A New Power Flow Controller Based on Dual-Excited Synchronous Machine

The dual-excited synchronous machine (DESM) with two field windings on the rotor can regulate the amplitude and phase angle of the stator voltage simultaneously, thus it can be instead of the converter and used in the power flow controller. This paper proposes a DESM-based power flow controller (DESM-based PFC), which has not only the function of the unified power flow controller (UPFC), but also the high reliability and overload capability. The topology structure and operating theory of the DESM-based PFC are presented. The mathematical model of the DESM-based PFC is established by coupling the connected coaxially traditional synchronous machine (TSM) and DESM, the parallel transformer and the series transformer. The control strategy is proposed according to the relationship between the line power flow and the d- and q-axis field currents of the DESM. A looped power grid is taken as example to study the independent and combined regulation of the line active and reactive by the DESM-based PFC, and further the power flow control characteristic of DESM-based PFC under different load variations is studied. The results show that the DESM-based PFC can regulate power flow and has better practicality and robustness. The study can provide a new solution for the flexible regulation of the power flow in the power grid.