Novel small-current grounding system transient line selection method

A technology of small current grounding and line selection method, which is applied in the direction of measuring electricity, measuring electrical variables, measuring devices, etc., can solve the problem of low accuracy, and achieve the effects of improving accuracy, suppressing white noise, and strong anti-noise ability.

Inactive Publication Date: 2016-10-12
CHENGDU UNIVERSITY OF TECHNOLOGY
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Problems solved by technology

[0004] The technical problem to be solved by the present invention is that the first half-wave method, wavelet method and energy method based on transie...

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  • Novel small-current grounding system transient line selection method
  • Novel small-current grounding system transient line selection method
  • Novel small-current grounding system transient line selection method

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Embodiment Construction

[0021] Below in conjunction with accompanying drawing and example the invention is further described, and the present invention comprises specific following steps:

[0022] Step 1. Fault line selection logic start: When the system is running normally, the zero-sequence voltage of the small current grounding system is zero, and the three-phase phase voltage is balanced. When a single-phase grounding fault occurs, its zero-sequence voltage is greater than zero, and the fault phase voltage decreases , the non-fault phase voltage rises, therefore, it can be judged by the instantaneous value of the bus zero-sequence voltage being greater than the zero-sequence voltage set value and the rise of the non-fault phase voltage exceeding the set value. When the conditions are met, the fault line selection device Start; the zero-sequence voltage setting value is 0.15 times the bus phase voltage, and the non-fault phase voltage setting value is 1.1 times the bus phase voltage.

[0023] Step...

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Abstract

The invention discloses a novel mall-current grounding system transient line selection method, and the method comprises the following steps: starting a fault line selection logic; collecting the fault transient current data of all branch circuits on a bus; calculating zero sequence fault transient currents of the circuits and bus; calculating the spectral kurtosis of the circuits and bus; and carrying out line selection according to the spectral kurtosis of the circuits and bus. The method is very strong in anti-noise capability, and can completely inhibit white noise theoretically. When a fault angle is smaller or a grounding resistance is big, a fault transient current is smaller, thereby causing line selection through a first half wave method, an energy method, a wavelet method and other methods based on a transient component to be difficult. The method provided by the invention takes the non-stationarity and nongaussianity of signals as characteristic values for judgment, avoids the above impact, achieves the correct line selection, and improves the accuracy of line selection.

Description

technical field [0001] The invention relates to a line selection method for a single-phase ground fault in a small-current grounding system, in particular to a method for selecting a line by using a transient signal when a single-phase ground fault occurs in a small-current grounding system. Background technique [0002] The low-current grounding method is widely used in my country's distribution network. This grounding method does not form a low-impedance short-circuit circuit when a single-phase ground fault occurs, and the grounding current is very small, so it can run for 1 to 2 hours with a fault, but it can be used for a long time. Phase-to-ground operation may cause two-phase to ground short-circuit, especially when intermittent arc-to-ground occurs, it can cause arc overvoltage and threaten the system insulation. Therefore, the faulty line should be found and cut off as soon as possible. [0003] Edited by Pang Qingle, the monograph "Small Current Grounding Fault Line...

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Application Information

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IPC IPC(8): G01R31/02
CPCG01R31/50
Inventor 顾民葛良全蒋开明李琳琳胡传皓杨小峰
Owner CHENGDU UNIVERSITY OF TECHNOLOGY
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