Fig. 4From: Design of a 2-DOF-PID controller using an improved sine–cosine algorithm for load frequency control of a three-area system with nonlinearitiesTransient responses of frequency and tie-line power of all areas and convergence curves of the controllers for 2% SLD in area-1 and area-2 for 2-DOF PID, FOPIDF, and PID controllersBack to article page