Abstract: The grid topology is fixed in the traditional unit commitment,regardless of the transmission line active breaking.In order to solve the problem of transmission line congestion caused by unit commitment,this paper takes into account the change of power grid topology in the traditional unit commitment model,and establishes unit commitment model which takes active optimal transmission switching into consideration.The model includes network security constraint.By introducing Big-M method,the active optimal transmission switching model is transformed into the mixed integer linear programming formulation.In order to speed up the solution of the model,this paper uses genetic algorithm combined with mixed integer linear programming.This paper not only can give the unit commitment schemes at each time,but also get the optimal network topology of each period.An example of a modified IEEE-RTS 24 nodes indicates that the combination of units commitment taking into account active optimal transmission switching can be more effective in reducing the overall cost of the system.

Key words: unit commitment, network topology, network security constraint, active optimal transmission switching