A Point Detection Method of Voltage Sag Waveform Based on Space Vector Method

A space vector and voltage sag technology, applied in the field of electricity, can solve problems such as algorithm errors

Active Publication Date: 2019-08-20
SICHUAN UNIV
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  • Application Information

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Problems solved by technology

[0017] The purpose of the present invention is to solve the error defect existing in the principle of the existing algorithm, and propose a new voltage sag waveform point detection method based on the space vector method, which is based on the angle of the space vector in the complex plane relative to the real axis , which is more accurate than finding the nearest upward zero-crossing point and comparing it to calculate the waveform point

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  • A Point Detection Method of Voltage Sag Waveform Based on Space Vector Method
  • A Point Detection Method of Voltage Sag Waveform Based on Space Vector Method
  • A Point Detection Method of Voltage Sag Waveform Based on Space Vector Method

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Embodiment

[0099] The basic principle of the space vector method is to use the three-phase voltage to construct a space vector and express it in the complex plane. Then, the space vector characteristics are theoretically evaluated for the normal operation of the system and voltage sag.

[0100] The formula for constructing a space vector is as follows:

[0101]

[0102] Its essence is to rotate the voltage of phase b counterclockwise by 120° and the voltage of phase c counterclockwise by 240°, add it to the voltage of phase a and multiply it by a factor of 2 / 3 to construct a space vector x(t), which is multiplied by a factor of 2 / 3 is to save the magnitude between the two coordinate systems.

[0103] The radius of a space vector is defined as:

[0104]

[0105] From the definition of the space vector, it can be known that when the voltage is in a steady state, the radius of the space vector is basically unchanged, and the phase is the same as the phase a voltage, and the traject...

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Abstract

The present invention provides a voltage sag waveform point detection method based on the space vector method, which specifically includes the following steps: Step 1. Obtain the three-phase voltage instantaneous value waveform of the voltage sag to be detected. Step 2. Extract the basic features of known waveforms. Step 3. Construct a space vector through the three-phase voltage vector, and calculate the rate of change of the radius of the space vector. Step 4. Through the rate of change of the radius of the space vector, find the position of the sampling point where the waveform point is located. Step 5. Calculate the waveform point by combining the angle between the space vector x(t) and the real axis and the position of the sampling point obtained. The invention synthesizes space vectors by three-phase voltages, detects waveform points according to different characteristics of the space vectors when no sag occurs and when sag occurs, and solves errors in existing algorithms in principle.

Description

technical field [0001] The invention belongs to the field of electricity, and in particular relates to a method for finding a voltage sag waveform by using a space vector algorithm. Background technique [0002] Most power electronic devices in power systems are quite sensitive to dynamic power quality disturbances. Voltage sags can easily cause devices to fail to work normally, and the economic losses caused to users are often incalculable. As a product of the development of the times, power electronic equipment has been widely used in modern industrial production. Once these devices fail to work or stop working due to voltage sag, the entire production line will be affected, resulting in equipment shutdown, product scrapping, tool damage, and extension of the production period. Devices and industries will have an impact. [0003] In existing standards, the effective value (RMS) and duration of the voltage are considered as two basic characteristics of a voltage sag or sh...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R25/00
Inventor 汪颖邓凌峰肖先勇郑子萱
Owner SICHUAN UNIV
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