Power flow partitioning is a topic of interest for European transmission system operators because of the increasing amount of Unscheduled Flows, which can cause congestions. Unscheduled Flows are caused by the transition to more and more renewable energy sources and the rising complexity of the European transnational energy market with insufficient price signals. To identify different flow types, the Full Line Decomposition (FLD) method can be used. The trend of grid extension goes more towards flexible AC transmission systems (FACTS) which have to be considered in a special way, since the actively changed power flow cannot be identified by FLD. New methods have to be developed. This publication presents a way to calculate and to classify partial power flows caused by FACTS, especially by high voltage DC (HVDC) transmission systems using the proportional sharing principle.