**6. Conclusions**

Congestion managemen<sup>t</sup> is one of the main challenges of power system optimization. Flexible AC Transmission System (FACTS) devices, such as TCSCs, can be used to manage line congestion with controlling the power flow of the grids. On the other hand, due to the high investment costs of FACTS device installation, determining their optimal locations is very important. In this paper, for the first time, power loss reduction, congestion management, and determination of the power line compensation rates are considered, to optimally allocate TCSCs and their susceptance values. The Jacobian sensitivity approach and AC load flow are used for line congestion evaluations. Then, the Multi-Objective Genetic Algorithm (MOGA) was applied to determine the optimal locations and susceptance values of TCSCs. The obtained results show that the optimal allocation and compensation rate of one TCSC can improve power loss and congestion indices. Additionally, the optimal allocation and compensation rates of two TCSCs show that increasing the number of TCSCs results in a slight power loss reduction and an improvement of the congestion index. Meanwhile, the obtained results are compared with those from different algorithms, such as the multi-objective Particle Swarm Optimization (PSO) algorithm, Differential Evolution (DE) algorithm, and Mixed-Integer Non-Linear Program (MINLP) technique, to evaluate the superiority of the proposed method—in terms of fast convergence and high accuracy—over the other heuristic methods. It is noted that the proposed method is a fast and accurate method that can be used for power system operation and planning studies.

**Author Contributions:** F.M. was responsible for methodology, collecting resources, data analysis, writing—original draft preparation, supervision, and writing—review and editing. T.-T.N. was responsible for writing—review and editing. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
