Parametric local stability condition of a multi-converter system
For power systems engineers, this provides a decentralized stability criterion that aligns with practical insights, though the result is incremental as it extends existing Lyapunov-based methods to a specific converter model.
The paper develops a decentralized parametric stability condition for a network of identical DC/AC converters, showing that sufficient reactive power support and resistive damping ensure local stability. The condition is explicit and generalizable to other systems like synchronous machines.
We study local (also referred to as small-signal) stability of a network of identical DC/AC converters having a rotating degree of freedom. We develop a stability theory for a class of partitioned linear systems with symmetries that has natural links to classical stability theories of interconnected systems. We find stability conditions descending from a particular Lyapunov function involving an oblique projection onto the complement of the synchronous steady state set and enjoying insightful structural properties. Our sufficient and explicit stability conditions can be evaluated in a fully decentralized fashion, reflect a parametric dependence on the converter's steady-state variables, and can be one-to-one generalized to other types of systems exhibiting the same behavior, such as synchronous machines. Our conditions demand for sufficient reactive power support and resistive damping. These requirements are well aligned with practitioners' insights.