Self-adaption fault diagnosis method of micro-grid inverter based on multi-frequency band skewness analysis

Abstract

A self-adaption fault diagnosis method of a micro-grid inverter based on multi-frequency band skewness analysis belongs to the field of micro power grid fault diagnosis. The self-adaption fault diagnosis method of the micro-grid inverter based on the multi-frequency band skewness analysis provided by the invention is based on changes of signal characteristics in different frequency bands before and after a fault, wherein a multi-resolution analysis method based on discrete wavelets extracts three-phase current decomposition coefficients in the different frequency bands and on multiple levels, acquires decomposition signals of a fault detection signal in the different frequency bands and on the multiple levels through reconstruction, and determines an optimal decomposition level number through energy analysis. After that, the skewness analysis is respectively carried out to the multi-level decomposition signals in the different frequency bands and thus obtains a skewness characteristic value of each decomposition signal to indicate a distortion degree of each decomposition signal caused by the fault. At last, the skewness characteristic value of each decomposition signal of a three-phase current signal in the different frequency bands is taken as the input, a fault diagnosis result of the micro-grid inverter is taken as the output and thus a neural network structure is established, so that diagnosis and positioning of the switch fault of the micro power grid inverter can be effectively realized, and no threshold value needs to be set. The method is more advantageous for actual operations and utilization and has relatively high precision.

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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