Assessing the Risk of Transmission Line Overloads in Power Grids with Stochastic Generation

The production of electrical energy from renewable sources has, in recent years, increased significantly with wind generation as the predominant technology. This development is expected to continue in the near future. However, the integration of such stochastic and intermittent power sources into the existing power system implies a higher ratio of non-dispatchable generation which, in turn, leads to less predictable and more volatile flows on the network. The intermittent nature poses a challenge for an adequate generation capacity planning, and the operational uncertainty of the time-varying load flow regime makes the anticipation of critical situations such as transmission line overloads highly complicated. This extended abstract presents a hybrid modeling and simulation approach with the objective of assessing the impact of intermittent generation on the probability of thermal line overloads and of analyzing the time sequences of subsequent cascading line outages. Thereby, the power flow dependent, dynamic line temperatures are explicitly modeled in time. In order to overcome the problem of the slow simulation speed coming along with the continuous integration of the heat balance equation, we apply a technique for the fast simulation of rare events, called RESTART (REpetitive Simulation Trials After Reaching Thresholds) on the present problem. The modeling framework is applied to the IEEE Reliability Test System 1996 whereas the effect of different stochastic power injection patterns on the line outage probability and on subsequent cascading failures are analyzed.