Abstract:Flexible AC transmission systems (FACTS)devices can effectively optimize the distribution of power flow. Power flow entropy can be applied as a measure of load distribution. In this paper, a method is proposed to optimize the distribution of power flow with the coordination of multi-type FACTS devices and establishes the corresponding mathematical models. The modified group searcher optimization (GSO) algorithm is proposed, in which the angle search is combined with chaotic search model to avoid jumping into local optimization. Compared with the different optimal allocation of multi-FACTS devices, the optimal allocation of multi-FACTS devices isachieved under the economic constraints. The locations obtained by this method can achieve the purpose of bal-ancing power flow and enhancing the system perfor-mances. The simulations are demonstrated in an IEEE 118-bus power system with two classical types of FACTS,namely static var compensator (SVC) and thyristor con-trolled series Compensator (TCSC). The simulation results show that the proposed method is feasible and effective.