Critical-cluster identification in transient stability studies [of power systems]

A method is proposed for identifying the critical cluster of machines, i.e. the machines responsible for loss of synchronism in a power system following a large disturbance. It is based on the conjecture that the loss of synchronism condition can be recognised by, first, considering `near-critically cleared trajectories´ of the machines and, secondly, observing how they are organised near the system´s unstable equilibrium point. Examples are given using the IEEE test system to illustrate the essential features: reliability in correctly identifying the critical clusters; robustness with respect to its capacity to do so under very stringent conditions; and effectiveness concerning its ability to identify automatically critical clusters of any size, i.e. irrespective of the number of machines that they contain