Experimental Validation for Impedance-Based Small-Signal Stability Analysis of Single-Phase Interconnected Power Systems With Grid-Feeding Inverters

The interactions of more and more power electronics-interfaced power systems can worsen the power quality and the system stability in distribution networks. System stability can be addressed by analyzing the source and load impedances at the interaction section, and well-established approaches exist for dc and three-phase ac networks. Some papers also focused on single-phase ac systems, whose study is generally more difficult due to their time-varying characteristics. Similar to the approaches based on $dq$ rotating frame impedances, this paper focuses on single-phase systems using the dynamic phasor approach to determine the 2-D source and load impedances. The system stability is then evaluated using the generalized Nyquist stability criterion. As an example of application, a single-phase ac system that includes a current-controlled inverter synchronized to the grid through a phase-locked loop is proposed. Experimental validations are provided herein to verify the feasibility of this approach and the stability criteria based on the 2-D source and load impedances in the single-phase systems.