VSG Simplified Damper Winding: Design Guidelines

The growing spread of renewable energy sources has brought the issue of providing virtual inertia to the electric power system. Virtual Synchronous Generators (VSGs) are a valid solution capable of adding inertial behavior to static grid-tied converters. While many VSG solutions are available in the literature, the proper tuning of the virtual parameters is an open issue. In particular, this paper focuses on the VSG damping using a virtual damper only on the q-axis. Starting from a brief summary of the q-axis damper winding structure, the linearized electromechanical model of such VSG is derived. This model is then used to obtain the analytical relationships between the virtual damper parameters and the dynamic behavior of the machine during electromechanical transients. Guidelines to tune the most suitable damper parameters are given, in order to obtain certain dynamic behavior from the grid side. Finally, the proposed design procedure is validated experimentally on a 15kVA grid-tied inverter.