Unlock the Inter-Area Inertia Flexibility: An Enhanced Emergency Frequency Response Scheme for HVDC-Interconnected Systems with Uncertainty

Due to the increasing penetration of variable renewable energy (VRE), the shortage of power system inertia has brought significant challenges to frequency stability in the High Voltage Direct Current (HVDC) connected systems. To further incentivize the inter-area frequency response resources by leveraging the flexibility of HVDC, we propose an enhanced emergency frequency response (EEFR) scheme, and upon that an inter-area inertial market is designed. Our scheme focuses on resilience against low-probability extreme events, the DC converters will instantly increase the electromagnetic power to compensate for the sudden power imbalance, thereby apportioning the frequency deviation systematically by enabling inter-area inertia delivery among areas. For the first time, we innovatively embed the proposed EEFR scheme into the chanceconstrained unit commitment (CCUC) problem by proving the model's convexity and deriving its dual form to obtain the Benders feasibility cuts. To solve the model in a distributed way with privacy concerns, we devise an improved alternating direction method of multipliers (ADMM) algorithm to extend our model into separable problems with convex constraints. Through the results on test systems, we validate that the EEFR-embedded CCUC model is more cost-efficient with enhanced resilience. The resulting dispatch and pricing decisions are efficient and constitute a competitive equilibrium.