Optimal reclosure time for improving power-system dynamic behaviour

Transmission-line reclosure is an efficient structural action for improving dynamic behaviour of electrical power systems. Attractive techniques have been proposed for calculating the optimal reclosure time. While these techniques are based on energy considerations, the paper presents a novel method for computing the optimal reclosure time of a transmission line, based on optimal control strategies for switched dynamic systems. This technique allows use of high-order modelling, including control-system and relay action. By means of numerical simulations performed over a 39-bus 10-machine test system, the effectiveness of the proposed strategy is shown in terms of improvement in damping oscillations and increased system stability. A comparison with other methods is also presented.