A fault location method for double-circuit HVDC transmission lines on the same tower based on mixed modulus

Double-circuit HVDC transmission lines on the same tower have becoming an inexorable trend for they can not only increase unit corridor area transmission ability but also reduce construction costs. After thoroughly study the phase-mode transformation method for double-circuit HVDC lines and considering that in practice they are not transposed, a novel algorithm for locating faults using mixed modulus based on time-domain information is presented in this paper. This proposed algorithm basically uses the trait that the voltage distributions at both ends have minimum voltage-difference along a transmission line, which can be acquired by calculating the voltage and current measurements at two ends. A simulation of the Xiluodu-Guangdong ±500kV double-circuit HVDC transmission lines on the same tower is established to verify the proposed algorithm in PSCAD/EMTDC.