Load frequency control for cyber-physical microgrid via a relaxed quadratic convex framework

In microgrid system, all distributed generation (DG) source are operated and controlled cooperatively to ensure a stable operation with a desirable frequency. For this purpose, the central load frequency controller is generally implemented together with an open communication network which causes time delay. This paper focuses on load frequency control (LFC) for cyber-physical microgrid with interval time-varying delay. First, we propose the cyber-physical system modeling approach for the microgrid. Second, a parameter-adjustable quadratic convex framework is developed, which relaxes the quadratic function negative-determination conditions. Then, the new delay-dependent stability criteria of cyber-physical LFC microgrid are obtained by using the augmented LKF, mixed convex combination techniques together with the second-order B-L inequality, which reduce the conservatism. Finally, case studies demonstrate the merits of the proposed scheme over existing methods.