This paper proposes a simplified algorithm to calculate the optimal power flow (OPF) in hybrid AC/DC grids with multi-terminal High Voltage Direct Current systems based on Voltage Source Converters (VSC-HVDC). The proposed algorithm makes it possible to solve OPF problems on hybrid AC/DC systems based on a previous large AC case to which several multi-terminal VSC-HVDC systems have been added. Each VSC is modelled as two generators with a coupling constraint; and the DC grids are modelled as notional AC grids, since, in per unit, the equations for a DC grid are a particular case of an AC grid with resistive lines and no reactive-power injections. Therefore, the solution can be found with the same tool used for the previous AC problem and a simple extension of the original case.
Keywords: VSC HVDC, HVDC transmission, multiterminal, optimal power flow, power systems.
Registration date: 2017-10-18