Hybrid AC/DC Optimal Power Flow Modelling Approach for Coordination in Flexibility Market

To meet new challenges in the transmission and distribution grid, it becomes necessary to implement a flexibility markets mechanism. This paper proposes a framework based on optimal power flow for coordination of flexibility exchange between transmission and distribution grid. The acquiring flexibility assets can be applied effectively in response to possible grid challenges in different electricity grid levels. The proposed power flow approach is formulated as a hybrid AC/DC optimal power flow (AC/DC-OPF) model. This model consists of two different power flow methods. For the distribution grid, a second-order cone AC optimal power flow (SOC-ACOPF) method is formulated. For the transmission grid, a DC optimal power flow (DCOPF) method is applied. This approach also incorporates scenario-based and multi-period modeling, optimizing flexibility usage for a predefined period. The optimization is based on power demand, grid constraints, cost minimization, and operational criteria for distributed energy resources. The results presented in this paper are valuable for creating and implementing an adequate flexibility exchange mechanism between TSO and DSO.