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

Abstract

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.

Keywords

• 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