Mahyar Abasi, Vahid Davatgaran, Morteza Azizi
With the increasing adoption of bipolar high-voltage direct-current (HVDC) transmission lines for wind farm integration, the development of fast, accurate, and communication-independent protection schemes has become a critical technical requirement. This paper proposes a comprehensive protection algorithm within an integrated single-ended framework that performs fault detection, fault classification, and fault location simultaneously using only local voltage and current measurements. In the detection stage, transient current signals are processed through common- and differential-mode decomposition to ensure fast and reliable fault inception identification. In the classification stage, the faulted pole and fault type are determined by exploiting the dynamic voltage patterns of the two poles. For fault location, an analytical model is developed based on the voltage-current relationships of the bipolar HVDC line, while explicitly accounting for self-resistance, mutual resistance, and inter-pole coupling effects. In addition, the protection thresholds are systematically defined using per-unit parameters and dimensionless indices, together with statistical criteria extracted from the system behavior under both normal and faulted conditions; this enhances their tunability, robustness, and applicability across different HVDC configurations. The proposed method is evaluated in the MATLAB/Simulink environment under varying operating conditions, fault resistance values, and line-parameter uncertainties. Simulation results show that the average and maximum fault detection delays are 3.32 ms and 4.96 ms, respectively. Moreover, the faulted pole is identified with complete accuracy, while the average and maximum fault-location errors are 0.69% and 0.98%, respectively, confirming the high speed, accuracy, and robustness of the proposed protection scheme.