Analysis of the equivalent fault characteristics of DC system and its impact on distance protection based on power-frequency variation

• Main Authors: Dongxiao Cai, Haifeng Li, Xinchi Zhu
• Format: Article
• Language: English
• Published: Wiley 2019-04-01
• Series: The Journal of Engineering
• Subjects: HVDC power transmission; power transmission protection; power transmission faults; HVDC power convertors; power system stability; equivalent fault characteristics; distance protection; response characteristics; high-voltage DC control system; sending-end AC system; fault super-imposed network; equivalent power-frequency variation impedance; HVDC control system; fault conditions; mathematical derivation; PSCAD; EMTDC
• Online Access: https://digital-library.theiet.org/content/journals/10.1049/joe.2018.8872

Here, the response characteristics of high-voltage DC (HVDC) control system are studied in the case that fault occurs in the sending-end AC system. Then the characteristics of DC system which is equivalent to power-frequency variation impedance in the fault super-imposed network are analysed by mathematical derivation and verified by simulations on PSCAD/EMTDC. The result shows that the equivalent power-frequency variation impedance of HVDC system is affected by the rated capacity and the parameters of HVDC control system. The power-frequency variation impedance becomes capacitive under certain fault conditions, which reduces the zone of distance protection based on power-frequency variation and even leads to the operation failure.