Economic Benefit Comparison of D-FACTS and FACTS in Transmission Networks with Uncertainties

Distributed flexible AC transmission systems (D-FACTS) has become increasingly popular in recent years. Among all types of D-FACTS devices, variable-impedance D-FACTS is the most cost-effective. However, integration of these devices within an optimal power flow problem introduces nonlinearities that are computationally challenging. In this study, a computationally efficient stochastic optimization model is proposed to optimally allocate variable-impedance D-FACTS considering the randomness of wind power output and load variation. The optimal locations and economic benefits of D-FACTS are compared with those of conventional FACTS. The results show that D-FACTS devices are more cost-effective than conventional FACTS, considering complex operation conditions in a transmission network. The economic benefits will increase if periodical redeployment of D-FACTS is allowed.