Stability Analysis of Sampled-Data Load Frequency Control Systems With Multiple Delays

The load frequency control (LFC) system equipped with communication networks includes both sampled-data and time-delay characteristics. How to consider both characteristics effectively in stability analysis is of great importance to obtain accurate results. In this brief, we investigate the delay-dependent stability of sampled-data systems with multiple delays by separately considering the effects of sampling and delays. We first build a discrete-time model for an LFC system with both conventional units and energy storage systems, where the effect of time-varying delays is modeled as matrix uncertainty. Based on this model, we propose a stability criterion for delay margin computation using the region-division technique. A heuristic algorithm is further developed to enhance the computational efficiency and accuracy of the proposed criterion. Case studies are carried out to show the effectiveness and advantages of the proposed method.