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Method for detecting high impedance grounding fault based on fault resistance nonlinear identification

A high-resistance ground fault and fault resistance technology, which is applied in the direction of measuring electricity, measuring devices, and measuring electrical variables, can solve the problems of low sensitivity of fault detection and ignoring the dynamic characteristics of fault current.

Active Publication Date: 2013-08-21
TSINGHUA UNIV
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Problems solved by technology

[0004] However, the above harmonic-based methods completely ignore the dynamic characteristics of the fault current, so the sensitivity of fault detection is not high

Method used

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  • Method for detecting high impedance grounding fault based on fault resistance nonlinear identification
  • Method for detecting high impedance grounding fault based on fault resistance nonlinear identification
  • Method for detecting high impedance grounding fault based on fault resistance nonlinear identification

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Embodiment Construction

[0023] The present invention will be described in detail below in conjunction with examples.

[0024] A high-resistance ground fault detection method based on nonlinear identification of fault resistance, including the following steps:

[0025] Step 1: Sampling the phase voltage and zero sequence current of the monitored feeder at a sampling frequency of 3kHz to obtain the power frequency cycle sampling value sequence u a (n), u b (n), u c (n), i 0 (n), n=1,2,……60, as follows;

[0026] u a (n)=[1074.0,590.9,107.4,-752.0,-1504.0,-2471.0,-3330.0,-3975.0,-4727.0,-5479.0,-6016.0,-6553.0,-6983.0,-7413.0,-7628.0,-7843.0, -7843.0, -7843.0, -7843.0, -7735.0, -7843.0, -7413.0, -7091.0, -6553.0, -5909.0, -5264.0, -4620.0, -3760.0, -2901.0, -1934.0, -966.9, -483.5, 0,859.5, 1719.0,2578.0,3330.0,4190.0,4835.0,5479.0,6124.0,6661.0,7091.0,7413.0,7628.0,7628.0,7682.0,7736.0,7735.0,7735.0,7628.0,7306.0,6876.0,6231.0,5694.0,4942.0,4297.0,3330.0,2578.0, 1612.0]

[0027] u b (n)=(6768.0,6983.0,7198.0,...

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Abstract

A method for detecting a high impedance grounding fault based on fault resistance nonlinear identification comprises the steps: collecting phase voltages of a detected feeder line and an instantaneous value of a zero sequence current, respectively calculating a correlation coefficient of each phase voltage and the zero sequence current, if the correlation coefficient of one phase voltage and the zero sequence current is larger than a threshold value R, fitting a current voltage characteristic curve composed of the phase voltage and the zero sequence current in a sectional and linear mode through a least square method, accordingly, calculating and obtaining a coefficient, namely, a fault resistance nonlinear coefficient which can effectively present characteristics of the high impedance grounding fault according to the slope of each fitting straight line, judging whether a suspected high impedance grounding fault exists by comparing the fault resistance nonlinear coefficient and the threshold value, continuously detecting the lasting time of the suspected high impedance grounding fault, and if the lasting time exceeds delayed time, finally judging that the high impedance grounding fault occurs. Compared with a detecting method based on a harmonic wave, the method achieves high sensitivity, and compared with a method simply based on the time domain amount, the method achieves a better noise resisting capacity.

Description

Technical field [0001] The invention belongs to the field of power system fault detection and protection, and in particular relates to a high-resistance grounding fault detection method based on nonlinear identification of fault resistance, which is used for detecting high-resistance grounding faults of distribution lines of a neutral point effective grounding system. technical background [0002] The rapid increase in the load rate of distribution lines and the wide application of cable lines have made the effective grounding of the neutral point of the distribution network more and more used. Neutral point effective grounding distribution lines are affected by power transmission corridors, natural environment and other factors, and are prone to single-phase high-resistance grounding faults through non-ideal conductors such as branches and sand. The fault current is limited by the impedance of the fault circuit, which is less than the zero-sequence overcurrent protection action ...

Claims

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Application Information

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IPC IPC(8): G01R31/02
Inventor 王宾耿建昭董新洲
Owner TSINGHUA UNIV
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