Multiple contingency selection for transmission reliability and transfer capability studies

This paper develops a multiple contingency selection procedure that can identify the single contingencies that cause thermal stress on the same branch or branches and, thereby, produce critical multiple contingences. This multiple contingency selection procedure is required if enumerative transmission reliability is to be successfully applied since all critical single and multiple contingences can be identified without excessive computation or false alarm or misclassification problems. The multiple contingency selection is accomplished by determining a list of contingencies for each branch that have: apparent power flows that exceed {alpha} {times} 100% of the thermal limit and apparent power flow changes that exceed {beta} {times} 100% of the thermal limit. A branch contingency measure is used to rank these single contingencies. Combination of the single contingencies taken from any branch's list of contingencies would produce multiple critical contingences with thermal overloads on that branch assuming superposition holds. The BOUNSM computer program that provides the information for the enumerative transmission reliability program also provides the information required to perform a transfer capability study. A monitored branch measure, which is the sum of the branch contingency measures for a particular branch, would identify the branches, paths, and interfaces that are most insecure for anmore » anticipated transfer and must be specified to run a transfer capability study. The combination of branch's list of contingencies for each of these branches, paths, and interfaces would be the list of contingencies that needs to be specified to perform a transfer capability study.« less