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Line selection method for small current single-phase ground fault based on fast s-transformation

A technology of single-phase ground fault and line selection method, applied in the direction of fault location, etc., can solve the problem of low accuracy, achieve good adaptability, and improve the effect of line selection accuracy

Active Publication Date: 2019-09-27
XIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to provide a small current single-phase ground fault line selection method based on fast S transformation, which solves the problem of low accuracy of the existing line selection method, thereby improving the accuracy of line selection and the reliability of the power supply system

Method used

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  • Line selection method for small current single-phase ground fault based on fast s-transformation
  • Line selection method for small current single-phase ground fault based on fast s-transformation
  • Line selection method for small current single-phase ground fault based on fast s-transformation

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Embodiment

[0062] In order to verify the effectiveness of the method of the present invention, according to the State Grid Corporation "Technical Specifications for Line Selection Devices for Single-phase Grounding Faults in Small Current Grounding Systems", the principle of the functional test circuit for simulating single-phase grounding faults in small current grounding systems is as follows image 3 shown.

[0063] image 3 Among them, the switch K1 and K2 are opened for the neutral point ungrounded system; the switch K2 is opened and K1 is closed for the neutral point grounded system through resistance; the switch K1 is opened and K2 is closed for the neutral point grounded system through the arc suppression coil. I 1 * and I 1 It is the zero-sequence current terminal of the first feeder (analog distribution network feeder 1), which is connected to the input terminal of the current transformer of the line selection device, I 1 * is the polarity terminal, I 1 It is the non-polar ...

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Abstract

The invention discloses a small-current single-phase grounding fault line selection method based on fast S transform. The small-current single-phase grounding fault line selection method comprises the steps of carrying out time-frequency analysis on transient zero-sequence currents of a faulty line and non-fault lines by utilizing fast S transform, calculating to obtain a one-dimensional mode coefficient and a one-dimensional phase angle value of each line after FST, calculating an energy value of each line, regarding the line with the maximum energy value as an alternative faulty line, regarding a non-alternative line as a phase angle reference comparison line, and taking whether an absolute value of a phase angle difference at a main frequency point in a transient feature frequency band after FST of the alternative faulty line and the phase angle reference comparison line is greater than a set threshold value as a line selection criterion. The small-current single-phase grounding fault line selection method avoids the influence of grid interference and accidental factors, makes full use of the transient signal time, amplitude, frequency and phase angle information, can select the faulty line quickly and accurately, is not affected by the neutral point grounding method, and has good adaptability.

Description

technical field [0001] The invention belongs to the technical field of intelligent state detection of power systems, and in particular relates to a small current single-phase ground fault line selection method based on fast S transformation. Background technique [0002] The reliability of power system power supply is closely related to industrial and agricultural production. The distribution network below 66kV in China widely adopts the small current grounding method, also known as the neutral point non-direct grounding system. The neutral point is grounded through a high-value resistance system. When a ground fault occurs in these three distribution network grounding systems, the current flowing through the grounding point is small, so it is called a small current grounding system. [0003] According to statistics, more than 80% of the faults in the small current grounding system are single-phase grounding faults. When a single-phase ground fault occurs in a small curre...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/08
Inventor 焦尚彬师延金张青
Owner XIAN UNIV OF TECH
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