Adaptive fault diagnosis method for microgrid inverter based on multi-band skew analysis

Abstract

The adaptive fault diagnosis method of microgrid inverter based on multi-band skewness analysis belongs to the field of microgrid fault diagnosis. This invention is based on the changes in signal characteristics in different frequency bands before and after the fault, extracts three-phase current decomposition coefficients in different frequency bands and multiple levels based on the discrete wavelet multi-resolution analysis method, and obtains the different frequency bands and multi-level decomposition of the fault detection signal through reconstruction. signal, and determine the optimal number of decomposition layers through energy analysis methods. Then, skewness analysis is performed on the multi-level decomposed signals in different frequency bands, and the skewness characteristic value of each decomposed signal is obtained to represent the degree of distortion of each decomposed signal due to faults. Finally, the distortion characteristic values ​​of each decomposed signal in different frequency bands of the three-phase current signal are used as input, and the microgrid inverter fault diagnosis results are used as the output to establish a neural network structure, which can well diagnose microgrid inverter switch faults. With positioning, there is no need to set a threshold, which is more conducive to actual operation and has relatively high accuracy.

Description

technical field [0001] The invention belongs to the field of micro-grid fault diagnosis, in particular to a micro-grid inverter self-adaptive fault diagnosis method based on multi-band skewness analysis. Background technique [0002] With the continuous improvement of people's requirements for energy quality, micro-grid technology has attracted more and more attention. The reliability of the inverter is the basic guarantee for the normal operation of the microgrid. The failure of the inverter will affect the normal operation of many other components of the system, resulting in unstable power output and many adverse effects. Therefore, the fault diagnosis of the microgrid inverter system is of great significance in maintaining the normal operation of the system and reducing economic losses. [0003] Although there are a variety of related inverter fault diagnosis methods, there are still many deficiencies: most of the inverter fault diagnosis methods are aimed at the diagno...

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Problems solved by technology

[0003] Although there are a variety of related inverter fault diagnosis methods, there are still many deficiencies: most of the inverter fault diagnosis methods are aimed at the diagnosis of inverter open-circuit faults, mainly because it is difficult to realize short-circuit fault diagnosis and Classification

With the development of smart grid technology, the increasing types of new grids, the continuous expansion of scale, and the unpredictability of the demand side, it is difficult to accurately construct the mathematical model of the grid, and it is even more difficult to achieve fault diagnosis through precise mathematical methods. and recovery

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