Role-Aware Hierarchical Primary Frequency Regulation of Heterogeneous Source–Grid–Load Energy Storage System

With high renewable penetration, primary frequency regulation (PFR) in low-inertia power systems faces a critical challenge of balancing frequency security with sustainable energy storage system (ESS) utilization. Existing ESS-based PFR studies mainly focus on single-sided resource support or homogeneous modeling, which cannot address the cross-side coordination demands arising from heterogeneous ESS on the source, grid, and load sides. This paper extends ESS-based PFR to a synergistic scenario involving heterogeneous three-sided ESS. A unified modeling framework is established, explicitly incorporating differences in capacity, functional roles, participation priority, and security boundaries. Based on this, a hierarchical decoupling control structure is proposed, separating system-level frequency regulation from side-level energy coordination. The upper level uses a low-dimensional equivalent representation to reduce the optimization burden from modeling numerous ESS units, while the lower level achieves complementary advantages and orderly task allocation among the three sides through differentiated coordination. Simulations show that the method maintains system frequency performance while achieving rational PFR responsibility allocation across source-, grid-, and load-side ESS, effectively leveraging multi-sided heterogeneous ESS for synergistic regulation, and verifying the hierarchical decoupling framework as an effective approach for coordinating multi-side energy storage.