Method for on-line transient energy margin assessment

This paper presents some innovative techniques for enhancing the efficiency of hybrid methods in online fast transient energy margin (TEM) in transient stability assessment. For the evaluation of TEM along a post-fault trajectory, a transformed transient energy function is defined. Techniques such as the conservation principle of TEF, integration stopping criteria, location of `main potential energy peak', interpolation for critical clearing time and stability limit assessment are reported. These techniques have been tested on several test power systems with different system models. Test results show that the proposed techniques are promising. Example is given to show how to evaluate critical fault clearing time and transient stability parameter using interpolation approaches.