Enhancing Electric Grid Flexibility for the Integration of Variable Renewable Energy: Challenges, Innovations, and Future Directions. - Mohammed Saber Eltohamy; Muhayya Saad Muhayya Aldawsari; Amir Raouf Adly Sadek; Hossam Youssef Abdel-Hamid Hegazy; Ijaz Ahmed; Theyab R. Alsenani; Yunsu Kim 002; Mohamed Mostafa Ramadan Ahmed (IEEE Access, 2026)