Synergistic mechanism for secure-economic-frequency regulation performance of hydropower Units: Dynamic load dispatch method with zonal constraints

Hydropower units are progressively critical for grid frequency stabilization amid large-scale renewable energy integration. However, under stringent power quality assessments, units undertaking rapid frequency regulation tasks beyond design specifications face escalating penalty pressures in power quality evaluations. Existing governor control optimization studies have improved individual unit regulation quality, yet lack coordinated optimization strategies for plant-level security-economy-frequency regulation performance. This gap complicates load dispatch alignment between second-level frequency response and minute-level allocation.To address this, we propose a full-head operating zone partitioning method for primary frequency regulation (PFR) performance, using the "Two Detailed Rules" metrics as benchmarks. By embedding zone classifications into objective functions or constraints, we develop a plant-level load dispatch model integrating PFR performance. Case studies from a Northwest China clean energy base, covering six scenarios, verify the model's accuracy and superiority across temporal scales, while revealing load variation impacts on PFR metrics during frequency disturbances.Results show the zone-constrained dispatch model improves generation efficiency by 3.54 % and reduces vibration by 37.33 %, fully meeting PFR assessment requirements. This work offers a theoretical and engineering decision-making tool for hydropower plant security and economic operation in electricity markets.