School of Electrical Engineering, Shandong University, Jinan250061, China

The accurate and reliable detection of high-impedance grounding fault (HIGF) is challenging in the fault handling of distribution networks, and the normal capacitor switching operations can cause interference. Addressing this problem, a disturbance-resistant detection method for HIGFs based on zero-sequence Lissajous curve analysis is proposed in this paper. First, the zero-sequence electrical quantities of HIGFs and capacitor switching disturbances are theoretically derived. There is no regular difference from the perspective of traditional time-frequency domain features between the two, thereby clarifying the cause of the interference. Further, the zero-sequence current and voltage waveforms are reconstructed into zero-sequence Lissajous curves. A quantitative index for the distortion complexity of the Lissajous curve trajectory shape based on the mathematical morphology theory is proposed, and an adaptive starting criterion is designed in combination with the probability distribution law of the zero-sequence Lissajous curve area. A disturbance-resistant detection method for HIGFs in the noise scenario is presented. Finally, the effectiveness and reliability of the proposed method are verified through electromagnetic transient simulation cases and real fault tests in the distribution network.

This work is supported by National Natural Science Foundation of China (No. 52107109) and Shandong Provincial Natural Science Foundation of China (No. ZR2021QE145).