1.College of Energy and Electrical Engineering, Hohai University, Nanjing 211100, China;2.Hunan Key Laboratory of Smart Grid Operation and Control (Changsha University of Science and Technology), Changsha 410114, China

In order to improve the sensitivity of high-resistance grounding fault detection in distribution networks, a single-phase grounding fault detection method for tracking and monitoring parameter asymmetry of distribution lines is proposed. Aiming at the random difference characteristics of distribution parameters of lines in the distribution network, the parameters characterizing the parameter asymmetry of lines are defined, the critical conditions and flow path of generating zero-sequence current of distribution lines are demonstrated, the equivalent operation model of the zero-sequence network for the distribution network considering the asymmetric random difference of line parameters is established, and the measurement methods of parameters such as distribution line impedance to ground and asymmetry are proposed to realize single-phase grounding fault line selection, phase selection and transition resistance measurement. The fault detection scheme is optimized according to the fault types. In the case of high-resistance grounding, the zero-sequence voltage is artificially adjusted to improve the sensitivity of fault detection. In the case of a low-resistance fault, the fault is quickly detected only relying on the change of zero-sequence electrical information. Simulation experiment results verify the effectiveness of the proposed detection method.

This work is supported by National Natural Science Foundation of China (No. 51737002), Youth Fund of Jiangsu Province Natural Science Foundation of China (No. BK20190490) and Post-doctoral Science Foundation of China (No. 2020M671318).