This book reports an application of Multi-objective Evolutionary algorithm for solving the security enhancement problem. Generation rescheduling and adjustment of TCSC &SVC are used to alleviate the line overload. The probable locations of TCSC &SVC are pre-selected based on Participation Factor Index(PFI) which ranks the system branches according to their severity. The security enhancement problem is formulated as a multi-objective optimization problem with optimal allocation of TCSC &SVC and minimization of control variable adjustment cost as objectives. Non-dominated sorting algorithm is applied to solve this Generation Cost optimization.