Fault arc protection method for low-voltage direct-current power distribution and utilization system

Abstract

The invention discloses a fault arc protection method for a low-voltage direct-current power distribution and utilization system. For a collected system current signal containing the direct current component, the Rbio3.1 is used for extracting the amplitude increase of the frequency information in the 60kHz range triggered by the fault arc, and for the collected system current signal without the direct current component, the Rbio3.1 is used for extracting the amplitude increase of the frequency information in the 150kHz range triggered by the fault arc; according to the increase trend of the amplitude of the direct current component or the distribution of the frequency spectrum amplitude of the frequency domain characteristic quantity in a smaller amplitude range, the arc-like phenomena such as starting or power adjustment and increase of the system are identified, and according to the amplitude decrease trend of the frequency domain characteristic quantity or the distribution of the frequency domain characteristic quantity in the smaller amplitude range, the arc-like phenomena such as power adjustment and decrease or shutdown of the system are identified. The fault arc protection method is provided for different current signals, fault arc and arc-like working conditions with various coupling characteristic changes in the system can be accurately distinguished, and a guarantee is provided for safe operation of a power system with new energy as a main body.

Description

technical field [0001] The invention belongs to the technical field of DC electrical fault detection, and specifically relates to the use of time-domain feature quantities and frequency-domain feature quantities, and through the application of feature quantity change trends and non-supervised machine learning models to analyze the distribution range of feature amplitudes, to perform low-voltage direct current distribution and consumption systems. Arc fault detection. Background technique [0002] "Carbon peaking" and "carbon neutrality" are the sustainable development direction of society. With the high proportion of distributed energy and power electronic equipment connected, when the source and load are both in the form of DC, the low-voltage DC power distribution system can give full play to the characteristics of convenient access to renewable energy and efficient power utilization. It provides green, efficient, and safe DC power support for the implementation of new di...

AI Technical Summary

Problems solved by technology

At each voltage level, the nonlinear, random, and strong coupling interference generated by source loads and power electronic equipment is different from the interference of photovoltaic modules on arc fault characteristics, so in these extended DC terminal scenarios will form The new DC fault arc characteristics, in some DC scenarios that have a shielding effect on the fault arc characteristics, the existing photovoltaic fault arc characteristics may not be able to present different fault arc states and fail

At the same time, unlike the relatively simple source-load composition and branch structure of the DC side of the photovoltaic system, the low-voltage DC power distribution system is complex due to factors such as multiple voltage levels, multiple source loads, and multiple types of power electronic devices. Open grid structure will bring new arc fault protection problems

Although the current AC fault arc detection method has been extended to the power distribution side according to UL and IEC standards, the time-frequency domain characteristics of the zero-crossing point used by the AC fault arc cannot directly meet the arc protection requirements of the DC power distribution system.

[0004] Although the Chinese patent CN111999753A mentions the application of wavelet packet decomposition method to detect ground faults, it does not clearly specify the type of wavelet base used and the specific frequency band parameters, and cannot be directly applied to fault arc protection of low-voltage DC power distribution systems

When only the wavelet packet decomposition method is applied to arc fault protection, there are mainly the following two types of problems that are difficult to solve: 1) The characteristic amplitude of some arc faults does not increase, which is difficult to identify; 2) In the AC power supply system The applied ground fault detection method based on multi-feature weighting is not suitable for effective identification of various arc situations

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