A new control scheme for PID load frequency controller of single-area and multi-area power systems

► A new control structure is for LFC single-area and multi-area power systems. ► Relay feedback identification method is used for system dynamics. ► Better damping for frequency and tie-line power deviations achieved. ► The controller gives robust performances against parameter uncertainties. ► Kharitonov's theorem is used for the robustness analysis.