on the influence of switching frequency on the stability of large-scale distributed generation system

Abstract

Wind power generation is generally a large-capacity low-switching frequency power station, and photovoltaic power generation is generally a small-capacity high-switching frequency power station. Large-scale access of different types of new energy power stations increased risk of grid voltage fluctuations. Therefore, in order to analyze the variation law of the stability of different types of new energy sources connected to the weak grid, it is very important to analyze the stability of inverters with different switching frequencies, but there are few studies on this issue. In this paper, the detailed sequence impedance model of the current-controlled inverter is firstly established, and its correctness is verified by frequency sweeping. Secondly, considering the control bandwidth, ripple suppression and filtering performance, the filtering parameters of inverters with different switching frequencies are designed using a unified standard. On this basis, the stability criterion based on impedance ratio is used to analyze the stability variation law of inverters with different switching frequencies under strong and weak grid conditions. Finally, the correctness and accuracy of the theoretical analysis are verified by simulation experiments.

Keywords

• Switching frequency
• Grid-connected inverter
• Filter parameter design
• Weak grid