Congestion management through rotor stress controlled optimal transmission switching

Security constrained optimal transmission switching (SC-OTS) can be an essential part of future smart grids with flexible topologies. Transmission switching, however, can have adverse impact on generators because of creating excessive torque on their rotor shafts. In this study, SC-OTS as an effective tool is applied to relieve congestion while considering AC constraints and generator rotor shaft impact caused by switching. As opposed to previously used simplified models based on standing phase angle, this study utilises dynamic response of generators to accurately calculate the actual stresses on rotors because of switching. In addition, network N-1 security criterion is taken into account. In the proposed model, OTS actions are obtained through a bi-level process. In the upper level, OTS set is determined and the applicability of each action is checked in the lower level. The proposed methodology leads to a mixed integer non-linear programming problem, which is formulated and solved based on Benders decomposition. Test results for the IEEE 57 and 118-bus systems illustrate the effectiveness of the method in removing congestion while ensuring that destructive switching manoeuvres are avoided.