Analysis of virtual inductances on the stability of the voltage control loops for LC‐filtered voltage‐controlled voltage‐source inverters in microgrids

Abstract

Abstract Voltage‐controlled voltage‐source inverters (VVSIs) have been widely used in microgrids. Typically, LC filters are adopted by the VVSIs to improve the quality of the output voltage. Resonances of the LC filters that may cause oscillations to the VVSIs can be damped by well‐designed voltage controllers. However, the virtual inductance (VI) that is widely applied to improve power sharing between VVSIs will reduce the stability margin of the voltage control loop and introduce new oscillations on the LC filters even if the well‐designed voltage controllers have been used, which has not been reported in the literature. Furthermore, since the VI will introduce a cross‐coupling into the system, the conventional methods for analyzing the resonances of the LC‐filtered VVSIs cannot be used for analyzing the oscillations caused by the VI. Therefore, the stability of the LC‐filtered VVSI with the VI is investigated based on a new model proposed in this paper. Besides, to enhance the stability of the VVSI, the application of a low‐pass filter or a band‐pass filter in the VI is studied. Moreover, when connecting the VVSIs, the effects of the line impedance on the stability of the VVSIs while using the VI are investigated. Finally, simulation and experimental results have been provided, which verifies the correctness of the analysis in this paper.

Keywords

• Voltage control
• Control of electric power systems
• Distributed power generation
• Power convertors and power supplies to apparatus