DC fault arc detection method

An arc detection and DC fault technology, applied in power testing, measuring electricity, photovoltaic power generation, etc., can solve problems such as unusability, frequent false alarms, noise interference, etc.

Inactive Publication Date: 2015-11-25
SHANGHAI CHINT POWER SYST
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  • Abstract
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  • Claims
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Problems solved by technology

But the disadvantage is that it is also subject to the noise interference caused by the power electronic circuit itself and the surrounding equipment. When the noise signal in the DC current of the equipment itself is large, this solution cannot be used or frequently false alarms

Method used

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Experimental program
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Embodiment approach

[0045] 1) DC current is sampled by pulse transformer, band-pass filter, AD converter and MCU processor to obtain current data, such as Figure 5 .

[0046] 2) In the processing part of the MCU, the sampled data is passed through the Hanlin window and then FFT is performed to convert the time domain to the frequency domain, and the data logic processing is performed after calculating the amplitude of the high-frequency signal, such as Image 6 .

[0047] 3) The data logic processing part mainly uses the noise signal generated by the machine's own characteristics. The noise signal of the machine is mainly at the multiplier of the machine switching frequency. Figure 4 is the frequency spectrum of an arc fault, image 3 is the spectrum without arc fault.

[0048] The switching frequency of the example machine in the figure is 16k, as shown in the frequency spectrum, no matter whether an arc fault occurs or not, the machine has obvious noise signals around 16k, 32k, and 48k.

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Abstract

The invention relates to a DC fault arc detection method. The method is characterized by comprising the following steps of 1, sampling, filtering and conducting the fast Fourier transformation on an input current of a high-frequency power electronic converter to obtain an amplitude-versus-frequency curve for the high-frequency components of the current; 2, selecting at least one frequency band containing a switching frequency or a multiple frequency from the amplitude-versus-frequency curve, and calculating the peak value D1 of the magnitude of the curve and the mean value D2 of the magnitude of the curve within the selected frequency band. Based on the change of the distance between the peak value D1 and the mean value D2, whether an arc is generated or not can be judged. If the mean value D2 gets closer to the peak value D1, the arc is judged to be generated. Otherwise, no arc is generated. According to the novel DC fault arc detection method, based on the own characteristics of the converter, noise signals are generated by the high-frequency components of the direct current at the frequency multiplication points of the switching frequency of the converter. By utilizing the noise signals, the arc spectrum of an arc fault can be analyzed and calculated. In this way, whether the arc fault occurs or not can be detected.

Description

technical field [0001] The invention proposes a new method for DC fault arc detection, which can effectively distinguish whether or not a fault arc occurs, and report an error in time after detecting a fault arc, thereby improving system security. The invention can be applied in the field of DC power converters, such as UPS battery systems , Photovoltaic power generation system, etc. Background technique [0002] In recent years, with the rapid development of clean energy and energy storage systems, DC power conversion systems have been greatly developed. Due to the large current and high voltage of these systems, arc faults are more likely to occur. [0003] Arc refers to the discharge phenomenon caused by poor contact caused by unreliable connection of joints or insulation degradation of joints and wires, and unreliable connection between contacts or between contacts and other conductors. Arc is the main cause of fire in the DC system, timely and accurate detection of the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/12H02S50/00
CPCG01R31/129G01R31/40H02S50/10Y02E10/50G01R31/12G01R31/1272
Inventor 张玉林刘蓉张俊
Owner SHANGHAI CHINT POWER SYST
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