Ever increasing exploitation of the existing electric systems and problems of the construction of new transmission lines due to technical limitations, environmental and economic considerations make designers and engineers to assure the use of flexible alternating current transmission systems (FACTS). One of the most effective members of the FACTS devices is static synchronous compensator (STATCOM) which is parallel with the network. Parallel controllers of FACTS devices by injecting a current into the network, control the network parameters such as reactive power and bus voltage. In this paper, the influence of the PI and PID controls on active and reactive powers...