Impact of Capacity Calculation Methods on Grid Operation Studies: Flow Based versus Net Transfer Capacity

In grid operation studies of the European Power System, including electricity market and subsequent transmission grid operation simulation, the underlying capacity calculation methodology for cross-border exchange influences complexity significantly. Since the complexity of modeling the flow based method is much higher, the question arises what impact using the less complex net tranfer capacity approach has on the grid operation results. To contribute to this question, this paper describes both methods and gives an overview about the overall power system studies toolchain. Comparing two annual simulation runs based on a 2030's scenario indicates that the capacity calculation methodology in power system studies has implications for both, market and grid results. Spatially aggregated grid results in the flow based region show only slight differences. Spatially detailed grid results, however, in some bidding zones show significant differences. Thus, the net transfer capacity approach can be a suitable simplification for grid operation studies to obtain comparable high level grid results with less complexity. As soon as spatially detailed results are in focus, however, significant differences to the flow based method are to be expected.