Contingency screening; Voltage stability; Security enhancement
This paper presents an efficient one step look-ahead approach for post-contingency loadability limit analysis and its enhancement in critical cases. This is achieved by using steady state analysis tool judiciously within its limitations. The proposed approach does not require
any computation of post-contingency distance or margin to the loadability limit for screening non-critical contingencies. In the new approach, the possibility of occurrence of critical loading earlier than the predicted load at next step corresponding to monitoring and
control rescheduling stage is examined after each contingency at base case. Only a load flow convergence check is required for this purpose.In critical cases where loadability limit is insufficient, strategies for post-contingency rescheduling of controls at base-case loading are devised such that the deviation from the base-case control schedule is minimum and the loadability limit is pushed beyond the next predicted load step. Results for a sample test system have been obtained to demonstrate the suitability of the proposed algorithm.