Active fault-tolerant control for load frequency control in multi-area power systems with physical faults and cyber attacks

Load frequency control (LFC) is an effective method to maintain frequency stability in power systems. With the large-scale application of wide-area measurement system (WAMS), impacts of unexpected physical faults and malicious cyber attacks on the frequency deviation damping performance of LFC systems cannot be ignored anymore. Different from the traditional robust-based design methods, which assume that the operating parameters vary within a small range, physical and cyber failures may cause the significant structural or parametric changes in LFC system. Hence, a system parameter-free active fault-tolerant control (AFTC) strategy for LFC is proposed. First, a bank containing a series of controllers is predesigned to stabilize all the possible operation scenarios. Second, a zero trial-and-error selection scheme, which does not depend on prior system parameters is well-designed to select the most matching controller. To enhance the fault-tolerant ability in case of unmodeled faulty situations, an expansion scheme without any prior faulty information is proposed. Finally, simulation results of a three-area-interconnected power system show that our proposed method can ensure the smooth transition of LFC system under physical/cyber failures, thereby the reliability of power grid operation can be enhanced.