Fractional order PID controller for load frequency control in a deregulated hybrid power system using Aquila Optimization oleh Deepak Kumar Gupta, Geetanjali Dei, Ankit Kumar Soni, Amitkumar V. Jha, Bhargav Appasani, Nicu Bizon, Avireni Srinivasulu, Philibert Nsengiyumva