Sampled-Data Automatic Generation Control with Delay-Dependent Intervals for Heterogeneous Resources

Emerging flexible resources have been integrated into automatic generation control (AGC) systems to mitigate the increasingly severe power disturbances caused by the growing penetration of renewable energy sources. These flexible AGC resources exhibit significantly different control characteristics compared to traditional thermal generators (TGs). Both academics and real-world independent system operators have carefully considered the fast-ramping capabilities of flexible resources, adapting AGC strategies accordingly. However, the differences in response delays between TGs and flexible resources have received less attention. This paper emphasizes that these response delay differences also necessitate corresponding modifications to AGC strategies to reduce the risk of frequency oscillations and improve frequency control performance. First, a practical sampled-data AGC dispatch strategy with delay-dependent intervals is proposed to better coordinate AGC resources with varying response delays. Second, a small-signal stability criterion under the proposed AGC dispatch method is derived to ensure frequency stability theoretically. Next, the time-delay stability margins of the proposed method are analyzed using the derived stability criterion and shown to be broader than those of commonly used AGC dispatch methods. Finally, time-domain simulations further validate the superiority of the proposed method.