Research On Single-phase Grounding Fault Detection Based On HHT

The small current single-phase grounding fault is one of the most commonfaults in the distribution network, as well as a hot research topic in the field ofpower system automation. Due to the impact of the grid structure, line type, faultconditions and other factors, the current line selection method still haveshortages, so it is important to find a strong adaptability detection method.In this paper, introduce a method for non-stationary, non-linear signalanalysis method–Hilbert Huang Transform (HHT) to small current groundingsystem for the analysis and line selection in single-phase grounding fault, theHHT can extract the rich transient time-frequency information fromnon-stationary, nonlinear fault current signal and combine with informationentropy to propose a classification line selection method based on the systemHilbert marginal spectrum entropy measure (HMSEM). Firstly, introduce theHHT method and a number of improvements in detail, and apply it to signalmutation detection and frequency analysis. Secondly, analyse the steady-statecharacteristics and transient characteristics of the small current single-phasegrounding fault under the different grid structures, and feeder current travelingwave zero-mode component characteristics of the post-fault system whichprovides theoretical guidance for fault detection. Make use of EMTP-ATPsimulation resonant grounding system single-phase grounding fault and analysethe variety of factors which affect the feeder zero sequence current signal,conclude that fault phase and grounding resistance have a greater impact on thecharacteristics of the signal. Research the influence of fault phase and groundingresistance frequency characteristics to signal transient component by selectingthe appropriate time window to get the signal transient component, also use theHHT to analysis frequency. The ensemble empirical mode decomposition (EEMD)is introduced to the signal mutation detection in order to determine the fault time.By the introduction of Hilbert marginal spectrum entropy concept, and combinedwith previously the fault phase as well as the grounding resistance influence,conclude that the Hilbert marginal spectrum entropy will increase with theincrease of the fault phase as well as decrease with the increase of the groundingresistance, and grounding resistance plays a dominant role. Finally, put forwardthe line selection method based on the system Hilbert marginal spectrum entropy measure, the simulation effectiveness of this line selection also prove the strongadaptability to fault conditions.