Bound Estimates of the Severity of Line Outages in Power System Contingency Analysis and Ranking

The effect of line outages on the real power flows of a system is analyzed using the DC load flow model. It is shown that the effect of the out4ge of line jk on the power flow of an arbitrary line lm can be bounded above and below by a series of progressively tighter values which in the limit correspond to the exact DC load flow solution. The calculation of these bound estimates on the contingency line flows is progressively more computationally demanding as the limits tighten, however, the simple to compute bounds, although more conservative, still serve to filter out a large portion of the non-critical contingencies. The remaining few potentially critical outages can then be ranked and analyzed through the full DC load flow.