There is a great resolution calling for smart grids in recent years. Introduction of new technologies, that make the network flexible and controllable, is a main part of smart grid concept and a key factor to its success. Transmission network as a part of system network has drawn less attention. Transmission switching as a transmission service can release us from load shedding and remove the constraints’ violations. In addition to removing the congestion and decreasing the system cost, transmission switching may damage generating units due to transient states in instance of reconfiguration. Therefore, in optimal transmission switching, the system security, practical limitations and possible damages should be considered. Considering dynamic constraints in proposed model avoid the occurrence of transient instability when opening the line in transmission switching action. A network reduction method based on modified Jacobean AC Newton-Raphson technique power flow considering switchable line in technique is used for speeding up the calculation, efficiency and simplicity. An approach for selecting the best lines in switching operation in the network is proposed. Based upon this approach, the lines with the highest effect on cost reduction are considered as the candidate switchable line. To investigate the efficiency of the proposed strategy IEEE 57 bus test system is studied.
