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Single-phase earth fault line selection method based on multiple frequency zero sequence electric signals

A technology of single-phase ground fault and line selection method, which is applied in the directions of fault location, measuring electricity, spectrum analysis, etc., can solve problems such as difficult and incomprehensible analysis of line selection, and achieve high precision and reliability, good social and economic benefits , to avoid the effect of misjudgment

Inactive Publication Date: 2018-01-19
HANGZHOU LINGER ELECTRIC POWER TECH CO LTD
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Problems solved by technology

After a single-phase ground fault occurs in a low-voltage distribution network with different grounding methods, the methods for distinguishing the faulty

Method used

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  • Single-phase earth fault line selection method based on multiple frequency zero sequence electric signals

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Embodiment

[0029] Example: such as figure 1 As shown, a single-phase ground fault line selection method for low-voltage distribution network system of power system. FTU monitors the operating status of the line and section switch and controls the section switch. When a short-circuit fault occurs on the line, the FTU detects the overcurrent phenomenon, and accurately captures the zero-sequence current and voltage signals of 4 cycles after the fault through the terminals installed at different positions on the line. Then the FFT algorithm is used to analyze the harmonics of the zero-sequence electrical signals of the four cycles of the line.

[0030] The circuit structure of the method includes an input terminal with a three-phase current I A , I B , I C Connected zero-sequence filter, the other input terminal is connected to the three-phase voltage U A ,U B ,U C Connected zero-sequence filter; the output terminals of the zero-sequence filter are respectively connected with the FFT an...

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Abstract

The invention relates to a single-phase earth fault line selection method based on multiple frequency zero sequence electric signals. The method comprises the following steps: capturing zero sequencecurrent and voltage signals in multiple periods after a fault occurs through a terminal arranged on a line; adopting an FFT algorithm or a harmonic wave wavelet algorithm to carry out harmonic wave analysis on the zero frequency electric signals in the multiple periods; obtaining amplitudes and phases of zero sequence currents at multiple frequencies and also phases of zero sequence voltages at three frequencies; calculating corresponding zero sequence current change rates g1, g2 and g3, and calculating phase ratios [alpha]1, [alpha]2 and [alpha]3 between the zero frequency voltages and the zero frequency currents; and judging whether an earth fault of the line occurs through multiple criteria. The beneficial effects of the method are as follows: judgment is realized through multiple frequency electric signals, the characteristic of a system that different frequencies correspond to different grounding ways helps to avoid misjudgement if only one frequency exists, and the purpose of accurate judgment of a single-phase earth fault outgoing line is achieved.

Description

technical field [0001] The invention relates to the field of distribution of electric power systems, in particular to a method for line selection of single-phase grounding faults in a low-voltage distribution network. Background technique [0002] At present, most of my country's distribution network adopts the non-effective neutral point grounding system, and the single-phase grounding fault accounts for more than 80% of the total faults. With the increase of feeders, the capacitive current increases, and long-term operation is prone to single-phase ground faults becoming multi-point ground short-circuit faults. Arc grounding will also cause system overvoltage, damage equipment, and other problems, thereby destroying the safe operation of the system. Therefore, it is very important to find the fault line and fault location in time. With the strengthening of the distribution network frame and the increase of branch lines, it is very difficult to find out the specific fault ...

Claims

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Application Information

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IPC IPC(8): G01R31/02G01R31/08G01R23/165
Inventor 陈剑萍
Owner HANGZHOU LINGER ELECTRIC POWER TECH CO LTD
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