Linear and Uniform System Dynamics of Future Converter-Based Power Systems

The share of power converter based renewable generation is steadily increasing at the expense of rotating inertia. Virtual Synchronous Machines are deemed to ensure system stability, however, there are no widely accepted criteria for the design of their controllers. In converter-dominated power systems one of the main challenges will be to analyze large-signal stability, because of the large number (and possibly divergent design) of converters. Converters, however, also offer the possibility to shape system dynamics in a way that was impossible with synchronous machines. In this paper we introduce the new concept of Linearized and Uniform Swing Dynamics. This allows to linearize the nonlinear swing equation over almost the entire state space, thereby enabling to use the small-signal stability analysis technique for large signal stability investigations. By properly choosing the controller parameters, the dynamics of the large number of converters expected in the system can be made unified and predictable.