Analysis of Inertia and Damping Characteristics of Grid-connected Photovoltaic Power Generation System Based on Droop Control

The grid-connected photovoltaic power generation system (GPPGS) with high proportion of renewable energy has the ability to load balance. A strategy is proposed for GPPGS based on droop control. The electric torque analysis method (ETAM) is used to establish mathematical model of the system with DC voltage timescale (DVT) and analyze the influence law of inertia, damping and synchronization characteristics from the physical mechanism perspective. The research finds that the equivalent inertia, damping and synchronization parameters of the system are determined by the control parameters, structural parameters and steady-state operating point parameters. Changing the control parameters is the simplest and most flexible way to influence the inertia damping and synchronization ability of the system. The inertia characteristics of the system are greatly influenced by the control parameter Kp and enhanced with the increase of Kp. The damping characteristics of the system are obviously affected by the control parameter Dp and weakened with the increase of Dp. The synchronization effect of the system is only controlled by the parameter Ki and enhanced with the increase of Ki. The effectiveness and correctness of the analysis conclusion are verified by simulation.