Security-constrained unit commitment is studied by taking into account multiple correlated wind sources and the deliverability of operating reserves in a reserve zone. A power transfer margin for each transmission line is incorporated into the unit commitment problem, so as to mitigate possible congestions caused by uncertain and non-dispatchable wind power. Specifically, the power transfer margins of transmission lines are determined by utilizing the probabilistic information of multi-locational wind power generations, and by considering credible line-outage contingencies. The power transfer margins collectively guarantee that congested operating conditions occur with a reduced probability, and thus provide a new approach to the efficient management of intra-zonal congestions. The effectiveness of the proposed approach is verified through case studies on IEEE RTS-96, with comparisons to unit commitment with conventional reserve zone management.