Analysis and Control of Interline DC Power Flow Controller with Fault Current Limiting Function

In order to address the issue of insufficient power flow control capability and difficulty in limiting fault current in Multiterminal HVDC (MTDC) grids, this paper presents an interline DC power flow controller (IDCPFC) with fault current limiting function and its control method. The topology of IDCPFC is introduced, and the principles of power flow control and fault current limiting are analyzed by establishing equivalent circuit models. A time-sharing control method is proposed, which can realize the independent control of capacitor voltage and line current. The fault characteristics of IDCPFC are studied, and the control strategy under fault condition is proposed, which can realize the functions of limiting fault current and self-protection. The simulation model and down-scale experimental system of three-terminal DC system are built to verify the effectiveness of the IDCPDC under the conditions of power flow distribution and system fault.