An MILP Model for Evaluating the Optimal Operation and Flexibility Potential of End-Users

It is expected that end-users from all sectors should participate in providing system flexibility, as variable renewable energy is increasingly integrated into electricity systems. The ability of end-users to shift their electricity profiles has considerable potentials and can serve many purposes, e.g. to curb the peak load or to increase self-consumption. However, evaluation methods designed for flexibility from conventional power plants may be inadequate for flexibility from end-users due to the diverse constraints of underlying processes and limitations related to individual needs. This work presents a comprehensive and modular flexibility model developed from common operational characteristics of flexible processes as an alternativemethod. The model is applied to two examples: First, the operation of a combined heat-and-power plant including input and output storage is optimized with the objective to increase profits from electricity sales on the spot market. Second, a steel rod production line consisting of melting, casting, and milling processes is scheduled so that operating costs, including peak power costs, are minimized. Moreover, potentials of flexibility as external services and related costs are analysed. In this paper, the model is used to calculate the optimal costs (e), time-dependent flexibility potentials (kWh) and costs of flexibility provision (e/kWh). Thus, the adaptability and versatility of the model are demonstrated. As a modelling template, the model can ease the efforts of stakeholders in the characterization and evaluation of various flexible processes, especially those from small and medium-sized users.