Stability Margins of Grid-Supporting Converters

This paper contains a small-signal stability analysis of grid-supporting converter systems. Therefore, the detailed control structure is used to develop approximated models which match the original behavior. To define the stability margins of a grid-supporting converter system, the state matrix eigenvalues of the linearized model are investigated. By adjusting the dynamics of the superposed functionalities as well as the operating and grid states the operating limits are defined and the influence of the variations is analyzed. Furthermore, a result analysis determines the conditions and dynamics that enable grid-supporting converter systems to assist and specifies the point at which these need to be replaced by grid-voltage-forming systems.