Multi-Period Hybrid AC/DC-OPF Model for Flexibility Market Clearing With Seamless TSO-DSO Coordination

Unlocking flexibility assets from the consumer side and developing a well-functioning flexibility market (FM) is crucial to address the oncoming challenges in the EU power grid. In these conditions, the coordination between distribution system operators (DSOs) and transmission system operators (TSOs) remains a critical task for optimally harvesting flexibility services. For that reason, this paper focuses on investigating the instruments for FM market design and modelling, which ensures proper TSO-DSO coordination. First, the paper introduces the scheme and strategy for FM operation and coordination in Norwegian conditions. After, the multi-period hybrid AC/DC-OPF model for FM modelling is presented. This model combines optimal power flow (OPF) methods consisting of a second-order cone (SOC)-ACOPF, which is applied for the distribution grid and DC-OPF for the transmission grid. The model was validated and tested based on grid configurations from existing projects, where it showed high accuracy and applicability. Finally, an example of solving grid challenges in a distribution grid with the help of flexibility services was presented. The outcomes of this paper propose valuable tools for establishing an effective flexibility exchange mechanism between TSO and DSO.