Further Results on Stability Analysis of Load Frequency Control with Time Delays in both Feedback and Forward Channels

In the load frequency control (LFC) system that operates within open communication networks, time delays inherently arise from both the forward and backward channels of the control loop. Conventionally, the feedback delay and the forward delay are either modeled separately or aggregated into a single delay. In this paper, further results show that these two modeling approaches are indeed equivalent for the eigen-analysis. Besides, an exploration is conducted to elucidate the relationship between the delay margin for the two separately modeled delays (2-DM) and that for the single aggregated delay (1-DM). The results show that the 1-DM is the sum of the elements in the 2-DM. Furthermore, the effects of controller gains on these two kinds of delay margins are also investigated. Finally, case studies are carried out to verify the effectiveness of the obtained results.