Method for improving power grid low-voltage ride through capability based on wavelet detection

A low-voltage ride-through, power grid technology, applied in the direction of measuring electricity, measuring electrical variables, measuring devices, etc., can solve problems such as easy fluctuations, threats to the safe operation of power grids, and large drops.

Inactive Publication Date: 2018-09-21
HARBIN UNIV OF SCI & TECH
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Problems solved by technology

This kind of power grid is relatively weak and prone to fluctuations, which will affect the stable operation of the wind turbines, and even drop sharply. If the wind turbines are disconnected on a large scale at this time, it will pose a serious threat to the safe operation of the power grid.

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  • Method for improving power grid low-voltage ride through capability based on wavelet detection
  • Method for improving power grid low-voltage ride through capability based on wavelet detection
  • Method for improving power grid low-voltage ride through capability based on wavelet detection

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Embodiment Construction

[0020] The specific embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0021] A method based on wavelet detection to improve low-voltage ride-through capability of power grid, such as figure 1 shown, including the following steps:

[0022] Step 1. After the grid voltage drops, the current will suddenly increase, and a singular point will be generated. First, the singular point is detected by the detection device;

[0023] Step 2. Separate the fault signal and noise by wavelet noise reduction, so as to eliminate the interference of noise. In essence, it is necessary to eliminate the high-frequency signal represented by the noise on the premise of retaining the high-frequency signal represented by the fault information. Signal;

[0024] Step 3. Use wavelet decomposition to process the collected fault signals to obtain fault information. Wavelet theory is a variable-resolution analysis method based on ...

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Abstract

The present invention provides a method for improving power grid low-voltage ride through capability based on wavelet detection, belonging to the field of wind power generation. The method comprises the steps of: at a power grid voltage drop moment, allowing the current to be sharply increased, detecting and collecting signals to be detected; detecting singular points of the signals to be detectedthrough wavelet packet decomposition in the wavelet detection, extracting fault points, utilizing the wavelet noise reduction method to perform separation of the signals and the noise, and performingreconstruction; according to fault points generating short circuit, collecting short-circuit information of three-path signals; according to the short-circuit information, determining fault phases through calculation of a wavelet entropy algorithm and a wavelet entropy weight curve; setting safety thresholds of different split-phase switching fault current limiter input modes; and after fault phase selection is performed, detecting the depth of fault generation through the wavelet entropy so as to determine the drop degree of the fault voltages, comparing with the safety thresholds, and if the drop degree is larger than the safety thresholds, allowing the fault current limiter to be input in a corresponding mode. The power grid low-voltage ride through capability can be improved.

Description

technical field [0001] The invention relates to a method for improving the low-voltage ride-through capability of a power grid based on wavelet detection, which belongs to the field of wind power generation, and in particular to a method for improving the low-voltage ride-through capability of a power grid based on wavelet detection. Background technique [0002] Most wind farms are located in relatively remote areas, and most of the power grids connected to wind farms are far away from the load center. This kind of power grid is relatively weak and prone to fluctuations, which will affect the stable operation of the wind turbines and even drop sharply. If the wind turbines are disconnected on a large scale at this time, it will pose a serious threat to the safe operation of the power grid. As users have higher and higher requirements for the automation, intelligence and safe operation of the grid, how to quickly and accurately identify and diagnose the fault when the grid v...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08
CPCG01R31/086G01R31/088Y04S10/52
Inventor 吕艳玲徐春婷杨诗洁
Owner HARBIN UNIV OF SCI & TECH
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