Fast single-end line protection method for the meshed multi-terminal HVDC grid

Abstract

In view of the short-circuit fault characteristics, the protection technique of the dc lines limits the development of the modular multi-level converter (MMC)-based HVDC grid in a large extent. This study derives the calculation formulas of the transient voltages of internal and external faults and proposes a single-end protection scheme based on the transition period (TP) from the abrupt changing point to the first extreme point of the fault voltage. Due to the current-limiting reactors, the TP of the internal fault is much shorter than that of the external fault, which is used to discriminate internal fault from external fault. A four-terminal symmetrical bipolar HVDC grid based on MMC is modelled using PSCAD/EMTDC, and simulation results demonstrate the validity of the new proposed dc transmission line protection method.

Keywords

• HVDC power transmission
• power transmission lines
• HVDC power convertors
• power grids
• power transmission protection
• fault diagnosis
• power transmission faults
• current limiting reactors
• short-circuit fault characteristics
• protection technique
• multilevel converter-based HVDC grid
• MMC
• transient voltages
• internal faults
• external faults
• single-end protection scheme
• transition period
• TP
• abrupt changing point
• fault voltage
• four-terminal symmetrical bipolar HVDC grid
• dc transmission line protection method
• fast single-end line protection method
• meshed multiterminal HVDC grid
• current-limiting reactors
• PSCAD
• EMTDC