Analytical Computation of the Sensitivity Coefficients in Hybrid AC/DC Networks

In this paper, we present a model for the analytical computation of the power flow sensitivity coefficients (SCs) for hybrid AC/DC networks. The SCs are defined as the partial derivates of the nodal voltages with respect to the active and reactive power injections and are used in the literature to model the grid constraints in a linear way (e.g. in real-time grid-aware control applications). The proposed method is inspired by an existing SC computation process proposed for AC networks and here suitably extended to include both the DC grid and the relevant AC/DC Interfacing Converters (ICs). The ICs can operate under different control modes i.e. voltage or power. Additionally, the model can compute the SCs for three-phase networks subjected to unbalanced loading conditions. The proposed method is numerically validated on a 26-node hybrid AC/DC microgrid and on a multiterminal HVDC network that links two asynchronous AC transmission grids. Furthermore, we provide a formal proof regarding the uniqueness of the proposed SCs computational model for hybrid AC/DC networks.