CRITICAL CASES IN THE OPTIMAL POWER-FLOW

This paper presents a systematic analysis of the main reasons for the failure of solution algorithms in the general non-linear optimal power flow (OFF) problem. It defines the concept of critical and non-critic al OFF problems and identifies and categorizes the main types of such cases. In essence, a non-critical case is one where a small variation in a parameter leads to a small change in the optimum solution. Altern atively, critical cases are such that a small variation in a problem p arameter leads to either the loss of local optimality or feasibility. Both of these can result in a sharp discontinuity in the solution. Num erical and theoretical examples illustrate each of these cases.