<p>Commutation failure in high voltage direct current (HVDC) transmission is commonly attributed to disturbances in the inverter-side AC system or to converter-valve malfunctions. However, engineering practices show that faults in the sending-end AC network may likewise trigger commutation failure at the inverter. To address this issue, a fault location scheme of HVDC rectifier station based on the temporal feature of AC current state integral is proposed. Firstly, the fault characteristics of internal and external faults are analyzed, and it is found that when the fault occurs within the rectifier station, it leads to a significant reduction in the state temporal feature of the commutation valve group compared to the normal temporal feature, while the fault occurs outside of the rectifier station, the change in the state temporal feature of the commutation valve group remains within a small threshold compared to the normal temporal feature. Secondly, exploiting the differences in temporal feature of AC current state integral between internal and external faults, both types of faults can be accurately identified. Finally, the simulation results confirm that the proposed fault location scheme effectively differentiates between internal and external faults. It achieves an identification accuracy of over 97% and is less affected by noise interference.</p>