A new approach to physics-based reduction of power system dynamic models

• A new approach to physics-based reduction of power system dynamic models, described by a set of differential and algebraic equations.
• Using the balanced realization theory (BRT), the original dynamic model is reduced, while preserving the physical meaning of retained state variables.
• Removing from the model the state variables that do not dominantly affect the nature of the phenomenon to be analyzed, as evidenced by the magnitude of the frequency response.
• Proposed algorithm is applicable for reduction of dynamic models of large-scale power systems.

This paper proposes a new approach to physics-based reduction of large-scale power system dynamic models, described by a set of differential and algebraic equations (DAEs). The proposed technique, based on the balanced realization theory (BRT), replaces the original model by one of reduced order, while preserving the physical meaning of retained state variables. Input and output variables of the model are selected in accordance with the goal of a particular study. State variables removed from the model are those that do not dominantly affect the nature of the phenomenon to be analyzed, as evidenced by the magnitude of the frequency response. The proposed technique provides insight into steps of the mathematical description of reduction for the considered phenomenon. In a given study, the number of state variables that can be eliminated depends on the power system model itself and on the required accuracy. Described approach is applied to two (benchmark and real-world) power systems.