Abstract--In power system operation, maintaining power flow solvability is important. In the recent deregulated environment, uncertainty has become more prevalent in power systems because of diverse power transactions and benefit-based operational schemes. Thus, in the present and future power industry, there may be more unsolvable cases than there were in the past integrated power industry. This paper presents a methodology to determine the adequate reactive power compensation for restoring power flow solvability in the unsolvable severe contingencies. To analyze power flow solvability, a continuation power flow tool parameterizing branch parameters of contingencies is applied. In solvable cases, the adequate locations of the additional reactive power injection are determined by sensitivity analysis based on the normal vector at the nose point of the independent parameter vs. V curves, constructed by the continuation power flow tool. The effectiveness of the sensitivity information is verified by comparing the amount of reactive power compensation at each location. In a case study, the proposed algorithm is applied to the Korea Electric Power Corporation (KEPCO) Systems.
