Single-ended active injection for fault location in hybrid MMC-HVDC systems

The traditional fault location methods on DC lines are facing many challenges such as low reliability and unsatisfied location accuracy. To ensure a more reliable fault recovery of DC line, a single-ended fault location method based on active detection is proposed for hybrid modular multilevel converter based high voltage DC transmission systems. The high controllability of hybrid MMC is utilized to activate the control strategy of injecting a sinusoidal signal. Furthermore, based on parameter identification and compensation methods for the distributed parameter model, the fault location equation with fault impedance parameters is formulated. Finally, the fault location can be identified under different fault scenarios. Simulation results verify the effectiveness and accuracy of the proposed active detection method. The proposed method can pinpoint the fault location with a lower sampling rate, its accuracy is not influenced by increasing of the line length and variation of the fault impedance.