Single-Pole Ground Fault Location Method for Multi-terminal Flexible DC Transmission Lines Based on LSSVM

In order to ensure the safe and stable operation of multi-terminal flexible DC system and improve the accuracy of single-pole grounding fault location of transmission lines. This paper proposes a single-pole grounding fault location method based on Least Squares Support Vector Machine (LSSVM). When the ground fault occurs, the line mode voltage of different sections in series is combined with the classification mechanism of least squares support vector machine to identify the fault section. Then, the frequency domain characteristics of the line mode voltage in this section are extracted by wavelet packet decomposition combined with Pearson correlation coefficient, and the LSSVM model is established based on the characteristic results to realize fault location. The sparrow search algorithm is used to optimize the parameters of LSSVM model. This paper established +/- 500kV four-terminal flexible DC simulation model for testing. The results show that the method has good anti-transition resistance ability, and the location error is within 0.37 km at the sampling frequency of 50 kHz.