Load frequency control (LFC) scheme communicates from remote terminal units to control centre, followed by control centre action on the corresponding plant units. The conventional dedicated communication channels have constant time delay, while open communication channel, i.e. shared one has time‐varying delay. These delays degrade the dynamic performance or even lead to system instability. In an interconnected system, communications delays cannot be ignored and therefore the time delay is introduced in the area control error signal. In this study, a time delay‐dependent H _∞ ‐based non‐linear sliding mode controller for LFC scheme has been proposed for N area power system. The approach uses Lyapunov–Krasovskii functional based on time delay‐dependent stability criteria and linear matrix inequalities optimisation. Simulation studies are presented for two‐area LFC scheme against step and random step load disturbance and generation rate constraints. Comparison is also made with recently reported; two‐term controller design. The simulation results establish the superiority and applicability of the proposed design for LFC application. The results illustrate that the proposed scheme can effectively enhance the frequency stability via improving the damping of the system.

In this study, an observer based control strategy is proposed for load frequency control (LFC) scheme against cyber‐attack uncertainties. Most of research work focused on detection scheme or delay estimation scheme in presence of cyber‐attack vulnerabilities and paid less attention on design of counteractive robust control scheme for LFC problem. Thus, observer based control scheme is designed here and provides robust performance against unknown input attack uncertainty and communication time‐delay attack uncertainty. The generalized extended state observer (GESO) is used not only for state and disturbance estimation but also for disturbance rejection of the system. The said observer ensures accurate estimation of the actual states leading to convergence of estimation error to zero. So, the observer based linear quadratic regulator (LQR) is used to regulate the closed‐loop damping ratio against cyber‐attack uncertainty. In addition to fast response in terms of settling time and reduced over/undershoots, the proposed control scheme satisfactorily compensates the cyber‐attack uncertainties in power system cyber physical networks and also compared with existing traditional PI and PID controllers. The simulation results demonstrate the robustness in terms of stability and effectiveness in terms of system security with proposed controller when subjected to cyber‐attack uncertainties and load disturbances.

This study designs an effective mitigation control scheme for a class of attacks called resonance attacks on the power grids. Mainly in this attack, an enemy is able to disturb a stable power system via manipulation in rate of change of frequency (RCF). Thus, in countermeasures, a detection and mitigation control scheme propose using artificial neural network (ANN) observer-based sliding mode controller (SMC) in this study. Malicious resonance offensive uncertainties are estimated via ANN observer effectively. The estimated states and uncertainties via ANN observer are utilized as input in SMC design to select switching surface boundary limits. The asymptotic stability of proposed control scheme is analysed using the Lyapunov stability theorem. The presented control technique regulates rate of change of frequency within permissible limits with reduction in chattering and frequency oscillations even in presence of resonance offensive patterns. Detection and mitigation capability of proposed controller is illustrated by MATLAB simulations.