Investigation of the performance of noDal and zonal Entso-E transmission system models in the context of large-scale integration of renewables

This paper focuses on the comparison of results obtained from a market and power flow simulation using an aggregated zonal and a detailed nodal model of the European transmission system. Both system representations are created based on a common data set at the Technical University of Munich. The zonal model incorporates an accurate representation of the power plant fleet alongside an aggregated network model, whereas the nodal model utilizes a detailed representation of substations and transmission line connections. A procedure is developed in order to facilitate the model comparison: a power dispatch violation variable of high cost is introduced to the DC optimal power flow formulation allowing a redispatch when transmission line flow limits are violated. It is shown that the zonal model generally produces feasible dispatch results (i.e. minimal redispatch and line overloading is observed in the subsequent nodal model calculation). However, it is discovered that the zonal aggregation process leads to significant deviations between the regional power flows in the two models. It is noted that the meshing of internal grids has a large influence on the regional power flow results.