A method for capturing optimal reclosing time of transient fault

Auto-reclosing is one of the main methods to improve the stability and reliability of power systems. For a transient fault, people generally believe that the earlier the reclosing time, the better the system stability will be. A new application of the transient energy function (TEF) is introduced in this paper to analyze the influence of reclosing time on power system stability and the results show that there exists an optimal reclosing time. The transient energy of the system is minimum when reclosing at the optimal time. Though the TEF of power systems is deduced from classical models, simulation results show that the optimal reclosing time calculated from TEF is also valid in complex model systems. Simulation results of a realistic system (46 generators and 230 buses) show that the method proposed in this paper is very effective for giving the correct optimal reclosing time of transient faults and that the oscillations of the generator angle and transmission line power can be largely damped when reclosing at that time