Investigating the Consolidation of the Optimal Design of Distributed Energy Systems with Optimal Power Flow.

Distributed energy systems have the potential to minimise costly network upgrades while increasing the proportion of renewable energy generation in the electrical grid. However, the integration of DES into existing distribution networks warrants further research, as poorly designed DES can upset the delicate balances in these networks. Although optimisation models have been used widely in the literature to design DES, most of these have excluded nonlinear and nonconvex constraints associated with AC power flow and the distribution network. A few studies have attempted to consolidate DES with a standalone class of models known as Optimal Power Flow (OPF), which contain detailed constraints of the distribution network but exclude DES. These studies have often overlooked the different types of distribution network configurations, and do not provide comparisons with DES-only formulations. This study aims to address this gap by presenting an open-source optimisation model for DES design combined with a nonlinear OPF framework employing four solution methods, including two new bi-level methods which can influence the DES design. A low-voltage distribution network is used to obtain results and compare the efficacy of these methods. Results suggest that under certain network configurations and scenarios, a combined DES-OPF framework is essential as typical mixed-integer and linear formulations do not provide solutions that are compatible with network constraints. Similarly, current violations that have been previously reported in literature are not seen under certain configurations, highlighting the importance of including such detail in combined DES-OPF models.