An improved network model for transmission expansion planning considering reactive power and network losses

The expansion plan obtained from a DC model based transmission expansion planning (TEP) model could be problematic in the AC network because the DC model is potentially inaccurate. However, solving TEP problems using the AC model is still extremely challenging. The motivation for this work is to develop a less relaxed network model, based on which more realistic TEP solutions are obtained. The proposed TEP model includes a linear representation of reactive power, off-nominal bus voltage magnitudes and network losses. Binary variables are added to avoid fictitious losses. Garver's 6-bus system is used to compare the proposed TEP model with the existing models. An iterative approach for considering the N-1 criterion during the planning process is developed and demonstrated on the IEEE 118-bus system. Simulation results indicate that the proposed TEP model provides a better approximation to the AC network and is applicable to large power system planning problems.