The influence of a VSC based HVDC link on distance protection relay assessed by CAPE software

The increasing rating and improved performance of self-commutated semiconductor devices have made possible Voltage-Sourced Converter based High Voltage DC transmission system. VSC-based HVDC power transmission is then becoming a more efficient solution for long distance power transmission, especially for off-shore wind plants. One of the advantages of VSC-based HVDC transmission system is its ability to independently control active and reactive power flow at the AC systems to which it is connected. Both in normal operation or under disturbances in the AC transmission system, the VSC-based HVDC can add additional controllability to the AC system; So that, VSC-based HVDC transmission system can enhance power system stability by modulating their active and reactive power. However, this flexibility is likely to affect the protective relay operation of transmission lines, particularly step distance protective relay. Thus, this paper presents the influence of the different control methods of a VSC-based HVDC transmission system on a distance protective relay.