A novel whole-line quick-action protection principle for HVDC transmission lines using one-end currents

A novel quick-action high voltage direct current (HVDC) transmission line protection principle only using one-end current signals is proposed in order to solve the problems in traditional protection principles, such as poor reliability and insufficient sensitivity. By analyzing the impedance characteristic of the electric network, which is made of reactance and DC-filter of HVDC transmission systems, it is found that the difference of the impedance characteristic in some special frequency-bands is distinct when an internal or external fault of the DC line occurs. Furthermore it is obtained that the measured current is obviously different for some special frequency-band signals between internal or external faults. Compared with the traditional protection methods, the protection principle is simpler, the sample frequency could be lower, and it is easier to be implemented. It can be the primary protection of HVDC transmission lines instead of the current traveling wave protection. Simulation results show that the proposed protection principle can identify the fault pole and identify between the internal and external faults. It can rapidly operate with high sensitivity and selectivity in different fault conditions.