Aiming at the issues of existing traveling wave location methods

such as high sensitivity to wave velocity

poor resistance to synchronization errors

difficulty in calibrating the wave head of reflected waves

and poor adaptability in multi-terminal HVDC systems

a fault location method for hybrid multi-terminal HVDC lines based on the wave velocity scale factor is proposed. First

the variation characteristics of wave velocity along the line are analyzed. By leveraging the fact that the wave velocities of different modulus at the same measuring point exhibit the same trend but different rates of wave velocity variation

a wave velocity scale factor which can indirectly reflect the fault distance is defined. Second

the fitting curve and calculation curve between the scale factor and the fault distance are solved by interpolation fitting and quantitative derivation

respectively. Based on the monotone difference of the above curves

a fault location scheme is proposed to solve the fault distance with parallel curves. To accurately identify the fault traveling wave head

a wave head calibration method combining robust local mean decomposition and multi-resolution singular value decomposition is proposed. Based on the calibration results

a time-delay-based criterion is designed for identifying the fault branch. Finally

simulation results show that the proposed location method has high accuracy

low computational complexity

immunity to synchronization error

strong resistance to transition resistance (500 Ω) and noise (20 dB)

and excellent adaptability across different transmission lines.