Optimal Integration of Phase Shifter as Power Flow Controllers in Transmission Network Expansion

Phase shifting transformers are devices that allow transmission system operators to control active power flow, and their use has increased over the last years. This paper proposes a mathematical optimization model for transmission network expansion considering the incorporation of phase shifting transformers. The performance of the proposed model was analyzed using the 9-bus IEEE test system and considering an annual load demand growth of 5%. Simulation results indicate that lower investment costs are needed if phase shifting transformers are considered in the optimization model compared to the investment costs when only transmission lines are considered in the optimization model. Furthermore, the results indicate that if neither transmission lines nor phase shifting transformers are incorporated into the test system over the planning period, the total load demand cannot be supplied.