Clustering-based positioning method for single-phase grounding fault section of distribution network

Abstract

The invention relates to a clustering-based positioning method for a single-phase grounding fault section of a distribution network. The method comprises the following steps of: performing the determination of a fault time and the self-synchronization of the positioning signals of each measuring point of a fault line by time-frequency atomic decomposition; extracting each frequency component and the corresponding energy of fault components of an alpha mode component of a transient phase current after the fault by using the frequency dividing capability of the time-frequency atomic decomposition, constructing a normalized characteristic quantity of the energy and the frequency; and classifying the normalized characteristic quantity of the frequency and the energy by using a K-means clustering method, and selecting the fault line and the fault section. The method provided by the invention can accurately perform line selection and positioning on five kinds of typical grounding faults suchas the small resistance grounding of a phase voltage over peak, the small resistance grounding of a phase voltage zero crossing, the high resistance grounding of the phase voltage over peak, the highresistance grounding of the phase voltage zero crossing, and a bus fault. The method has strong adaptability. The results are still accurate and reliable under the influence of electromagnetic noise,arc fault, arc suppression coil compensation, and other factors.

Description

technical field [0001] The invention relates to a method for locating a single-phase ground fault section of a distribution network based on clustering. Background technique [0002] The probability of single-phase ground faults in my country's distribution network is the highest, accounting for more than 80% of the total faults. The resonant grounding system is widely used in the medium-voltage distribution network because it can still ensure the symmetry of the line voltage after a single-phase ground fault occurs, and the fault current is small, and the regulations stipulate that it can continue to run for 1 to 2 hours. At this time, if the fault can be found and removed as soon as possible, the operation reliability of the distribution network will be greatly increased. Otherwise, long-term fault operation will easily lead to the expansion of the fault range and endanger the safety of the system. However, due to the overcompensation of the arc-suppression coil, the stea...

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Problems solved by technology

At this time, if the fault can be found and removed as soon as possible, the operation reliability of the distribution network will be greatly increased. Otherwise, long-term fault operation will easily lead to the expansion of the fault range and endanger the safety of the system.

However, due to the overcompensation of the arc suppression coil destroying the steady-state characteristics of the fault current, coupled with the influence of factors such as small fault current, unstable arc, difficult to accurately synchronize signals for positioning, and limited acquisition of voltage and current signals at outdoor measurement points, Line selection and positioning are still difficult problems in distribution network protection

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