Improved Damping Control of Grid-forming Inverter Using DC Dynamics

The DC side of the grid-forming inverter is usually simplified as an ideal source when considering the AC dynamics. However, the DC dynamics actually contain useful information of the AC side. This paper proposes an improved damping control for the grid-forming inverter using the DC dynamics. The error of the DC voltage is introduced into the active power loop through a proportional controller. As a result, an extra freedom in addition to the virtual inertia can be adjusted. A small-signal analysis is carried out in detail to study the impact of the DC dynamics. Compared with other damping methods, the proposed method can simultaneously improve the performance of not only the AC side but also the DC side without increasing the order of the system The simulation results verify the effectiveness of the proposed method.