A series arc detection method for low-voltage distribution network

Abstract

The invention relates to a series arc detection method for a low-voltage distribution network, which belongs to the field of electrical engineering measurement. It is characterized in that it includes the following steps: step a, setting a monitoring node in the line to be tested; step b, synchronously looking at the line to be tested and collecting the voltage at both ends; step c, performing filtering processing on Uo; step d, obtaining Us- The waveform of Uo; step e, if a series arc fault occurs, go to the next step, if no series arc fault occurs, return to step b; step f, count the number of faults; if it exceeds the preset threshold, cut off the line or send an alarm signal. If the preset threshold value is not exceeded, return to step f; in the series arc detection method for low-voltage distribution network, the detection of series fault arc is realized by measuring the voltage difference between the head end and the end of the line, and the voltage information is used to judge the series fault The existence of arc has the advantage of being less affected by load type and load power, and its fault characteristics are more obvious, so its judgment accuracy is higher.

Description

technical field [0001] The invention relates to a series arc detection method for a low-voltage distribution network, which belongs to the field of electrical engineering measurement. Background technique [0002] Series arc fault is a series discharge phenomenon caused by damaged conductors, poor contact, loose terminals or poor contact. The series fault arc point and the load are in series relationship in the line, and it has the characteristics of continuous occurrence. When the series arc continues to occur for a period of time, it may cause a fire. When the series arc occurs, the current waveform generally appears: the current waveform has zero rest area, the current rise rate becomes higher, the current harmonic content increases, the current effective value becomes smaller, the positive and negative half cycles are no longer symmetrical, and the load is different. , The load power is different, the performance of these fault characteristics will be different. Existi...

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Problems solved by technology

[0003] The difficulties in series fault arc detection include: (1) The series fault arc is connected in series with the end load, and its fault current is equal to the load current, so it cannot be protected by the current threshold; (2) There are various loads in low-voltage distribution lines, The load current in normal operation of this type of equipment has the same or similar current waveform characteristics as that of linear loads when a series fault arc occurs, so it is difficult to find a fault characteristic detection standard suitable for various loads, resulting in the success of the current series fault arc detection low rate

(3) When a series fault arc occurs, its current fault characteristics will be affected by the load power

(4) Partial loads also have the current characteristics of series fault arcs when starting, so it is easy to cause misjudgment

(5) Partial loads such as arc welders, arcs generated when brushed motors are working, and arcs generated when plugging and unplugging sockets have fault characteristics similar to series fault arcs, which increases the difficulty of detecting series fault arcs

(6) For weak series arc faults with very short arc time or very small arc current, the fault characteristic quantity in the current waveform is often not obvious, which makes it difficult to detect weak series fault arcs, and lays hidden dangers for arc-induced fires

[0012] This method considers that when there is an arc, the difference between the voltage waveforms of the load terminals in two adjacent cycles is relatively large, so the average value of the voltage difference waveforms of adjacent cycles is larger than that of the adjacent cycles when there is no arc, because when the arc occurs The characteristic is random, so this method is prone to misjudgment, and this method is also prone to misjudgment when the load terminal voltage changes caused by the load type and load power change when the line is normal

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