Boundary properties of the BCU method for power system transient stability assessment

The BCU method has been confirmed as an important on-line tool for direct transient stability assessment of power systems. The boundary property, which guarantees the controlling UEP of the original model and that of the reduced-state model, is a key issue in the BCU method. Instead of one-parameter transversality conditions proposed earlier, analytical results on the boundary property will be explored. We have applied the self-indexing energy function and the structural stability to analyze boundary properties of simple power systems. We have shown that, under certain mild conditions, the original system and the reduced-state system share the same UEPs on stability boundaries. Numerical studies confirm theoretical developments.