Inferences from Numerical Model Reduction & Aggregation of Power-system Dynamics Featuring Primary & Secondary Control

Power systems feature significant complexity in constitution and function of individual resources, their interconnection, and the spread of timescales for their operation and control. While power-system model reduction and aggregation have long simplified simulations, analysis, and design, several traditional assumptions and practices may not be justified in future grids. This work considers a hierarchical architecture with distinct dynamics at the primary- and secondary-control levels as a baseline to address several questions pertaining to model reduction and aggregation including: the role of homogeneity of parameters, number of balancing areas for secondary control, and relative strengths of interconnections. Simulation results for a modified IEEE 39-bus network are presented to draw inferences for model reduction pursued via balanced truncation and aggregation of frequency dynamics.