Optimal α-Variable Model-Free Adaptive Barrier Function Fractional Order Nonlinear Sliding Mode Control for Four Area Interconnected Hybrid Power System With Nonlinearities oleh Omer Abbaker Ahmed Mohammed, Lingxi Peng, Gehad Abdullah Amran, Hussain AlSalman, Modawy Adam Ali Abdalla, Omar Alkawmani, Muhammad Mursil, Bassiouny Saleh