An Inertia Emulation Method Based on Improved Double-Loop Control for Grid-tied Inverters

A large amount of distributed generation is connected to the grid, reducing rotational inertia of the power system. Based on the Static Synchronous Generator Model, inertia controller is introduced on outer voltage loop in this paper to enhance grid inertia. The developed inertia controller can generate inertial current superposed in conventional current reference. The inertial current can be adjusted arbitrarily, consequently realizing the equivalent emulation of inverter inertia on the basis of the conventional double closed-loop control. In addition, the physical mechanism of the developed inertia controller is investigated. The experimental results show that the presented method can adjust the inertia of grid-tied inverters flexibly, and enhance the system stability.