Quantification of electrical system flexibility by local multi-energy systems: Impact of the system design and component interdependencies

Multi-energy systems (MES) providing electrical flexibility will be essential for low-carbon power grids. With the aim of embedding flexibility provision into the design phase of local MES, the presented framework proposes a quantitative assessment of how the sizing of individual and interdependent components affects technical flexibility. It identifies key components that either enhance or reduce the flexibility of MES. The framework includes a sensitivity analysis that provides valuable technical insights, such as a deeper understanding of limiting factors and interdependencies between components across energy vectors. Moreover, flexibility is quantified over multiple time steps in relation to a predetermined reference schedule, which is particularly important for energy systems that must submit their planned schedule in advance, thus ensuring constant flexibility provision for a specified duration. The adopted case studies, which use a residential building and a local energy community, underpin the capabilities of the proposed framework and its applicability to energy systems with internal network constraints. One of the key findings is that the coupled flexibility from the heat vector significantly increases active power flexibility, i.e., the range of increase and decrease in its active power during operation. This anchors heat pumps as a linchpin coupling component between electricity and heat in MES. Furthermore, the interdependence between the maximum thermal output of the heat pump and the thermal capacity of the hot water storage tank was quantified by a linear threshold relation, beyond which increasing the size of the heat pump does not improve system flexibility.