An OPF-based procedure for fast TTC analyses

Around the world the new competitive framework and the environmental opposition to the construction of new lines are driving transmission systems to operate closer and closer to their limits. On the other hand, network congestion becomes the main limitation to the power exchanges in the liberalized markets. A suitable calculation of the total transfer capability (TTC) and the analysis of its dependence on some system parameters are of primary importance both for an actual suitable operation of the electricity market and for an adequate planning of the network reinforcements. The main focus of this paper is the definition of a new procedure based on an advanced real power security constrained optimal power flow for the fast evaluation of TTC. Important byproducts of the optimization program are represented by the TTC sensitivities with respect to the thermal limits of the binding constraints on the transmission lines and to the allocation and the size of the new generation sites. The procedure has been employed for the assessment of the impact of the installation of new plants on the TTC between Italy and the neighboring UCTE countries and of the adequacy of the planned interconnection corridor reinforcement in forecasted scenarios at the year 2010.