Diagnosing Coordination Constraints in DER-Rich Power Systems: A Functional Framework for Architectural Compatibility

Rising penetration of distributed energy resources (DERs) distributes coordination-relevant capability, information, and constraints across power systems. This paper develops a functional framework for diagnosing whether coordination architectures remain compatible with these conditions. Coordination architecture allocates and connects Observation, Representation, Behavioural Selection, Behavioural Realization, Learning, and Adaptation. The framework is applied to a stylized CAISO-informed TSO–DSO–DER case and operationalized through capability relationships and hypotheses. A controlled IEEE 33-bus benchmark varies the representation of identical DER capability while holding the physical system and Selection rule constant. Nominal aggregation produces false-feasible selections in 58–71% of requests, whereas conservative representation eliminates infeasible selections but withholds usable flexibility. A network-feasible representation eliminates false-feasible selections under unchanged conditions while reducing unnecessary restriction; after a 10% load change, 16% of selections using the unchanged representation become infeasible. The results attribute a Selection consequence to Representation distortion and show that representational adequacy is problem-dependent. The benchmark provides controlled support for function-specific diagnosis and problem-relative architectural compatibility, without validating the complete framework or claiming superiority of any architectural form. Preprint status: This is the author's original manuscript submitted to Electric Power Systems Research on 7 September 2026 (manuscript EPSR-D-26-08761). It has not yet undergone peer review. Supporting research: Numerical benchmark, source code, configurations, and reproducibility materials: https://doi.org/10.5281/zenodo.21945173.