Research On Fault Feeder Selection For Single-Phase Grounding Fault In Distribution Grid Based On Transient Reactive Power

When single-phase grounding fault occurs in the distribution grid, it is allowed to continue running1to2hours. However, the non-faulty phase voltage rises to normal line voltage which puts a higher demand on the system’s insulation, this may enlarge the fault’s scope and harm degree. Therefore, how to detect the faulty line quickly and accurately is an important topic which is related to the reliability and security of the distribution grid’s operation.The faulty line selection methods based on steady-state information are easily affected by the arc、transition resistance、neutral point operation mode and so on, so it is increasingly difficult to meet the requirements and is gradually eliminated. Instead, the amount of transient information is very rich, and the transient signal amplitude is much larger than the steady-state signal’, this extremely benefits the line selection. So, this paper analyzes the distribution characteristics of the lines’zero-mode reactive power and proposes a new method to select line.The paper summarizes the distribution grid’s neutral point operation mode as well as the existing line selection methods at home and abroad. The steady-state and transient single-phase grounding fault feature are analyzed, in the process of transient analysis, electromagnetic coupling is eliminated and transient signal’s equivalent circuit and time-domain expressions are got with the use of phase-mode transformation theory. Then, the paper analyzes the phase-frequency characteristic of the transient-state signal and the distribution characteristic of transient-state zero-mode reactive power in feature band, meanwhile, the method of using Hilbert transformation to calculate the lines’zero-mode reactive power is put forward. Finally, by using PSCAD simulation software, a simulation model of distribution grid single-phase grounding fault is built, through the analysis of simulation results, the distribution characteristic of transient zero-mode reactive power and the effectiveness of faulty line selection based on transient zero-mode reactive power amplitude and direction are verified.. To some extent, the paper has reference value to those researches of faulty line selection based on transient-state information.