A Manta Ray Forging Algorithm Solution for Practical Reactive Power Optimization Problem Hong Jiang Wang1, Thi Kien Dao1, Van Dinh Vu2, Truong Giang Ngo3, Thi Xuan Huong Nguyen4, Trong The Nguyen4 1Fujian Provincial Key Laboratory of Big Data Mining and Applications, Fujian University of Technology, Fuzhou, China; 2Information Technology Faculty, Electric Power University, Hanoi, Vietnam; 3Faculty of Computer Science and Engineering, Thuyloi University, Hanoi, Vietnam; 4Haiphong University of Ma[.]