In response to global energy demand, the enhancement of transport capacity in electrical transmission lines is deemed essential. The conventional method of constructing new lines is considered costly, time-consuming, and subject to constraints imposed by economic and environmental factors. Among various emerging solutions aimed at enhancing the passive capacity of transmission lines, the technology of flexible AC transmission systems (FACTS) has been demonstrated to be highly effective. This paper proposes the utilization of the static synchronous series compensator (SSSC), a closed-loop control system and a type of FACTS, to alleviate the overloading of transmission lines in the Syrian electrical network. To achieve this objective, the network is first modeled to identify the overloaded transmission lines. Subsequently, the particle swarm optimization (PSO) algorithm is employed for the optimal sizing and allocation of SSSCs within the network. The findings showcase the significant reduction in loads on critically overloaded transmission lines subsequent to the successful implementation of SSSC devices. This serves to validate the improvements made to the existing infrastructure of the Syrian electrical network’s transmission lines, without necessitating the construction of new transmission lines.