The intent of this paper assimilates the issues of automatic generation control (AGC) of a two-area power system entailing five numbers of renewable as well as conventional sources such as thermal unit, hydro unit, wind unit, diesel unit, and photovoltaic (PV) unit. To make the proposed model more realistic, some non-linearities like boiler dynamics, governor dead band (GDB), and generation rate limit (GRC) are inducted into their concerned sources. The frequency stability of the system is enhanced by assuaging the transient indices like undershoot, overshoot, rise time, and settling time by employing two degrees of freedom (2-DOF) based fractional order (FO) cascaded controller incorporating with derivative filter (N) named 2-DOF-FOPIDN-FOPDN controller. The proposed controller along with 2-DOF-PIDN-PDN, and PID controllers are designed by endorsing selfish herd optimization technique (SHOT). The performance of the proposed controller is corroborated by comparing the performance exhibited by 2-DOF-PIDN-PDN, and PID controllers. Besides this, the know-how of the recommended controller is evaluated and investigated against solar power variation, load perturbation, and system's parameter deviation which confers the robustness of the controller is conceived.