Large-scale integration of renewable power (RP) into a power system (PS) decreases the inertia of the PS which generates a high rate of change of frequency (ROCOF) and frequency instability in the PS. A multi-area PS integrating RP has to overcome even more complex frequency instability issues while delivering power to the load. The frequency control mechanism of such inertia-less or low-inertia multi-area systems is supported by additional synthetic inertia (SI) control scheme for enhancement of system inertia and maintenance of frequency stability. In this paper, super-capacitor (SC) energy storages and electric vehicles (EV) have been used to support the frequency regulation of a multi-area PS with high renewable RP penetration. The proposed SI control scheme includes two SI control loops - an SC bank forms the SC control loop and charging/discharging EVs forms the EV control loop. The designed fractional order (FO) controllers along with both inertia and damping properties have been considered in the SI control loops. Genetic algorithm (GA) has been used for optimising the parameters of the proposed SI control system. The performance of the proposed 2-loop (SC + EV) SI control strategy has been compared to other SI control techniques for different weather conditions and variation in load. The robustness of the proposed frequency regulation scheme has been verified by comparing the dynamic response of the multi-area PS for different controllers for randomly varying loads and weather conditions, changing system parameters, and different operating conditions. The efficiency of the proposed SI control technique has also been verified in real-time using Opal-RT.