Evaluation of simplified flexibility evaluation tools using a unit commitment model

Different tools and methods have been proposed in the literature to assess the required flexibility resources and needs in a particular grid or geographical area. However, few of them are readily usable in long term energy planning models because they require small time steps and detailed data. In this paper, two candidate methods to address the flexibility issues in such models are evaluated. A unit commitment model developed at the JRC, DispaSET 2.0, is used as a test case for the different simplified flexibility assessment tools. The modelled geographical area is Belgium, using historical data for the demand and VRE curves and their day-ahead forecast. Different VRE penetration scenarios are simulated to evaluate the flexibility of the power system. The simplified assessment tools are then run with the same inputs. Results indicate significant discrepancies between the detailed Unit Commitment model and the simplified tools. The underlying reasons are described and suggestions are formulated to improve their accuracy.