Grid-connected inverter island detection method based on wavelet transform and neural network

Abstract

The invention discloses a grid-connected inverter island detection method based on wavelet transform and a neural network. The method is characterized in that the method comprises the following steps: firstly, gathering voltage values of a distributed grid-connected power generation system at a point of common coupling at island state and non-island state and the output current value of an inverter, then performing wavelet transform on the gathered voltage values and the output current value of the inverter and exacting high-frequency component wavelet coefficients to be processed, and finally taking processed signals as input signals of the neural network, and taking corresponding island state and non-island stage as output signals to train the neural network, so as to ensure that the system obtains recognition capability to the island state and the non-island state, and to adopt corresponding island protection measures when the distributed grid-connected power generation system is at the island state. The method can not only overcome the disadvantages of the existing passive island detection method that the detection blind area is large and the detection time is long, but also can solve the problem that the active island detection method affects the power supply quality of the distributed grid-connected power generation system, and rapidly accomplish island detection and island protection.

Description

technical field [0001] The invention belongs to the technical field of island detection of a distributed grid-connected power generation system, in particular to a grid-connected inverter island detection method based on wavelet transform and neural network. Background technique [0002] With the intensification of the energy crisis and the enhancement of environmental protection awareness, distributed generation systems based on renewable energy such as solar energy and wind energy have attracted more and more attention. These renewable energy sources are usually converted into electrical energy and then delivered to the grid through grid-connected inverters. Islanding effect is a phenomenon that may occur in distributed grid-connected power generation systems. The so-called islanding phenomenon means that when the power grid is interrupted for some reason, the inverter still transmits power to the grid, forming a self-sufficient power supply island with the local load tha...

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Problems solved by technology

[0005] The object of the present invention is to address the deficiencies of the above-mentioned technologies, and provide a grid-connected inverter island detection method based on wavelet transform and neural network, which can overcome the shortcomings of the existing passive island detection method, such as large detection blind area and long detection time , and can solve the problem that the active island detection method affects the power supply quality of the distributed power generation system; on the premise of not affecting the power supply quality of the distributed power generation system, quickly complete the island detection and island protection to limit or even eliminate the blind area of ​​the island detection

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