One quick-action protection scheme for VSC-HVDC transmission lines with considering the frequency-dependent characteristics of cables

摘要

The protection strategy for VSC-HVDC transmission has a poor performance in practice, and it is necessary to explore new protection schemes. Most transmission lines of VSC-HVDC use the cables which have obvious frequency-dependent characteristics, and large capacitors are installed at both ends of transmission lines, making it possible to construct the new single-end protections. This paper analyzes the circuits' topology of VSC-HVDC transmission line under internal and external faults, and then defines the transfer impedance of fault component circuits. With considering the frequency-dependent parameters of cables, it is found that the impedance of high frequency under external faults is quite larger than that under internal faults, which means that the high-frequency current can be used to distinguish internal and external faults. The simulation results prove the validity and good performance of the proposed protection scheme.