Novel protection method for VSC-HVDC transmission lines

Abstract

The large shunt capacitances on both sides of VSC-HVDC transmission line will block and reflect the travelling waves when a fault occurs on DC cable lines. When a forward fault occurs, the protection will detect the arrival of forward and backward travelling wave simultaneously. While for a backward fault, the arrival time difference of the forward and backward travelling wave head is obvious. According to this characteristic, this paper proposed a novel VSC-HVDC directional pilot protection based on the propagation time difference of directional travelling wave and the stationary wavelet transform (SWT) is used to identify the initial travelling wave head. A two-terminal VSC-HVDC system is modelled in PSCAD/EMTDC, and various faults scenarios are simulated to verify the proposed method. The simulation results show that the proposed protection can identify internal faults from external faults quickly and reliably, and it is basically immune to fault resistance and fault distance, which has certain practical value.

Keywords

• power transmission protection
• power grids
• power transmission faults
• HVDC power transmission
• power transmission lines
• wavelet transforms
• fault diagnosis
• HVDC power convertors
• voltage-source convertors
• PSCAD/EMTDC
• VSC-HVDC directional pilot protection
• protection method
• fault resistance
• external faults
• internal faults
• faults scenarios
• two-terminal VSC-HVDC system
• initial travelling wave head
• directional travelling wave
• propagation time difference
• arrival time difference
• backward fault
• forward fault
• DC cable lines
• travelling waves