Implementation of a novel unified power flow controller into Newton-Raphson load flow

This paper presents a novel structure of the unified power flow controller (UPFC) and proposes a load flow method for power systems with this kind of UPFCs. The novel UPFC structure has been applied in the Nanjing UPFC project, where the shunt converter is connected to a 35 kV bus, while two series converters are installed on two 220 kV lines. In this paper, the equivalent model of the novel UPFC is analyzed. Then a load flow method is proposed based on the power injection model and Newton-Raphson algorithm. The method can deal with the UPFC of both the novel structure and the conventional structure. The feasibility of the method is validated by test cases of the modified 39-bus New England system. The results show that the iteration number is acceptable under various operation conditions.