Control design and small-signal modeling of multi-parallel virtual synchronous generators

With a high penetration of renewable energy in the grid, virtual synchronous generator (VSG) technology is proposed to be a solution for stability controlling of micro-source inverter. VSG can effectively solve the problem of renewable energy actively connected to the grid. This paper focuses on the control design and small-signal modeling of multi-parallel VSGs. Simplified virtual inertia controller of VSG is proposed to avoid the affect of frequency reference fluctuation on the system stability, and the small-signal model of multi-parallel VSGs which considers dynamic characteristics and the changing of steady state operation point is derived for system analysis and parameters design. Based on the small-signal model, the influence rules of the eigenvalues by droop constant, line parameters, VSGs parameters and parameters of low pass filter is acquired. Simulation and experimental results are shown to verify the feasibility and validity of the proposed method.