Detection and Classification of Faults in VSC-HVDC System Based on Single End Ground and Pole Differential Current Components

The simple and reliable protection of VSC-HVDC system guaranties the uninterrupted and economical supply of distributed generation integrated with AC grid. A verity of protection schemes available for HVDC system has some merits and demerits. However, the choice of protection schemes selected should also be based on its simplicity, reliability, and speed of operation. This paper presents a simplified protection schemes based on single end measurement with least requirement of communication channels. The scheme is based on difference in pole current and moving average of ground mode current measured at any one of the terminals of a bipolar VSC-HVDC system. The differential pole current detects the presence of any internal fault and an additional estimation of moving average of ground mode current classifies the nature of internal faults. The scheme is unaffected from the magnitude of distributed overhead line or cable capacitance unlike in conventional differential protection schemes. To implement the proposed protection scheme a VSC-HVDC system of ±100 kV, 200 MVA is used in MATLAB/Simulink software. The length of transmission system is 150 km which is used to integrate the renewable generation from the conventional AC grids.