Dynamic Stability Improvement and Accurate Power Regulation of Single-Phase Virtual Oscillator Based Microgrids

Abstract

Thanks to its fast self-synchronization capability, the virtual oscillator control (VOC) has become an emerging control technique for grid-connected inverters, especially in single-phase applications. Nevertheless, the nonlinearity of VOC inverters impacts its dynamic behavior, and there is a trade-off between the system stability and accurate power regulation in VOC-based microgrids. This paper studies the dynamic stability of VOC inverters for guiding the parameter design. Then, based on the analysis result, an improved VOC strategy with hybrid power regulation structure is proposed for improving both the system stability and power regulation of VOC-based microgrids. First, a dynamic phasor (DP) model of single-phase VOC-based microgrids with multiple control loops is developed. Second, a stability region analysis of VOC parameters is performed, the proper mode setting and robust parameter design of VOC inverters are provided. Third, the improved VOC strategy is presented, achieving accurate power sharing, fast voltage recovery and adequate stability margin. The proposed parameter design and improved VOC strategy are validated by simulation and hardware-in the-loop experiment.