Seconds-scale renewable AGC security control considering multi-level transmission section constraints

With the increasing penetration of renewable energy, fluctuations of non-AGC renewable stations and load disturbances may cause security-boundary violations in multi-level transmission sections. This paper proposes a seconds-scale renewable AGC security-control method that integrates DNN-based fast state estimation, PTDF-based section-to-station sensitivity analysis, and quadratic-programming-based command optimization. The method redistributes AGC commands within a 4-s rolling cycle while coordinating transmission-section security, 15-min dispatch tracking, and renewable energy accommodation. Tests on the IEEE 118-bus system show that the active- and reactive-power relative estimation errors remain below 3% when the measurement-noise level is increased to three times its baseline value. In the baseline renewable energy export scenario, the proposed method reduces the control-boundary violation duration from 448 s to 0 s and the maximum boundary exceedance from 52.754 MW to 0 MW, while maintaining a renewable energy accommodation rate of 92.596%. Across ten operating scenarios, the method prevents physical overload in all cases and achieves accommodation rates of 90.447%–98.388%. These results demonstrate its effectiveness and computational feasibility for seconds-scale coordinated security control of multi-level renewable energy export sections.