Series arcing fault identifying method for low-voltage system

Abstract

The invention provides a series arcing fault identifying method for a low-voltage system and relates to the technical field of the protection of power supplies. The method comprises the following steps of: firstly acquiring a current signal of a loop as a sample through a current detecting device; modeling the current signal and calculating a parameter vector AT and a reference vector AR by usinga 3-order auto-regression model; solving a characteristic value d2 of the current signal through squaring an euclidean distance; and judging whether series arcing fault occurs in the loop through comparing the characteristic value d2 with a preset threshold so as to realize the classified identification of current signals of an arcing fault loop and a normal loop. The method is suitable for identifying the series arcing fault in not only a linear load loop but also a nonlinear load loop, and the problem on identifying the current signals of the series arcing fault loop and the nonlinear load loop for the low-voltage system is effectively solved.

Description

technical field [0001] The invention relates to the technical field of power supply protection, in particular to a method for identifying a series arc fault. Background technique [0002] The existing data from the "2008 China Fire Statistical Yearbook" provided by the Fire Bureau of the Ministry of Public Security shows that 31% of fire accidents in the country are caused by electrical fires every year, and series arc faults are one of the main reasons for electrical fires. This is because the RMS value of the series arc fault loop current is in the same order of magnitude as the RMS value of the normal working loop current of the low-voltage power distribution system load. The common fault protection devices in the system, such as fuses, circuit breakers, and residual current protectors The series arc fault is insensitive and does not play a protective role, so the series arc fault is extremely difficult to be found, which constitutes a serious electrical fire hazard. [...

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Problems solved by technology

The detection of series arc faults in the low-voltage power distribution system faces the following difficulties: First, the low-voltage power distribution system has a variety of load combinations. During normal operation, the loop current waveform may mainly show linear characteristics (no harmonics), or may It mainly shows nonlinear characteristics (with harmonics or inter-harmonics). The load current waveform with nonlinear characteristics may be very similar to the current waveform when there is a series arc fault in the circuit, which will interfere with the arc fault detection; secondly, the influence of the arc There are many factors. The series fault arc has the characteristics of unstable arcing. For the fault arc generated by the same experimental equipment at different times, its time domain and frequency domain characteristics will be very different; therefore, using the traditional time domain, It is very difficult to identify series arc faults in low voltage distribution circuits by frequency domain analysis

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