In this paper, a distributed optimal power flow (OPF) for the AC/DC hybrid grid, composed of the AC grid, renewable energy system (RES), and voltage source converter (VSC)-based multi-terminal DC (MTDC) grid, is presented. Firstly, we apply a series of linear approximations/convex relaxations to construct a mixed-integer convex AC/DC OPF model. To address the uncertainties from RESs, we then illustrate scenario-oriented decision making for the constructed AC/DC OPF model. Additionally, we verify that considering all possible scenarios can be replaced by a small set of extreme scenarios if the OPF model is (mixed-integer) convex. Furthermore, we develop a scenario-oriented multi-cut generalized Benders decomposition to achieve more efficient distributed problem solving for the constructed AC/DC OPF model. Finally, numerical results are provided to validate the effectiveness of our constructed AC/DC OPF model and our developed distributed problem-solving approach.

This study presents the initialisation of a hybrid alternating current/direct current (AC/DC) power system to determine the operation point around which the system is linearised as a starting point for an electromagnetic or harmonic stability analysis. To this end, each AC or DC power system component is modelled in the Fourier transform domain and further adjusted to a simplified representation compatible with a power flow formulation. The study also presents how voltage source converter (VSC) high-voltage DC-based systems can be analysed when the different VSC controls are applied. The result of the power flow solution is then used for the power converters’ initialisation.