Dynamic Phasor Modeling and Control of a Single-Phase Single-Stage Grid-Connected PV System

The increasing deployment of inverter-based sources in power systems and microgrids, and the concomitant reduction in system inertia, have made the study of system dynamic interactions and stability, essential. Detailed inverter models are accurate but computationally inefficient for such studies. This paper presents a dynamic phasor (DP) based model of a single-phase single-stage photovoltaic (PV) inverter. Compared to the existing DP-based PV inverter models in literature, the proposed DP-based PV inverter model includes the PV model and maximum power point tracking (MPPT) dynamics. The DP-based PV inverter model is then linearized around an equilibrium point and the resulting small-signal model is used to develop equations required for obtaining suitable control gains. The DP-based model is built on MATLAB/Simulink and then validated against a detailed model developed in Simulink/Simscope. Simulation results confirm the high efficacy of the DP model in predicting dominant harmonics in the AC/DC sides of the inverter, using a simulation step size 50 times larger than the detailed model's step size. The DP-based PV inverter model is well-suited for system-level study of inverter-based microgrids.