Single‐end protection algorithm for HVDC transmission lines based on the current difference

Abstract

This study presents a single-end protection algorithm for current source converter (CSC) high-voltage direct current (HVDC) transmission lines to solve shortcomings such as inadequate sensitivity, low speed and the need for communication link of conventional protection schemes. The proposed algorithm uses the average of DC line current at the rectifier terminal, sampled at 4 kHz within a 5 ms window, for simultaneous fault detection and faulted pole selection. For fault discrimination, the algorithm uses the average of second-order difference of the sampled current data. The algorithm is verified by extensive simulation studies using a CSC-HVDC test system modelled in PSCAD, as well as field data. The simulation results show fast and reliable protection of CSC-HVDC lines under different fault conditions including high-fault resistances. Moreover, the novel protection algorithm is stable against resistive–inductive faults, power flow changes, change of data window length, lightning interference and size of smoothing reactor. The algorithm does not require a communication link as used by numerous previous methods. It has a low computational burden, low sampling frequency and can be easily implemented in practical CSC-HVDC systems without extra arrangements as the required signals are readily available in the existing measuring hardware platforms.