A Research On Distributed Power Flow For AC/DC Interconnected Grid Based On Asynchronous Iteration

The contradiction between AC/DC interconnected power systems and independent calculation mode adopted by regional control centers brings in various drawbacks to the analysis and monitoring of a power network. To solve these problems, a distributed power flow algorithm for AC/DC interconnected power grid is proposed. The method is based on asynchronous iteration mode. The algorithm applies to two-terminal HVDC transmission systems taken as tie lines. A DC line in modeled at the two terminal subsystems. Sequential method for AC/DC power flow calculation is used as the interior iteration. During the exterior iterations, DC line is equivalent to AC line which is used to construct fix-point iteration about boundary state variable; the equivalent injection power on the boundary buses is modified gradually to obtain a power flow result with that for whole system. Based on the method, the adjustment of convertor transformer's tap changer is taken into account in the distributed power flow. The experimental results of IEEE standard systems which are extended to AC/DC power system indicate that the algorithm is accurate.