N−1 security assessment incorporating the flexibility offered by dynamic line rating

With increasing shares of renewable energy sources (RES) and intensified electricity trading, the transmission system is operated closer to its limits. Dynamic line rating (DLR) can be used to obtain additional transmission capacity on existing lines by considering current meteorological factors. DLR is hence in general less conservative than nominal line rating (NLR). In this paper an approach on how to include DLR in a N-1 secure dispatch optimization is presented. The evolution of the conductor temperature is simulated and the power flow is then guided by constraints on the conductor temperature rather than by the traditional NLR setting the limit on power flow. Two approaches on N-1 security are described, where either a steady-state or a dynamic conductor temperature calculation is employed. The method is evaluated in case studies regarding RES integration, dispatch cost and computation time using historic load profiles and meteorological data.